@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/107625,
    title ="Elemental Abundances of Major Elements in the Solar Wind as Measured in Genesis Targets and Implications on Solar Wind Fractionation",
    author = "Heber, Veronika S. and McKeegan, Kevin D.",
    journal = "Astrophysical Journal",
    volume = "907",
    number = "1",
    pages = "Art. No. 15",
    month = "January",
    year = "2021",
    doi = "10.3847/1538-4357/abc94a",
    issn = "1538-4357",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20210121-101410476",
    note = "© 2021. The American Astronomical Society. \n\nReceived 2020 September 8; revised 2020 October 27; accepted 2020 November 9; published 2021 January 20. \n\nWe appreciate the expertise and cooperation of the curatorial team at NASA Johnson Space Center in cleaning the Genesis collector fragments. D. Ledu, F. Fortuna (CSNSM Orsay), E. Briand, and J.-J. Ganem (Universités Pierre et Marie Curie and Namur) are thanked for standard implantations and nuclear reaction analyses. We appreciate discussions with P. Bochsler and comments and suggestions by the reviewer. The UCLA ion microprobe facility is partially supported by a grant from the NSF Instrumentation and Facilities program. V.S.H. thanks NASA for financial support. This work was supported by grants from the NASA Laboratory Analysis of Returned Samples (LARS) program (NASA LARS 80NSSC17K0025 to D.S.B. and A.J.G.J. R.W. acknowledges the hospitality of Caltech's Division of Geological and Planetary Sciences during his stay in Pasadena.",
    revision_no = "10",
    abstract = "We present elemental abundance data of C, N, O, Na, Mg, Al, Ca, and Cr in Genesis silicon targets. For Na, Mg, Al, and Ca, data from three different solar wind (SW) regimes are also presented. Data were obtained by backside depth profiling using secondary ion mass spectrometry. The accuracy of these measurements exceeds those obtained by in situ observations; therefore, the Genesis data provide new insights into elemental fractionation between Sun and SW, including differences between SW regimes. We integrate previously published noble gas and hydrogen elemental abundances from Genesis targets, as well as preliminary values for K and Fe. The abundances of the SW elements measured display the well-known fractionation pattern that correlates with each element's first-ionization potential (FIP). When normalized either to spectroscopic photospheric solar abundances or to those derived from CI-chondritic meteorites, the fractionation factors of low-FIP elements (K, Na, Al, Ca, Cr, Mg, Fe) are essentially identical within uncertainties, but the data are equally consistent with increasing fractionation with decreasing FIP. The elements with higher FIPs between ~11 and ~16 eV (C, N, O, H, Ar, Kr, Xe) display a relatively well-defined trend of increasing fractionation with decreasing FIP, if normalized to modern 3D photospheric model abundances. Among the three Genesis regimes, the fast SW displays the least elemental fractionation for almost all elements (including the noble gases) but differences are modest: for low-FIP elements, the precisely measured fast–slow SW variations are less than 3%.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/103775,
    title ="Electron Microprobe/SIMS Determinations of Al in Olivine: Applications to Solar Wind, Pallasites and Trace Element Measurements",
    author = "Paque, Julie M. and Hofmann, Amy E.",
    journal = "Geostandards and Geoanalytical Research",
    volume = "44",
    number = "3",
    pages = "473-484",
    month = "September",
    year = "2020",
    doi = "10.1111/ggr.12347",
    issn = "1639-4488",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20200608-133209595",
    note = "© 2020 The Authors. Geostandards and Geoanalytical Research © 2020 International Association of Geoanalysts. \n\nIssue Online: 12 August 2020; Version of Record online: 21 July 2020; Accepted manuscript online: 08 June 2020; Manuscript accepted: 26 May 2020; Manuscript received: 05 December 2019. \n\nFunding: National Aeronautics and Space Administration. Grant Number: 89NSSC17K0025.",
    revision_no = "15",
    abstract = "Electron probe microanalyser measurements of trace elements with high accuracy are challenging. Accurate Al measurements in olivine are required to calibrate SIMS implant reference materials for measurement of Al in the solar wind. We adopt a combined EPMA/SIMS approach that is useful for producing SIMS reference materials as well as for EPMA at the ~100 µg g⁻¹ level. Even for mounts not polished with alumina photoelectron spectroscopy shows high levels of Al surface contamination. In order to minimise electron beam current density, a rastered 50 × 100 µm electron beam was adequate and minimised sensitivity to small Al‐rich contaminants. Reproducible analyses of eleven SIMS cleaned spots on San Carlos olivine agreed at 69.3 ± 1.0 µg g⁻¹. The known Al mass fraction was used to calibrate an Al implant into San Carlos. Accurate measurements of Al were made for olivines in the pallasites: Imilac, Eagle Station and Springwater. Our focus was on Al in olivine; but our technique could be refined to give accurate electron probe measurements for other contamination‐sensitive trace elements. For solar wind it is projected that the Al/Mg abundance ratio can be determined to 6%, a factor of 2 more precise than the solar spectroscopic ratio.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/102042,
    title ="Refined composition of Solar Wind xenon delivered by Genesis NASA mission: Comparison with xenon captured by extraterrestrial regolith soils",
    author = "Meshik, Alex and Pravdivtseva, Olga",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "276",
    
    pages = "289-298",
    month = "May",
    year = "2020",
    doi = "10.1016/j.gca.2020.03.001",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20200323-093930814",
    note = "© 2020 Elsevier Ltd. \n\nReceived 19 November 2019, Accepted 2 March 2020, Available online 21 March 2020. \n\nWe are grateful to Judy Allton, Patti Burkett, Wally Calaway, Amy Jurewicz, Karen McNamara, Melissa Rodriguez (Genesis Science team), John Saxton and Phil Freedman (Nu Instruments, now Cameca) for their support. We thank Gregory Herzog, Bernard Marty, Rainer Wieler and an anonymous reviewer for their valuable comments and very helpful suggestions. This work is supported by NASA grant 80NSSC17K0018.",
    revision_no = "12",
    abstract = "The Genesis mission captured Solar Wind (SW) and delivered it to Earth for laboratory analyses. Due to advanced mass spectrometric techniques developed specifically for analyses of returned Genesis SW-collectors, SW-oxygen, nitrogen and noble gas isotopes have been successfully measured providing new insights for cosmo- and geochemistry. SW-Xe collected by Genesis is the heaviest and the least abundant SW element analyzed. Here we describe in detail the experimental improvements we made over last 5\u202fyears and a latest refined SW-Xe isotopic composition. Combined with earlier, already published SW-Xe analyses, our new results provide the best current estimate for SW-Xe collected by Genesis: ¹³⁶Xe/¹³⁰Xe\u202f=\u202f1.818\u202f±\u202f0.004; ¹³⁴Xe/¹³⁰Xe\u202f=\u202f2.242\u202f±\u202f0.005; ¹³²Xe/¹³⁰Xe\u202f=\u202f6.063\u202f±\u202f0.010; ¹³¹Xe/¹³⁰Xe\u202f=\u202f5.010\u202f±\u202f0.012; ¹²⁹Xe/¹³⁰Xe\u202f=\u202f6.314\u202f±\u202f0.013; ¹²⁸Xe/¹³⁰Xe\u202f=\u202f0.510\u202f±\u202f0.001; ¹²⁶Xe/¹³⁰Xe\u202f=\u202f0.0256\u202f±\u202f0.0004; ¹²⁴Xe/¹³⁰Xe\u202f=\u202f0.0292\u202f±\u202f0.0004 (all errors are 1σ). The achieved precision allows resolving small, but now statistically significant isotopic difference between solar wind Xe and Xe trapped in lunar regolith samples. This emerging difference, not apparent prior to this study, likely points to the composition of indigenous lunar Xe and to the temporal evolution of terrestrial Xe.\nCombining our Xe fluence with that for other high first ionization potential (FIP) elements, we find that the depletion of elements with the FIP greater than 12\u202feV is not constant but monotonically decreases as FIP increases.\n",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/100484,
    title ="Hydrogen fluence in Genesis collectors: Implications for acceleration of solar wind and for solar metallicity",
    author = "Huss, Gary R. and Koeman‐Shields, Elizabeth",
    journal = "Meteoritics and Planetary Science",
    volume = "55",
    number = "2",
    pages = "326-351",
    month = "February",
    year = "2020",
    doi = "10.1111/maps.13420",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20200103-091227050",
    note = "© 2019 The Meteoritical Society. \n\nReceived 05 November 2018; revision accepted 26 October 2019. \n\nWe thank the Genesis curatorial facility at JSC for working with us to get the right samples for this work. The paper benefited from a thoughtful review by Martin Laming. Supported by NASA grants NNX09AC32G, NNX14AF25G, and NNX17AE73G to G.R.H. and NNX09AC35G, NNX14AF26G, and 80NSSC17K0025 to D.S.B.",
    revision_no = "42",
    abstract = "NASA's Genesis mission was flown to capture samples of the solar wind and return them to the Earth for measurement. The purpose of the mission was to determine the chemical and isotopic composition of the Sun with significantly better precision than known before. Abundance data are now available for noble gases, magnesium, sodium, calcium, potassium, aluminum, chromium, iron, and other elements. Here, we report abundance data for hydrogen in four solar wind regimes collected by the Genesis mission (bulk solar wind, interstream low‐energy wind, coronal hole high‐energy wind, and coronal mass ejections). The mission was not designed to collect hydrogen, and in order to measure it, we had to overcome a variety of technical problems, as described herein. The relative hydrogen fluences among the four regimes should be accurate to better than ±5–6%, and the absolute fluences should be accurate to ±10%. We use the data to investigate elemental fractionations due to the first ionization potential during acceleration of the solar wind. We also use our data, combined with regime data for neon and argon, to estimate the solar neon and argon abundances, elements that cannot be measured spectroscopically in the solar photosphere.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/101158,
    title ="Magnesium isotopes of the bulk solar wind from Genesis diamond‐like carbon films",
    author = "Jurewicz, A. J. G. and Rieck, K. D.",
    journal = "Meteoritics and Planetary Science",
    volume = "55",
    number = "2",
    pages = "352-375",
    month = "February",
    year = "2020",
    doi = "10.1111/maps.13439",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20200206-112311510",
    note = "© 2020 The Authors. Meteoritics & Planetary Science published by Wiley Periodicals, Inc. on behalf of The Meteoritical Society (MET). This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. \n\nReceived 09 December 2018; revision accepted 10 December 2019. Version of Record online: 22 January 2020. \n\nSIMS analysis at Arizona State University National SIMS facility, was supported by EAR0622775. This work was initiated using Genesis Mission Funds, including JPL subcontract #1354958. Subsequent work was supported by NASA LARS Grants # NNX14AF26G and 80NSSC17K0025 (DSB, AJ); NNX17AE73G (GRH); NNH15AZ25I and NNH15AZ67I (RW); 80NSSC18K0740 (DBR), NNH16AC39I, NNH17AE96I, and NNH17AE60I (JML); as well as by basic research funds of the Chief of Naval Research (JML) and NASA Emerging Worlds award NNX15AH41G (MW). Thanks to J. Ziegler, USNA Annapolis for advice on SRIM, L. Williams for oversight using the ASU Cameca IMS 6f, Phil Janney for supporting M. Wadhwa in the Isotope Cosmochemistry and Geochronology Laboratory, and Stephen Romaniello for his discussions on Mg isotopes. Tom Friedmann provided significant insight into the material properties of the DLC made at Sandia National Laboratory. Bernard Marty and three anonymous reviewers made excellent suggestions that greatly improved the quality of this manuscript. Special thanks to associate editor Marc Caffee for his effort and patience.",
    revision_no = "26",
    abstract = "NASA's Genesis Mission returned solar wind (SW) to the Earth for analysis to derive the composition of the solar photosphere from solar material. SW analyses control the precision of the derived solar compositions, but their ultimate accuracy is limited by the theoretical or empirical models of fractionation due to SW formation. Mg isotopes are “ground truth” for these models since, except for CAIs, planetary materials have a uniform Mg isotopic composition (within ≤1‰) so any significant isotopic fractionation of SW Mg is primarily that of SW formation and subsequent acceleration through the corona. This study analyzed Mg isotopes in a bulk SW diamond‐like carbon (DLC) film on silicon collector returned by the Genesis Mission. A novel data reduction technique was required to account for variable ion yield and instrumental mass fractionation (IMF) in the DLC. The resulting SW Mg fractionation relative to the DSM‐3 laboratory standard was (−14.4‰, −30.2‰) ± (4.1‰, 5.5‰), where the uncertainty is 2ơ SE of the data combined with a 2.5‰ (total) error in the IMF determination. Two of the SW fractionation models considered generally agreed with our data. Their possible ramifications are discussed for O isotopes based on the CAI nebular composition of McKeegan et al. (2011).",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/97997,
    title ="Noble gas elemental abundances in three solar wind regimes as recorded by the Genesis mission",
    author = "Vogel, Nadia and Heber, Veronika S.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "263",
    
    pages = "182-194",
    month = "October",
    year = "2019",
    doi = "10.1016/j.gca.2019.08.007",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20190819-104728104",
    note = "© 2019 Elsevier Ltd. \n\nReceived 22 January 2019, Accepted 7 August 2019, Available online 16 August 2019. \n\nWe appreciate the great support of the Genesis curation team at the Johnson Space Center, Houston with sample selection and cleaning. Heinrich Baur, Henner Busemann and Rosmarie Neukomm are thanked for technical support and discussions, and we acknowledge the very helpful comments by AE Gregory Herzog and three reviewers. This work was supported by the Swiss National Science Foundation.\n",
    revision_no = "15",
    abstract = "We discuss elemental abundances of noble gases in targets exposed to the solar wind (SW) onboard the “Genesis” mission during the three different SW “regimes”: “Slow” (interstream, IS) wind, “Fast” (coronal hole, CH) wind and solar wind related to coronal mass ejections (CME). To this end we first present new Ar, Kr, and Xe elemental abundance data in Si targets sampling the different regimes. We also discuss He, Ne, and Ar elemental and isotopic abundances obtained on Genesis regime targets partly published previously. Average Kr/Ar ratios for all three regimes are identical to each other within their uncertainties of about 1% with one exception: the Fast SW has a 12% lower Xe/Ar ratio than do the other two regimes. In contrast, the He/Ar and Ne/Ar ratios in the CME targets are higher by more than 20% and 10%, respectively, than the corresponding Fast and Slow SW values, which among themselves vary by no more than 2–4%.\n\nEarlier observations on lunar samples and Genesis targets sampling bulk SW wind had shown that Xe, with a first ionisation potential (FIP) of ∼12\u202feV, is enriched by about a factor of two in the bulk solar wind over Ar and Kr compared to photospheric abundances, similar to many “low FIP” elements with a FIP less than ∼10\u202feV. This behaviour of the “high FIP” element Xe was not easily explained, also because it has a Coulomb drag factor suggesting a relatively inefficient feeding into the SW acceleration region and hence a depletion relative to other high FIP elements such as Kr and Ar. The about 12% lower enrichment of Xe in Genesis’ Fast SW regime observed here is, however, in line with the hypothesis that the depletion of Xe in the SW due to the Coulomb drag effect is overcompensated as a result of the relatively short ionisation time of Xe in the ion-neutral separation region in the solar chromosphere. We will also discuss the rather surprising fact that He and Ne in CME targets are quite substantially enriched (by 20% and 10%, respectively) relative to the other solar wind regimes, but that this enrichment is not accompanied by an isotopic fractionation. The Ne isotopic data in CMEs are consistent with a previous hypothesis that isotopic fractionation in the solar wind is mass-dependent.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/93224,
    title ="The future of Genesis science",
    author = "Burnett, D. S. and Jurewicz, A. J. G.",
    journal = "Meteoritics and Planetary Science",
    volume = "54",
    number = "5",
    pages = "1092-1114",
    month = "May",
    year = "2019",
    doi = "10.1111/maps.13266",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20190225-110316155",
    note = "© 2019 The Authors. Meteoritics & Planetary Science published by Wiley Periodicals, Inc. on behalf of The Meteoritical Society (MET). This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. \n\nVersion of Record online: 25 February 2019; Manuscript accepted: 30 January 2019; Manuscript received: 07 September 2016. \n\nWe benefitted from useful reviews from L. Nyquist, A. Davis, and M. Caffee. We also gratefully acknowledge two decades worth of assistance on Genesis at Caltech by Julie Paque and Janis Haskell. The work was supported by NASA LARS Grant 80NSSC17K0025.",
    revision_no = "20",
    abstract = "Solar abundances are important to planetary science since the prevalent model assumes that the composition of the solar photosphere is that of the solar nebula from which planetary materials formed. Thus, solar abundances are a baseline for planetary science. Previously, solar abundances have only been available through spectroscopy or by proxy (CI). The Genesis spacecraft collected and returned samples of the solar wind for laboratory analyses. Elemental and isotopic abundances in solar wind from Genesis samples have been successfully measured despite the crash of the re‐entry capsule. Here we present science rationales for a set of 12 important (and feasible postcrash) Science and Measurement Objectives as goals for the future (Table 1). We also review progress in Genesis sample analyses since the last major review (Burnett 2013). Considerable progress has been made toward understanding elemental fractionation during the extraction of the solar wind from the photosphere, a necessary step in determining true solar abundances from solar wind composition. The suitability of Genesis collectors for specific analyses is also assessed. Thus far, the prevalent model remains viable despite large isotopic variations in a number of volatile elements, but its validity and limitations can be further checked by several Objectives.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/83730,
    title ="Determining the Elemental and Isotopic Composition of the Pre-solar Nebula from Genesis Data Analysis: The Case of Oxygen",
    author = "Laming, J. Martin and Heber, V. S.",
    journal = "Astrophysical Journal Letters",
    volume = "851",
    number = "1",
    pages = "Art. No. L12",
    month = "December",
    year = "2017",
    doi = "10.3847/2041-8213/aa9bf0",
    issn = "2041-8213",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20171206-112123892",
    note = "© 2017 The American Astronomical Society.\n\nReceived 2017 August 29; revised 2017 October 30; accepted 2017 November 20; published 2017 December 6.\n\nThis work was supported by grants from the NASA Heliophysics Supporting Research (NNH16AC39I) and Laboratory Analysis of Returned Samples Programs (NNH17AE60I, NNH15AZ67I, NNX15AG19G) and by basic research funds of the Chief of Naval Research. We are grateful to Yuan-Kuen Ko for discussions of ACE data.",
    revision_no = "17",
    abstract = "We compare element and isotopic fractionations measured in bulk solar wind samples collected by NASA's Genesis mission with those predicted from models incorporating both the ponderomotive force in the chromosphere and conservation of the first adiabatic invariant in the low corona. Generally good agreement is found, suggesting that these factors are consistent with the process of solar wind fractionation. Based on bulk wind measurements, we also consider in more detail the isotopic and elemental abundances of O. We find mild support for an O abundance in the range 8.75–8.83, with a value as low as 8.69 disfavored. A stronger conclusion must await solar wind regime-specific measurements from the Genesis samples.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/78833,
    title ="Understanding heterogeneity in Genesis diamond-like carbon film using SIMS analysis of implants",
    author = "Jurewicz, Amy J. G. and Burnett, Don S.",
    journal = "Journal of Materials Science",
    volume = "52",
    number = "19",
    pages = "11282-11305",
    month = "October",
    year = "2017",
    doi = "10.1007/s10853-017-1267-3",
    issn = "0022-2461",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20170707-084238214",
    note = "© The Author(s) 2017. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. \n\nReceived: 28 January 2017. Accepted: 3 June 2017. First Online: 05 July 2017. \n\nSIMS analysis was supported by Arizona State University National SIMS facility, EAR0622775. Genesis mission funds include JPL sub-contract #1354958 and NASA LARS Grant #NNX14AF26G. We thank J. Ziegler, USNA Annapolis, for advice on SRIM, L. Williams for oversight using the ASU CAMECA IMS 6f, and Igor Veryovkin for his insight and helpful suggestions throughout all stages of this work. \n\nThere are no conflicts of interest which might bias or otherwise influence this work by the authors.",
    revision_no = "22",
    abstract = "An amorphous diamond-like carbon film deposited on silicon made at Sandia National Laboratory by pulsed laser deposition was one of several solar wind (SW) collectors used by the Genesis Mission (NASA Discovery Class Mission #5). The film was ~1 μm thick, amorphous, anhydrous, and had a high ratio of sp^3–sp^2 bonds (>50%). For 27 months of exposure to space at the first Lagrange point, the collectors were passively irradiated with SW (H fluence ~2 × 10^(16) ions cm^(−2); He fluence ~8 × 10^(14) ions cm^(−2)). The radiation damage caused by the implanted H ions peaked at 12–14 nm below the surface of the film and that of He about 20–23 nm. To enable quantitative measurement of the SW fluences by secondary ion mass spectroscopy, minor isotopes of Mg (^(25)Mg and ^(26)Mg) were commercially implanted into flight-spare collectors at 75 keV and a fluence of 1 × 10^(14) ions cm^(−2). The shapes of analytical depth profiles, the rate at which the profiles were sputtered by a given beam current, and the intensity of ion yields are used to characterize the structure of the material in small areas (~200 × 200 ± 50 μm). Data were consistent with the hypothesis that minor structural changes in the film were induced by SW exposure.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/78842,
    title ="Helium from Coronal Mass Ejecta Collected by NASA’s Genesis",
    author = "Yurimoto, H. and Tonotani, A.",
    journal = "Meteoritics and Planetary Science",
    volume = "52",
    number = "S1",
    pages = "401",
    month = "August",
    year = "2017",
    doi = "10.1111/maps.12934",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20170707-100238763",
    note = "© 2017 The Meteoritical Society. \n\nFirst published: 6 July 2017.",
    revision_no = "10",
    abstract = "The energy distribution of solar wind (SW) is an indicator of solar activity. The implantation profiles of SW particles in a solid material directly irradiated by the SW echo that energy distribution. Accordingly, the depth distribution of a SW element in a SW collector tells us about the solar activity during the time of collection. Helium is the second most abundant element of SW and almost free from terrestrial contamination, so it is one of the best candidates for measuring a detailed implantation profile. But, analysis of SW He by conventional depth-profiling methods have either extremely low He ionization yields or require extremely large sample volumes. Using the secondary neutral mass spectrometer, LIMAS, at Hokkaido University [1], we previously measured a SW He implantation profile from a bulk solar wind collector from the NASA Genesis SW sample return mission [2]. However, only the shape of the low-speed and high-speed SW He contributions were observed at that time, because the\nSW He component from coronal mass ejections (CMEs) was below our detection limit. Here we report our new, more sensitive measurements, which show CME flows collected by Genesis in the bulk solar wind collector.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/71307,
    title ="Discrimination and quantification of Fe and Ni abundances in Genesis solar wind implanted collectors using X-ray standing wave fluorescence yield depth profiling with internal referencing",
    author = "Choi, Y. and Eng, P.",
    journal = "Chemical Geology",
    volume = "441",
    
    pages = "246-255",
    month = "November",
    year = "2016",
    doi = "10.1016/j.chemgeo.2016.08.025",
    issn = "0009-2541",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20161020-075848529",
    note = "© 2016 Elsevier B.V. \n\nReceived 23 May 2016; Received in revised form 9 August 2016; Accepted 19 August 2016; Available online 21 August 2016. \n\nThe contributions of Kathy Kitts (the PI on the NASA grants supporting this project) are particularly acknowledged. Dr. Kitts was involved in identifying appropriate samples for this work, collecting XSW data and reporting the initial results. The curatorial staff at Johnson Space Center is thanked for providing the flown samples and the Genesis team for providing the implant standards. The manuscript was improved by the valuable reviews of A. Jurewicz and an anonymous reviewer. This research was supported by NASA Grants DDAP No. NNX07AG02G and SRLIDAP No. NNX07AL96G to Northern Illinois University (K. Kitts, PI), and NASA LARS grants NNX10AH05G to Loyola University Chicago (M. Schmeling, PI) and NNH09AM48I (I. Veryovkin, PI) to Argonne National Laboratory. This work was performed at GeoSoilEnviroCARS (The University of Chicago, Sector 13), Advanced Photon Source (APS), Argonne National Laboratory. GeoSoilEnviroCARS is supported by the National Science Foundation - Earth Sciences (EAR-1128799) and Department of Energy-GeoSciences (DE-FG02-94ER14466). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.",
    revision_no = "10",
    abstract = "X-ray standing wave fluorescence yield depth profiling was used to determine the solar wind implanted Fe and Ni fluences in a silicon-on-sapphire (SoS) Genesis collector (60326). An internal reference standardization method was developed based on fluorescence from Si and Al in the collector materials. Measured Fe fluence agreed well with that measured previously by us on a sapphire collector (50722) as well as SIMS results by Jurewicz et al. Measured Ni fluence was higher than expected by a factor of two; neither instrumental errors nor solar wind fractionation effects are considered significant perturbations to this value. Impurity Ni within the epitaxial Si layer, if present, could explain the high Ni fluences and therefore needs further investigation. As they stand, these results are consistent with minor temporally-variable Fe and Ni fractionation on the timescale of a year.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/61903,
    title ="Depth profiling analysis of solar wind helium collected in diamond-like carbon film from Genesis",
    author = "Bajo, Ken-ichi and Olinger, Chad T.",
    journal = "Geochemical Journal",
    volume = "49",
    number = "5",
    pages = "559-566",
    month = "September",
    year = "2015",
    doi = "10.2343/geochemj.2.0385",
    issn = "0016-7002",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20151105-124452080",
    note = "© 2015 by The Geochemical Society of Japan. \n\nReceived January 23, 2015; Accepted June 30, 2015. \n\nWe thank Hajime Hiyagon and an anonymous reviewer for their constructive reviews and suggestions and Yuji Sano for his kind editorial advice. This study is supported in part by Monka-sho grants. This is a contribution to Los Alamos publication LA-UR-15-21508.",
    revision_no = "12",
    abstract = "The distribution of solar-wind ions in Genesis mission collectors, as determined by depth profiling analysis, constrains the physics of ion-solid interactions involving the solar wind. Thus, they provide an experimental basis for revealing ancient solar activities represented by solar-wind implants in natural samples. We measured the first depth profile of ^4He in a Genesis collector; the shallow implantation (peaking at <20 nm) required us to use sputtered neutral mass spectrometry with post-photoionization by a strong field. The solar wind He fluence calculated using depth profiling is ~8.5 × 10^(14) cm^(–2). The shape of the solar wind 4He depth profile is consistent with TRIM simulations using the observed ^4He velocity distribution during the Genesis mission. It is therefore likely that all solar-wind elements heavier than H are completely intact in this Genesis collector and, consequently, the solar particle energy distributions for each element can be calculated from their depth profiles. Ancient solar activities and space weathering of solar system objects could be quantitatively reproduced by solar particle implantation profiles.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51554,
    title ="Ion Implants as Matrix-Appropriate Calibrators for Geochemical Ion Probe Analyses",
    author = "Burnett, Donald S. and Jurewicz, Amy J. G.",
    journal = "Geostandards and Geoanalytical Research",
    volume = "39",
    number = "3",
    pages = "265-276",
    month = "September",
    year = "2015",
    doi = "10.1111/j.1751-908X.2014.00318.x",
    issn = "1639-4488",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141111-093651164",
    note = "© 2014 The Authors. Geostandards and Geoanalytical Research © 2014 International Association of Geoanalysts. \n\nReceived 15 Apr 14; Accepted 09 Sep 14. Article first published online: 29 Jan 2015. \n\nThe authors thank two anonymous reviewers and the editors for helpful comments on the manuscript. Support for this work is greatly acknowledged from NASA LARS grants NNX14AF26G (Burnett), NNX13AD13G (McKeegan), NNX07AG19G (Nittler), NNX09AC62G (Humayun) and NNX13AD11G (Humayun); NASA Cosmochemistry grant NNX10AJ15G (Paque) and NSF EAR-0948878 (Hervig).",
    revision_no = "34",
    abstract = "Ion microprobe elemental and isotopic determinations can be precise but difficult to quantify. Error is introduced when the reference material and the sample to be analysed have different compositions. Mitigation of such “matrix effects” is possible using ion implants. If a compositionally homogeneous reference material is available which is “matrix-appropriate,” i.e., close in major element composition to the sample to be analysed, but having an unknown concentration of the element, E, to be determined, ion implantation can be used to introduce a known amount of an E isotope, calibrating the E concentration and producing a matrix-appropriate calibrator. Nominal implant fluences (ions cm^(−2)) are inaccurate by amounts up to approximately 30%. However, ion implantation gives uniform fluences over large areas, thus it is possible to “co-implant” an additional reference material of any bulk composition having known amounts of E, independently calibrating the implant fluence. Isotope-ratio measurement standards can be produced by implanting two different isotopes, but permil level precision requires post-implant calibration of the implant isotopic ratio. Examples discussed include: (1) standardising Li in melilite; (2) calibrating a ^(25)Mg implant fluence using NIST SRM 617 glass; and (3) using Si co-implanted with ^(25)Mg alongside NIST SRM 617 to produce a calibrated measurement of Mg in Si.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/59954,
    title ="Materials Older Than Ca-Al-Rich Inclusions",
    author = "Paque, J. M. and Burnett, D. S.",
    journal = "Meteoritics and Planetary Science",
    volume = "50",
    number = "S1",
    pages = "Art. No. 5281",
    month = "August",
    year = "2015",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150828-111222397",
    note = "© 2015 Meteoritical Society.",
    revision_no = "11",
    abstract = "Concentrations of refractory lithophile elements (RLEs) in Type B1 Ca-Al-rich inclusions (CAIs) are dominated by submicron inclusions, which are potentially relict grains older than the host CAI. These objects are so common, albeit tiny, that it is often very difficult to find a “pure” melilite.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/59971,
    title ="Primitive Terrestrial Xenon: A Relation to Refined Composition of Solar Wind",
    author = "Meshik, A. and Pravdivtseva, O.",
    journal = "Meteoritics and Planetary Science",
    volume = "50",
    number = "S1",
    pages = "Art. No. 5371",
    month = "August",
    year = "2015",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150828-155627545",
    note = "© 2015 Meteoritical Society.\n\nThis work is supported by NASA grants NNX13AD14G and NNX14A124G.",
    revision_no = "10",
    abstract = "To explain the isotopic structure of terrestrial Xe, a hypothetical U-Xe (unrelated to uranium) was mathematically constructed using multidimensional correlation diagrams of stepwise heating data of carbonaceous chondrites [1]. The composition of U-Xe was derived without any references to solar Xe. Nevertheless U-Xe turned out to be almost identical to Solar Wind (SW) except for two heaviest isotopes ^(136)Xe and ^(134)Xe, in which U-Xe was depleted. The mismatch in these two heaviest Xe isotopes was attributed to either the presence of nearly pure Xe-H (heavy branch of Xe-HL) in the Sun or to deficit of Xe-H in the carbonaceous chondrites from which U-Xe composition has been de-rived. There are two difficulties in this approach: U-Xe has never been reproducibly observed and Xe-H and Xe-L are apparently inseparable.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/53180,
    title ="Accurate analysis of shallowly implanted solar wind ions by SIMS backside depth profiling",
    author = "Heber, Veronika S. and McKeegan, Kevin D.",
    journal = "Chemical Geology",
    volume = "390",
    
    pages = "61-73",
    month = "December",
    year = "2014",
    doi = "10.1016/j.chemgeo.2014.10.003",
    issn = "0009-2541",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150105-115434812",
    note = "© 2014 Elsevier B.V. \n\nReceived 29 March 2014. Received in revised form 1 October 2014. Accepted 2 October 2014. Available online 13 October 2014. Editor: K. Mezger. \n\nWe appreciate the expertise and cooperation of the curatorial team at NASA Johnson Space Center in cleaning Genesis collector fragments prior to preparation for backside profiling. Detailed reviews by Andrew Davis and Ulrich Ott are gratefully acknowledged. This work was supported by grants from the NASA Laboratory Analysis of Returned Samples (LARS) program. V. Heber thanks the NASA for financial support and Rainer Wieler (ETH Zurich, Switzerland) for the discussion and correction of the paper and for allowing her towork for a part of this project as a Visiting Scientist in his laboratory. The UCLA  ion microprobe facility is partially supported by a grant from the NSF Instrumentation and Facilities program. The high accuracy implantations were performed in CSNSM Orsay with the help of D. Ledu and F. Fortuna and supported by the CNRS interdisciplinary program (Défi Instrumentation aux limites), the ANR grant 11-BS56-0026 and through CSNSM-UCLA collaboration PICS CNRS grant “MicMet-LA”. The nuclear reaction analysis was performed with the help of E. Briand and J-J Ganem under the Convention for SAFIR@ALTAÏS between The Université Pierre et Marie Curie and The University of Namur.",
    revision_no = "17",
    abstract = "A method to quantitatively determine the fluences of shallowly-implanted solar wind ions returned to Earth by the Genesis Discovery mission is described. Through backside depth-profiling, we recover nearly complete depth profiles of implanted solar wind for several nonvolatile elements, including Mg, Al, Ca, Cr, and, to a lesser extent, Na, in silicon targets that collected bulk solar wind and solar wind from specific velocity regimes. We also determine the fluences of the volatile elements C, N, and O in silicon targets that collected bulk solar wind. By the use of appropriately calibrated ion implanted standards, fluences as low as 2 × 10^(10) atoms cm^(−2) can be determined with precision and accuracy typically in the few percent range. Specific approaches to sample preparation, sputtering artifacts during depth profiling by secondary ion mass spectrometry, and quantification including the production of ion implant standards are discussed.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/43977,
    title ="Heavy noble gases in solar wind delivered by Genesis mission",
    author = "Meshik, Alex and Hohenberg, Charles",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "127",
    
    pages = "326-347",
    month = "February",
    year = "2014",
    doi = "10.1016/j.gca.2013.11.030",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20140225-102334485",
    note = "© 2013 Elsevier Ltd. \n\nReceived 11 April 2013; accepted in revised form 23 November 2013; available online 7 December 2013. \n\nAssociate editor: Gregory F. Herzog. \n\nWe are grateful to Judy Allton, Patti Burkett, Wally Calaway, Amy Jurewicz, Karen McNamara,Melissa Rodriguez (Genesis Science team) and John Saxton and Phil Freedman (Nu Instruments) for their support. We thank Gregory Herzog, Kurt Marti, Robert Pepin and Jamie Gilmour for their valuable comments. This work is funded by NASA Grants NNX09AC57G and NNX13AD14G.",
    revision_no = "16",
    abstract = "One of the major goals of the Genesis Mission was to refine our knowledge of the isotopic composition of the heavy noble gases in solar wind and, by inference, the Sun, which represents the initial composition of the solar system. This has now been achieved with permil precision: ^(36)Ar/^(38)Ar = 5.5005 ± 0.0040, ^(86)Kr/^(84)Kr = .3012 ± .0004, ^(83)Kr/^(84)Kr = .2034 ± .0002, ^(82)Kr/^(84)Kr = .2054 ± .0002, ^(80)Kr/^(84)Kr = .0412 ± .0002, ^(78)Kr/^(84)Kr = .00642 ± .00005, ^(136)Xe/^(132)Xe = .3001 ± .0006, ^(134)Xe/^(132)Xe = .3691 ± .0007, ^(131)Xe/^(132)Xe = .8256 ± .0012, ^(130)Xe/^(132)Xe = .1650 ± .0004, ^(129)Xe/^(132)Xe = 1.0405 ± .0010, ^(128)Xe/^(132)Xe = .0842 ± .0003, ^(126)Xe/^(132)Xe = .00416 ± .00009, and ^(124)Xe/^(132)Xe = .00491 ± .00007 (error-weighted averages of all published data). The Kr and Xe ratios measured in the Genesis solar wind collectors generally agree with the less precise values obtained from lunar soils and breccias, which have accumulated solar wind over hundreds of millions of years, suggesting little if any temporal variability of the isotopic composition of solar wind krypton and xenon. The higher precision for the initial composition of the heavy noble gases in the solar system allows (1) to confirm that, exept ^(136)Xe and ^(134)Xe, the mathematically derived U–Xe is equivalent to Solar Wind Xe and (2) to provide an opportunity for better understanding the relationship between the starting composition and Xe-Q (and Q-Kr), the dominant current “planetary” component, and its host, the mysterious phase-Q.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/43484,
    title ="The Genesis solar wind sample return mission: Past, present, and future",
    author = "Burnett, D. S.",
    journal = "Meteoritics and Planetary Science",
    volume = "48",
    number = "12",
    pages = "2351-2370",
    month = "December",
    year = "2013",
    doi = "10.1111/maps.12241 ",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20140123-094533962",
    note = "© 2013 The Meteoritical Society.\n\nReceived 26 February 2013; revision accepted 10 April 2013.\n\nArticle first published online: 6 Dec. 2013.\nThis review is an expansion of the\n2012 Leonard Medal address. The success of Genesis\nwas a team effort, involving the work of hundreds of\nindividuals. Management, payload design, and mission\noperations were carried out at the Jet Propulsion\nLaboratory (JPL). Spacecraft and recovery were carried\nout by Lockheed Martin Astronautics (Denver).\nPayload integration and postcrash recovery was\nsmoothly executed by a JPL-JSC partnership.\nContingency planning by the JSC Genesis Curatorial\nstaff made possible the rapid postcrash recovery.\nA 2011 tabulation of scientists who worked on\nthe planning, implementation, recovery, and analysis phases of the Genesis Discovery mission is available\nat www.pnas.org/content/suppl/2011/05/06/1014877108.\nDCSupplemental. I have benefitted from discussions as\npart of the Solar Wind Composition Working Group\nsponsored by the International Space Sciences Institute\n(ISSI, Bern). Important advice on this manuscript from\nAmy Jurewicz, Alex Meshik, Charles Hohenberg, Roger\nWiens, and Julie Paque is gratefully acknowledged.\nHelpful reviews were obtained from A. Davis and an\nanonymous reviewer. This work was sponsored by\nNASA LARS grant: NNX09AC35G.",
    revision_no = "9",
    abstract = "The Genesis Discovery mission returned solar matter in the form of the solar wind with the goal of obtaining precise solar isotopic abundances (for the first time) and greatly improved elemental abundances. Measurements of the light noble gases in regime samples demonstrate that isotopes are fractionated in the solar wind relative to the solar photosphere. Theory is required for correction. Measurement of the solar wind O and N isotopes shows that these are very different from any inner solar system materials. The solar O isotopic composition is consistent with photochemical self-shielding. For unknown reasons, the solar N isotopic composition is much lighter than essentially all other known solar system materials, except the atmosphere of Jupiter. Ne depth profiling on Genesis materials has demonstrated that Ne isotopic variations in lunar samples are due to isotopic fractionation during implantation without appealing to higher energy solar particles. Genesis provides a precise measurement of the isotopic differences of Ar between the solar wind and the terrestrial atmosphere. The Genesis isotopic compositions of Kr and Xe agree with data from lunar ilmenite separates, showing that lunar processes have not affected the ilmenite data and that solar wind composition has not changed on 100 Ma time scales. Relative to Genesis solar wind, ArKrXe in Q (the chondrite noble gas carrier) and the terrestrial atmosphere show relatively large light isotope depletions.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/43366,
    title ="XANES and Mg isotopic analyses of spinels in Ca-Al-rich inclusions: Evidence for formation under oxidizing conditions",
    author = "Paque, J. M. and Sutton, S. R.",
    journal = "Meteoritics and Planetary Science",
    volume = "48",
    number = "10",
    pages = "2015-2043",
    month = "October",
    year = "2013",
    doi = "10.1111/maps.12216",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20140114-141328012",
    note = "© 2013 The Meteoritical Society. Received 11 March 2013; revision accepted 12 September 2013. \n\nArticle first published online: 24 Oct. 2013.\nThis work was supported by NASA grants NNX09AC35G (D. S. Burnett, PI); NNX09AG40G (E. Stolper, PI); NNX08AE06G (L. Grossman, PI) and by a Monka-sho grant (H. Yurimoto, PI). We thank Jérôme Aléon and an\nanonymous reviewer for their constructive comments.\nEditorial Handling—Dr. Christine Floss",
    revision_no = "14",
    abstract = "Ti valence measurements in MgAl_2O_4 spinel from calcium-aluminum-rich inclusions (CAIs) by X-ray absorption near-edge structure (XANES) spectroscopy show that many spinels have predominantly tetravalent Ti, regardless of host phases. The average spinel in Allende type B1 inclusion TS34 has 87% Ti^(+4). Most spinels in fluffy type A (FTA) inclusions also have high Ti valence. In contrast, the rims of some spinels in TS34 and spinel grain cores in two Vigarano type B inclusions have larger amounts of trivalent titanium. Spinels from TS34 have approximately equal amounts of divalent and trivalent vanadium. Based on experiments conducted on CAI-like compositions over a range of redox conditions, both clinopyroxene and spinel should be Ti^(+3)-rich if they equilibrated with CAI liquids under near-solar oxygen fugacities. In igneous inclusions, the seeming paradox of high-valence spinels coexisting with low-valence clinopyroxene can be explained either by transient oxidizing conditions accompanying low-pressure evaporation or by equilibration of spinel with relict Ti^(+4)-rich phases (e.g., perovskite) prior to or during melting. Ion probe analyses of large spinel grains in TS34 show that they are enriched in heavy Mg, with an average Δ^(25)Mg of 4.25 ± 0.028‰, consistent with formation of the spinel from an evaporating liquid. Δ^(25)Mg shows small, but significant, variation, both within individual spinels and between spinel and adjacent melilite hosts. The Δ^(25)Mg data are most simply explained by the low-pressure evaporation model, but this model has difficulty explaining the high Ti^(+4) concentrations in spinel.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/42876,
    title ="Solar Wind Krypton in Genesis Collectors and in Lunar Regolith:  Why are they Different?",
    author = "Meshik, A. and Hohenberg, C.",
    journal = "Meteoritics and Planetary Science",
    volume = "48",
    number = "S1",
    pages = "A243",
    month = "July",
    year = "2013",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20131206-090849117",
    note = "© 2013 The Meteoritical Society.\n\nArticle first published online: 1 Jul. 2013.\n\nThis work supported by NASA grants NNX09AC57G and\nNNHZDA001N.",
    revision_no = "11",
    abstract = "Compared to Xe, Kr demonstrates the smallest isotopic\nvariations among solar system components. At the same time Kr\nis more sensitive to terrestrial contamination since atmospheric\n^(84)Kr/^(132)Xe = 27.7 is the highest among all known solar and presolar\ncomponents. Therefore higher precision isotopic analyses,\nand careful control of contamination, are needed to make\naccurate determinations of Kr isotopic compositions of various\nsolar system components.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56903,
    title ="The Genesis SolarWind Concentrator: Flight and Post-Flight Conditions and Modeling of Instrumental Fractionation",
    author = "Wiens, Roger C. and Reisenfeld, Daniel B.",
    journal = "Space Science Reviews",
    volume = "175",
    number = "1-4",
    pages = "93-124",
    month = "June",
    year = "2013",
    doi = "10.1007/s11214-013-9961-1",
    issn = "0038-6308",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150423-092914490",
    note = "© 2013 Springer Science+Business Media Dordrecht.\n\nReceived: 8 August 2012; Accepted: 22 January 2013; Published online: 19 February 2013.\n\nThe authors at LANL are grateful for a grant from NASA’s Laboratory Analysis of Returned Samples (LARS) program, as well as Discovery Program office funding to the Genesis mission. The authors are also grateful to all who made possible the Concentrator experiment, including the Genesis flight. We thank the ACE SWICS instrument team and the ACE Science Center for providing the ACE data.",
    revision_no = "14",
    abstract = "The Genesis mission Solar Wind Concentrator was built to enhance fluences of solar wind by an average of 20x over the 2.3 years that the mission exposed substrates to the solar wind. The Concentrator targets survived the hard landing upon return to Earth and were used to determine the isotopic composition of solar-wind—and hence solar—oxygen and nitrogen. Here we report on the flight operation of the instrument and on simulations of its performance. Concentration and fractionation patterns obtained from simulations are given for He, Li, N, O, Ne, Mg, Si, S, and Ar in SiC targets, and are compared with measured concentrations and isotope ratios for the noble gases. Carbon is also modeled for a Si target. Predicted differences in instrumental fractionation between elements are discussed. Additionally, as the Concentrator was designed only for ions ≤22 AMU, implications of analyzing elements as heavy as argon are discussed. Post-flight simulations of instrumental fractionation as a function of radial position on the targets incorporate solar-wind velocity and angular distributions measured in flight, and predict fractionation patterns for various elements and isotopes of interest. A tighter angular distribution, mostly due to better spacecraft spin stability than assumed in pre-flight modeling, results in a steeper isotopic fractionation gradient between the center and the perimeter of the targets. Using the distribution of solar-wind velocities encountered during flight, which are higher than those used in pre-flight modeling, results in elemental abundance patterns slightly less peaked at the center. Mean fractionations trend with atomic mass, with differences relative to the measured isotopes of neon of +4.1±0.9 ‰/amu for Li, between −0.4 and +2.8 ‰/amu for C, +1.9±0.7‰/amu for N, +1.3±0.4 ‰/amu for O, −7.5±0.4 ‰/amu for Mg, −8.9±0.6 ‰/amu for Si, and −22.0±0.7 ‰/amu for S (uncertainties reflect Monte Carlo statistics). The slopes of the fractionation trends depend to first order only on the relative differential mass ratio, Δm/m.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/35462,
    title ="The isotopic composition and fluence of solar-wind nitrogen in a genesis B/C array collector",
    author = "Huss, Gary R. and Nagashima, Kazuhide",
    journal = "Meteoritics and Planetary Science",
    volume = "47",
    number = "9",
    pages = "1436-1448",
    month = "September",
    year = "2012",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20121114-120747648",
    note = "© 2012 Meteoritical Society. Received 06 April 2011; revision accepted 22 July 2012. \n\nArticle first published online: 14 Sep. 2012.\nEditorial Handling—Dr. Ian Franchi. This paper benefited from helpful reviews by Veronika Heber, Andrew Davis, and Bernard Marty. It was supported by NASA grant NNX09AC32G to GRH and NNX09AC35G to DSB. This is Hawai’i Institute of Geophysics and Planetology publication No. 1977 and School of Ocean and Earth Science and Technology publication No. 8696. Los Alamos National Laboratory publication LA-UR-12-24206. ",
    revision_no = "14",
    abstract = "We have measured the isotopic composition and fluence of solar-wind nitrogen in a diamond-like-carbon collector from the Genesis B/C array. The B and C collector arrays on the Genesis spacecraft passively collected bulk solar wind for the entire collection period, and there is no need to correct data for instrumental fractionation during collection, unlike data from the Genesis “Concentrator.” This work validates isotopic measurements from the concentrator by Marty et al. (2010, 2011); nitrogen in the solar wind is depleted in ^(15)N relative to nitrogen in the Earth’s atmosphere. Specifically, our array data yield values for ^(15)N/^(14)N of (2.17 ± 0.37) × 10^(−3) and (2.12 ± 0.34) × 10^(−3), depending on data-reduction technique. This result contradicts preliminary results reported for previous measurements on B/C array materials by Pepin et al. (2009), so the discrepancy between Marty et al. (2010, 2011) and Pepin et al. (2009) was not due to fractionation of solar wind by the concentrator. Our measured value of ^(15)N/^(14)N in the solar wind shows that the Sun, and by extension the solar nebula, lie at the low-^(15)N/^(14)N end of the range of nitrogen isotopic compositions observed in the solar system. A global process (or combination of processes) must have operated in interstellar space and/or during the earliest stages of solar system formation to increase the ^(15)N/^(14)N ratio of the solar system solids. We also report a preliminary Genesis solar-wind nitrogen fluence of (2.57 ± 0.42) × 10^(12) cm^(−2). This value is higher than that derived by backside profiling of a Genesis silicon collector (Heber et al. 2011a).",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/34645,
    title ="Evidence for Unfractionated Magnesium Isotopes in Genesis SOS Wafers",
    author = "Humayun, M. and Jurewicz, A. J. G.",
    journal = "Meteoritics and Planetary Science",
    volume = "47",
    number = "S1",
    pages = "A202-A202",
    month = "July",
    year = "2012",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20121002-155323510",
    note = "© 2012 Meteoritical Society. Issue published online: 6 Aug 2012. Article first published online: 8 Aug 2012.",
    revision_no = "11",
    abstract = "Oxygen isotopes measured by MegaSIMS on\nGenesis Concentrator samples indicate a solar wind (SW) oxygen isotope composition that is related to the ^(16)O-enriched CAI composition by a large mass dependent fractionation [I]. Isotope fractionation during acceleration of the solar wind is expected to create\nsuch a large mass fractionation, but a direct test of the presence of mass fractionation in the solar wind has not been possible with sufficient precision. Unlike O and Ne, Mg isotopes are sufficiently uniform in chondrites, terrestrial samples, and other meteoritic and planetary materials from the inner solar system [2], and so offer the best opportunity for a precise (±1‰) test of the Coulomb Drag mechanism for solar wind isotope fractionation.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/34646,
    title ="Genesis Solar Composition: Past, Present, and Future",
    author = "Burnett, D. S.",
    journal = "Meteoritics and Planetary Science",
    volume = "47",
    number = "S1",
    pages = "A89-A89",
    month = "July",
    year = "2012",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20121002-155455985",
    note = "© 2012 Meteoritical Society. Issue published online: 6 Aug 2012. Article first published online: 8 Aug 2012.",
    revision_no = "11",
    abstract = "The Genesis Discovery Mission returned samples of\nsolar matter by exposing ultrapure materials to the solar wind for 27 months in 2002-04. The science objectives are: (I) measure solar isotopic abundances to planetary science precsion requirements. (II) improve knowledge of solar elemental abundances. (III) independently sample the 3 solar wind regimes. Except for the earth return crash, the mission was nominal. We recovered sufficient pieces to make analyses.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/32894,
    title ="Steps toward accurate large-area analyses of Genesis solar wind samples: evaluation of surface cleaning methods using total reflection X-ray fluorescence spectrometry",
    author = "Schmeling, Martina and Burnett, Donald S.",
    journal = "Powder Diffraction",
    volume = "27",
    number = "2",
    pages = "75-78",
    month = "June",
    year = "2012",
    
    issn = "0885-7156",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20120802-145043285",
    note = "© 2012 JCPDS-ICDD.\n\nReceived 1 March 2012; accepted 10 March 2012.\n\n\nThis work was supported by NASA/JPL grant 1369203\nand NASA grant NNX10AH05G. The work of I.V.V was\nsupported by NASA through grant NNH09AM48I, and by\nUChicago Argonne, LLC, under contract No.\nDE-AC02-06CH11 357. We thank C. E. Tripa for his help in\npreparing the CO_2 snow cleaned samples.\n",
    revision_no = "12",
    abstract = "Total reflection X-ray fluorescence spectrometry (TXRF) was used to analyze residual surface contamination on Genesis solar wind samples and to evaluate different cleaning methods. To gauge the suitability of a cleaning method, two samples were analyzed following cleaning by lab-based TXRF. The analysis comprised an overview and a crude manual mapping of the samples by orienting them with respect to the incident X-ray beam in such a way that different regions were covered. The results show that cleaning with concentrated hydrochloric acid and a combination of hydrochloric acid and hydrofluoric acid decreased persistent inorganic contaminants substantially on one sample. The application of CO2 snow for surface cleaning tested on the other sample appears to be effective in removing one persistent Genesis contaminant, namely germanium. Unfortunately, the TXRF analysis results of the second sample were impacted by relatively high background contamination. This was mostly due to the relatively small sample size and that the solar wind collector was already mounted with silver glue for resonance ion mass spectrometry (RIMS) on an aluminium stub. Further studies are planned to eliminate this problem. In an effort to identify the location of very persistent contaminants, selected samples were also subjected to environmental scanning electron microscopy. The results showed excellent agreement with TXRF analysis.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/28511,
    title ="Solar composition from the Genesis Discovery Mission\n",
    author = "Burnett, D. S.",
    journal = "Proceedings of the National Academy of Sciences of the United States of America",
    volume = "108",
    number = "48",
    pages = "19147-19151",
    month = "November",
    year = "2011",
    doi = "10.1073/pnas.1014877108   ",
    issn = "0027-8424",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20111219-093356766",
    note = "© 2011 by the National Academy of Sciences. Edited by Mark H. Thiemens, University of California, La Jolla, CA, and approved March 18, 2011 (received for review October 8, 2010). Published online before print May 9, 2011. I gratefully acknowledge the work of over 100 scientists\nrepresenting the Genesis Science Team, whose work has been summarized. A spacecraft mission is only possible with the contributions of hundreds of people. The Genesis Mission was executed by the Jet Propulsion Lab\n(management, payload design and fabrication, mission operations),\nLockheed Martin Astronautics (spacecraft, spacecraft operations), Los Alamos\nNational Lab (concentrator, regime monitors), NASA Johnson Space Center\n(payload integration), and the Mid-Continent Educational Lab (education\nand public outreach). Besides the Discovery Program, the Genesis Science\nTeam acknowledges support from the NASA Sample Return Laboratory Instrument\nDefinition Program (SRLIDAP) and Laboratory Analysis of Returned\nSamples (LARS) programs.\n\nAuthor contributions: D.S.B. and G.S.T. designed research; D.S.B. and G.S.T. performed\nresearch; G.S.T. contributed new reagents/analytic tools; D.S.B. and G.S.T. analyzed data;\nand D.S.B. and G.S.T. wrote the paper.",
    revision_no = "17",
    abstract = "Science results from the Genesis Mission illustrate the major advantages of sample return missions. (i) Important results not otherwise obtainable except by analysis in terrestrial laboratories: the isotopic compositions of O, N, and noble gases differ in the Sun from other inner solar system objects. The N isotopic composition is the same as that of Jupiter. Genesis has resolved discrepancies in the noble gas data from solar wind implanted in lunar soils. (ii) The most advanced analytical instruments have been applied to Genesis samples, including some developed specifically for the mission. (iii) The N isotope result has been replicated with four different instruments. ",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36631,
    title ="Feasibility of Iodine and Bromine Analysis in Genesis Solar Wind Collectors",
    author = "Pravdivtseva, O. and Meshik, A.",
    journal = "Meteoritics and Planetary Science",
    volume = "46",
    number = "S1",
    pages = "A192-A192",
    month = "July",
    year = "2011",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130128-142650955",
    note = "© 2011 The Meteoritical Society.\nArticle first published online: 25 Jul. 2011.\nThis work is supported by NASA grant NNX07AM76G.",
    revision_no = "8",
    abstract = "Comparison of elemental abundances in sun, meteorites and earth\nprovides understanding of the formation and evolution of the solar\nsystem. Yet, the majority of the solar system abundances are based on\nmeteoritic values [1–6]. Here we report an attempt to estimate a feasibility\nof direct measurements of iodine and bromine in the GENESIS solar\nwind Aluminum on Sapphire collector (AloS) using neutron induced\nconversions: ^(127)I(n,γβ)^(128)Xe, ^(79)Br(n,γβ)^(80)Kr and ^(81)Br(n,γβ)^(82)Kr.\n",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36629,
    title ="First Analysis of All Xenon Isotopes in Genesis Solar Wind AloS Collector",
    author = "Meshik, A. and Pravdivtseva, O.",
    journal = "Meteoritics and Planetary Science",
    volume = "46",
    number = "S1",
    pages = "A159-A159",
    month = "July",
    year = "2011",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130128-141043907",
    note = "© 2011 The Meteoritical Society.\nArticle first published online: 25 Jul. 2011.\nSupported by NASA grant NNX07AM76G.",
    revision_no = "9",
    abstract = "Recently we made successful measurements of all solar\nwind (SW) krypton isotopes in Genesis Al-collectors [1]. Here we report\nresults of 20 independent analysis of Xe extracted from Aluminum on\nSapphire (AloS) under four different experimental conditions.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36624,
    title ="Mg Isotopic Composition of the Solar Wind by SIMS Analysis of Genesis Targets",
    author = "Heber, V. S. and Jurewicz, A. J. G.",
    journal = "Meteoritics and Planetary Science",
    volume = "46",
    number = "S1",
    pages = "A90-A90",
    month = "July",
    year = "2011",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130128-111118039",
    note = "© 2011 The Meteoritical Society.\nArticle first published online: 25 Jul. 2011.\n\n",
    revision_no = "12",
    abstract = "In order to deduce the isotopic compositions in the\nsolar nebula of volatile elements, e.g., noble gases, O, and N, from analyses\nof the solar wind (SW), we must understand the magnitude of mass-dependent\nfractionation between the SW and the photosphere. With the\nexception of evaporation effects in CAIs, mass-dependent fractionation of\nMg isotopes is small, as evidenced by Mg isotopic compositions of\nterrestrial igneous and meteoritic samples which agree within ~1‰ [1].\nThus, if we assume that the \"terrestrial\" Mg isotopic composition is also\nrepresentative of the solar photosphere, we can use measurements of the\nSW captured by Genesis to test models of isotopic fractionation in\nformation of SW. For example, if the inefficient Coulomb-drag model [2]\nis correct, we would expect that the Mg isotopic composition in the SW is\n~10‰ per amu [2] lighter than the terrestrial composition.\n",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/24360,
    title ="A ^(15)N-Poor Isotopic Composition for the Solar System As Shown by Genesis Solar Wind Samples",
    author = "Marty, B. and Chaussidon, M.",
    journal = "Science",
    volume = "332",
    number = "6037",
    pages = "1533-1536",
    month = "June",
    year = "2011",
    
    issn = "0036-8075",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20110711-113456583",
    note = "© 2011 American Association for the Advancement of Science. \n\nReceived 22 February 2011; accepted 26 April 2011.\n\nFunding in the U.S. was provided by NASA through the Genesis Discovery Mission and through the Laboratory Analysis of Returned Samples program. The ultimate success of the mission would not have been possible without major engineering contributions from the Los Alamos National Laboratory (Genesis Concentrator), Jet Propulsion Laboratory (payload, mission operations, management), Lockheed Martin Aerospace (spacecraft and reentry capsule), and the Johnson Space Center (payload integration and curation). This study was funded in France by the Centre National d’Etudes Spatiales, the Centre National de la Recherche Scientifique, the French Ministery of Higher Education and Research, the Région Lorraine, the Fonds Européen de Développement Régional, and the European Research Council under the European Community’s\nSeventh Framework Programme (FP7/2007-2013 grant\nagreements no. 226846 to M.C. and no. 267255 to B.M.).\nWe particularly thank J. D. Allton for excellent sample\ncuration and C. Olinger for ion trajectory calculations.\nThe SiC standard was provided by A. Kallio. This work\nbenefitted from discussions with the members of the\nGenesis Science Team, in particular, R. O. Pepin, R. Wieler,\nand A. N. Davies. Comments on the draft by V. S. Heber,\nK. McKeegan, P. Bochsler, and three reviewers were\nappreciated. The full data set is available as supporting\nonline material (SOM).",
    revision_no = "27",
    abstract = "The Genesis mission sampled solar wind ions to document the elemental and isotopic compositions of the Sun and, by inference, of the protosolar nebula. Nitrogen was a key target element because the extent and origin of its isotopic variations in solar system materials remain unknown. Isotopic analysis of a Genesis Solar Wind Concentrator target material shows that implanted solar wind nitrogen has a ^(15)N/^(14)N ratio of 2.18 ± 0.02 × 10^(−3) (that is, ≈40% poorer in ^(15)N relative to terrestrial atmosphere). The ^(15)N/^(14)N ratio of the protosolar nebula was 2.27 ± 0.03 × 10^(−3), which is the lowest ^(15)N/^(14)N ratio known for solar system objects. This result demonstrates the extreme nitrogen isotopic heterogeneity of the nascent solar system and accounts for the ^(15)N-depleted components observed in solar system reservoirs. ",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/24371,
    title ="The Oxygen Isotopic Composition of the Sun Inferred from Captured Solar Wind",
    author = "McKeegan, K. D. and Kallio, A. P. A.",
    journal = "Science",
    volume = "332",
    number = "6037",
    pages = "1528-1532",
    month = "June",
    year = "2011",
    
    issn = "0036-8075",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20110712-092913351",
    note = "© 2011 American Association for the Advancement of Science.\n\nReceived for publication 21 February 2011; accepted for publication 10 May 2011.\n\nWe gratefully acknowledge financial support from the NASA programs Discovery, SRLIDAP/LARS, and Cosmochemistry. The ultimate success of the Genesis Discovery Mission would not have been possible without major engineering contributions from the Los Alamos National Laboratory (Concentrator),\nJet Propulsion Laboratory (payload, mission operations, management), Lockheed Martin Aerospace (spacecraft and re-entry capsule), and the Johnson Space Center\n(payload integration and curation). The MegaSIMS laboratory received financial support from UCLA and NASA as well as important technical support from the National Electrostatics Corporation, Kore Technology Ltd, CAMECA, and R. Plue. We benefited from expert advice from J. Huneke, C. Evans Jr., M. Suter, H. Synal, K. Grabowski, S. Smith, and P. Williams. We appreciate collaborations with the accelerator team at Orsay, led by J. Duprat and G. Slodzian. The sample investigated here was well cared for by J. Allton, E. Stansbery, and their Johnson Space Center team. We are grateful for help and advice from A. Davis, D. Papanastassiou, N. Vogel, R. Wieler, D. Woolum, the reviewers of this manuscript, and the entire Genesis Science Team.\n",
    revision_no = "20",
    abstract = "All planetary materials sampled thus far vary in their relative abundance of the major isotope of oxygen, ^(16)O, such that it has not been possible to define a primordial solar system composition. We measured the oxygen isotopic composition of solar wind captured and returned to Earth by NASA’s Genesis mission. Our results demonstrate that the Sun is highly enriched in ^(16)O relative to the Earth, Moon, Mars, and bulk meteorites. Because the solar photosphere preserves the average isotopic composition of the solar system for elements heavier than lithium, we conclude that essentially all rocky materials in the inner solar system were enriched in ^(17)O and ^(18)O, relative to ^(16)O, by ~7%, probably via non–mass-dependent chemistry before accretion of the first planetesimals. ",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/25233,
    title ="Argon, krypton, and xenon in the bulk solar wind as collected\nby the Genesis mission",
    author = "Vogel, Nadia and Heber, Veronika S.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "75",
    number = "11",
    pages = "3057-3071",
    month = "June",
    year = "2011",
    
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20110906-132743767",
    note = "© 2011 Elsevier Ltd. Received 20 September 2010; accepted 25 February 2011. Associate editor: Gregory F. Herzog. Available online 2 March 2011. We would like to thank J.H. Allton and the entire Genesis curation team at Johnson Space Center, Houston, USA, for their great support with sample selection and cleaning. We greatly appreciate\nthe detailed and constructive reviews of H. Busemann, J.D.\nGilmour, and A.P. Meshik. Finally we would like to thank G.F. Herzog for the helpful comments and suggestions, and the editorial handling of the manuscript. This work was supported by the Swiss National Science Foundation. \n",
    revision_no = "11",
    abstract = "We present bulk solar wind isotopic and elemental ratios for Ar, Kr, and Xe averaged from up to 14 individual analyses on silicon targets exposed to the solar wind for ~2.3 years during NASA’s Genesis mission. All averages are given with 1σ standard errors of the means and include the uncertainties of our absolute calibrations. The isotopic ratios ^(86)Kr/^(84)Kr and ^(129)Xe/^(132)Xe are 0.303 ± 0.001 and 1.06 ± 0.01, respectively. The elemental ratios ^(36)Ar/^(84)Kr and ^(84)Kr/^(132)Xe are 2390 ± 120\nand 9.9 ± 0.3, respectively. Average fluxes of ^(84)Kr and ^(132)Xe in the bulk solar wind in atoms/(cm^2 s) are 0.166 ± 0.009 and 0.017 ± 0.001, respectively. The flux uncertainties also include a 2% uncertainty for the determination of the extracted areas. The bulk solar wind ^(36)Ar/^(38)Ar ratio of 5.50 ± 0.01 and the ^(36)Ar flux of 397 ± 11 atoms/(cm^2s) determined from silicon\ntargets agree well with the ^(36)Ar/^(38)Ar ratio and the ^(36)Ar flux determined earlier on a different type of target by Heber et al. (2009). A comparison of the solar wind noble gas/oxygen abundance ratios with those in the solar photosphere revealed a slight enrichment of Xe and, within uncertainties a roughly uniform depletion of Kr–He in the solar wind, possibly related to the first ionization potentials of the studied elements. Thus, the solar wind elemental abundances He–Kr display within uncertainties roughly photospheric compositions relative to each other. A comparison of the Genesis data with solar wind heavy noble gas data deduced from lunar regolith samples irradiated with solar wind at different times in the past reveals uniform ^(36)Ar/^(84)Kr ratios over the last 1–2 Ga but an increase of the ^(84)Kr/^(132)Xe ratio of about a factor of 2 during the same time span. The reason for this change in the solar wind composition remains unknown. ",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/38035,
    title ="Isotopic and elemental fractionation of solar wind implanted in the Genesis concentrator target characterized and quantified by noble gases",
    author = "Heber, Veronika S. and Wiens, Roger C.",
    journal = "Meteoritics and Planetary Science",
    volume = "46",
    number = "4",
    pages = "493-512",
    month = "April",
    year = "2011",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130419-103126504",
    note = "©  2011 The Meteoritical Society.\n\nReceived 22 July 2010; revision accepted 12 December 2010.\n\nWe thank NASA Discovery Mission Office for its support of the Genesis mission and the NASA Laboratory Analysis of Returned Samples Program Office for providing subsequent support. We greatly appreciate the support from Judith H. Allton and the entire Genesis curation team at Johnson Space\nCenter for sample selection. We are grateful to Yong Wang and the Los Alamos Ion Beam Materials Laboratory for performing the ion implants used in this work. We are very thankful for the comments and corrections provided by the referees Andrew Davis, Bernard Marty, Sasha Verchovsky and by the Associate Editor Marc Caffee. V. S. Heber acknowledges support by the Swiss National Science Foundation and NASA Cosmochemistry.",
    revision_no = "9",
    abstract = "We report concentrations and isotopic compositions of He, Ne, and Ar measured with high spatial resolution along a radial traverse of a silicon carbide (SiC) quadrant of the Genesis mission concentrator target. The Ne isotopic composition maps instrumental fractionation as a function of radial position in the target: the maximum observed isotopic fractionation is approximately 33‰ per mass unit between the center and periphery. The Ne fluence is enhanced by a factor of 43 at the target center and decreases to 5.5 times at the periphery relative to the bulk solar wind fluence. Neon isotopic profiles measured along all four arms of the \"gold cross\" mount which held the quadrants in the concentrator target demonstrate that the concentrator target was symmetrically irradiated during operation as designed. We used implantation experiments of Ne into SiC and gold to quantify backscatter loss and isotopic fractionation and compared measurements with numerical simulations from the code \"stopping and range of ions in matter.\" The ^(20)Ne fluence curve as a function of radial distance on the target may be used to construct concentration factors relative to bulk solar wind for accurate corrections for solar wind fluences of other light elements to be measured in the concentrator target. The Ne isotopic composition as a function of the radial distance in the SiC quadrant provides a correction for the instrumental mass-dependent isotopic fractionation by the concentrator and can be used to correct measured solar wind oxygen and nitrogen isotopic compositions to obtain bulk solar wind isotopic compositions.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/23081,
    title ="RIMS analysis of Ca and Cr in Genesis solar wind collectors",
    author = "Veryovkin, I. V. and Tripa, C. E.",
    journal = "Surface and Interface Analysis",
    volume = "43",
    number = "1-2",
    pages = "467-469",
    month = "January",
    year = "2011",
    
    issn = "0142-2421",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20110323-152613681",
    note = "© 2010 John Wiley & Sons, Ltd.\n\nReceived: 30 September 2009; Revised: 25 March 2010; Accepted: 26 March 2010; Published online in Wiley Online Library: 22 June 2010.\n\nThe authors wish to thank Andreas Wucher for helpful discussions. This work is supported by NASA through Grants NNH08AH761 and NNH08ZDA001N, by UChicago Argonne, LLC, under contract No. DE-AC02-06CH11357 and by the University of Newcastle.",
    revision_no = "16",
    abstract = "RIMS depth profiles have been measured for Cr and Ca in Genesis solar wind collector made from Si and compared to such measurements for ion-implanted Si reference material. The presence of surface contamination has been shown to be a significant factor influencing the total Ca and Cr fluence measured in the Genesis collectors. A procedure to remove the contaminant signal from these depth profiles using the reference material implanted with a minor isotope demonstrated that 36% of the measured Ca fluence in our Genesis sample comes from terrestrial contamination. ",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36637,
    title ="Solar Wind Abundances of C and O",
    author = "Heber, V. S. and Guan, Y.",
    journal = "Meteoritics and Planetary Science",
    volume = "45",
    number = "S1",
    pages = "A78",
    month = "July",
    year = "2010",
    doi = "10.1111/j.1945-5100.2010.01051.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130129-073104997",
    note = "© 2010 The Meteoritical Society. \n\nArticle first published online: 15 Jul. 2010.",
    revision_no = "11",
    abstract = "Quantitative understanding of solar wind (SW) elemental fractionation is required to improve knowledge of the solar nebula abundances from Genesis samples, in particular abundances of volatile elements, depleted in CI chondrites. Ratios of elements with low and high first ionization potential (FIP) in the solar wind, e.g., Fe/He, are higher than photospheric abundances. C, O, and N have intermediate FIP and are thus critical as to whether this fractionation is stepwise or gradual as a function of FIP.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36638,
    title ="Valence of Titanium in Ca-Al-Rich Inclusions:  Experimental Samples and Relevance to Natural CAIs",
    author = "Paque, J. M. and Sutton, S. R.",
    journal = "Meteoritics and Planetary Science",
    volume = "45",
    number = "S1",
    pages = "A161-A161",
    month = "July",
    year = "2010",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130129-073559453",
    note = "© 2010 The Meteoritical Society.\nArticle first published online: 15 Jul. 2010.\n",
    revision_no = "10",
    abstract = "Previous X-ray Absorption Near Edge Structure\n(XANES) Spectroscopy studies on spinels (sp) from Allende TS-34 [1, 2]\nhave shown them to contain little Ti^(3+), relative to Ti^(4+), in spite of being\nhosted by Ti^(3+)-enriched clinopyroxene (cpx). This suggests that the\nspinels are products of a more oxidizing environment.\n",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36646,
    title ="Analytical cosmochemistry: 1965-2010",
    author = "Burnett, D. S.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "74",
    number = "12",
    pages = "A129-A129",
    month = "June",
    year = "2010",
    
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130129-110635397",
    note = "© 2010 Published by Elsevier Ltd.\n",
    revision_no = "9",
    abstract = "Cosmochemistry is predominantly observational and\nanalytical. Many extraterrestrial materials are complex\nmixtures. Very small grains within these may carry unique\nsignatures of early solar system conditions, events, and\nprocesses. The isolation and analyses of presolar materials are\nthe best examples of this. Evolving from the days of mass\nspectra on strip charts analyzed with a magnifying glass, a 9H\npencil and a Marchant calculator, the development of the first\nmass spectrometers with computerized data acquisiton by\nWasserburg and Papanastassiou was driven by the recognition\nthat potentially unfavorable parent/daughter ratios in\nmeteoritic and lunar materials required another decimal point\nin the precision of isotopic ratios for geochronological\npurposes. The obvious importance of trace element and\nisotopic analysis in small areas of relatively rare, but not\nalways perfectly preserved, meteoritical materials such as Ca-\nAl-rich inclusions spurred the development of ion probes.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/17271,
    title ="Nitrogen isotopes in the recent solar wind from the analysis of Genesis targets: Evidence for large scale isotope heterogeneity in the early solar system",
    author = "Marty, Bernard and Zimmermann, Laurent",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "74",
    number = "1",
    pages = "340-355",
    month = "January",
    year = "2010",
    
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20100121-141034689",
    note = "© 2009 Elsevier.\n\nReceived 17 June 2009;  accepted 11 September 2009.  Associate editor: Gregory F. Herzog.  Available online 15 September 2009. \n\nWe are grateful to J.H. Allton, A.J.G. Jurewicz and the Genesis\nCuration team at Johnson Space Center, NASA, Houston (USA)\nfor excellent sample selection and preparation. We are also thankful\nto the Concentrator instrument team at Los Alamos National Laboratory\nfor providing blanks and information on the gold cross. F.\nGaboriau, LCPME, Vandoeuvre le`s Nancy (France) helped for\natomic force microscopy analysis of test samples. S. Sestak and\nI.A. Franchi did ozone cleaning of the samples at the Open University,\nMilton Keynes (UK). J.I. Matsuda kindly provided the\n3He/4He gas sample used in this study. We thank the members of\nthe Genesis Science Team for constructive interactions during the\nlast 6 years. The manuscript benefitted from stimulating reviews\nby A. Verchovsky, F. Robert and an anonymous reviewer, and from\ncareful editing by G. Herzog. This study was funded by Centre National\nd’Etudes Spatiales, Centre National de la Recherche Scientifique\n— Institut National des Sciences de l’Univers, Région\nLorraine, The Swiss National Science Foundation, and NASA\nthrough the Genesis mission.",
    revision_no = "20",
    abstract = "We have analyzed nitrogen, neon and argon abundances and isotopic ratios in target material exposed in space for 27 months to solar wind (SW) irradiation during the Genesis mission. SW ions were extracted by sequential UV (193 nm) laser ablation of gold-plated material, purified separately in a dedicated line, and analyzed by gas source static mass spectrometry. We analyzed gold-covered stainless steel pieces from the Concentrator, a device that concentrated SW ions by a factor of up to 50. Despite extensive terrestrial N contamination, we could identify a non-terrestrial, ^(15)N-depleted nitrogen end-member that points to a 40% depletion of ^(15)N in solar-wind N relative to inner planets and meteorites, and define a composition for the present-day Sun (^(15)N/^(14)N = [2.26 ± 0.67] × 10^(−3), 2σ), which is indistinguishable from that of Jupiter’s atmosphere. These results indicate that the isotopic composition of nitrogen in the outer convective zone of the Sun has not changed through time, and is representative of the protosolar nebula. Large ^(15)N enrichments due to e.g., irradiation, low temperature isotopic exchange, or contributions from ^(15)N-rich presolar components, are therefore required to account for inner planet values.\n\n",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/17144,
    title ="Noble gas composition of the solar wind as collected by the Genesis mission",
    author = "Heber, Veronika S. and Wieler, Rainer",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "73",
    number = "24",
    pages = "7414-7432",
    month = "December",
    year = "2009",
    
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20100112-110441285",
    note = "© 2009 Elsevier Ltd. Received 11 June 2009; accepted in revised form 14 September 2009; available online 23 September 2009. We are thankful for the great support from Judith H. Allton\nand the entire Genesis curation team at Johnson Space Center,\nHouston USA, for sample selection and cleaning. We appreciate\ndiscussions with Rolf Kipfer and Ansgar Grimberg. We thank\nNadia Vogel for discussion and correction of the paper. Detailed\nreviews by Jamie Gilmour, Roger Wiens and an anonymous reviewer\nare gratefully acknowledged. We acknowledge support by\nthe Swiss National Science Foundation and the NASA Discovery\nMission Office. V.S. Heber thanks Kevin McKeegan and NASA\nCosmochemistry to have been able to complete this work.",
    revision_no = "16",
    abstract = "We present the elemental and isotopic composition of noble gases in the bulk solar wind collected by the NASA Genesis sample return mission. He, Ne, and Ar were analyzed in diamond-like carbon on a silicon substrate (DOS) and ^(84),^(86)Kr and ^(129),^(132)Xe in silicon targets by UV laser ablation noble gas mass spectrometry. Solar wind noble gases are quantitatively retained in DOS and with exception of He also in Si as shown by a stepwise heating experiment on a flown DOS target and analyses on other bulk solar wind collector materials. Solar wind data presented here are absolutely calibrated and the error of the standard gas composition is included in stated uncertainties. The isotopic composition of the light noble gases in the bulk solar wind is as follows: ^3He/^4He: (4.64 ± 0.09) × 10^(−4), ^(20)Ne/^(22)Ne: 13.78 ± 0.03, ^(21)Ne/^(22)Ne: 0.0329 ± 0.0001, ^(36)Ar/^(38)Ar 5.47 ± 0.01. The elemental composition is:^4He/^(20)Ne: 656 ± 5, and ^(20)Ne/^(36)Ar 42.1 ± 0.3. Genesis provided the first Kr and Xe data on the contemporary bulk solar wind. The preliminary isotope and elemental composition is: ^(86)Kr/^(84)Kr: 0.302 ± 0.003, ^(129)Xe/^(132)Xe: 1.05 ± 0.02, ^(36)Ar/^(84)Kr 2390 ± 150, and ^(84)Kr/^(132)Xe 9.5 ± 1.0. The ^3He/^4He and the ^4He/^(20)Ne ratios in the Genesis DOS target are the highest solar wind values measured in exposed natural and artificial targets. The isotopic composition of the other noble gases and the Kr/Xe ratio obtained in this work agree with data from lunar samples containing “young” (~100 Ma) solar wind, indicating that solar wind composition has not changed within at least the last 100 Ma. Genesis could provide in many cases more precise data on solar wind composition than any previous experiment. Because of the controlled exposure conditions, Genesis data are also less prone to unrecognized systematic errors than, e.g., lunar sample analyses. The solar wind is the most authentic sample of the solar composition of noble gases, however, the derivation of solar noble gas abundances and isotopic composition using solar wind data requires a better understanding of fractionation processes acting upon solar wind formation.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36659,
    title ="Chromium Fluence Measurements in Genesis Samples Using A Nanosims",
    author = "Wang, J. and Nittler, L. R.",
    journal = "Meteoritics and Planetary Science",
    volume = "44",
    number = "S7",
    pages = "A213-A213",
    month = "July",
    year = "2009",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130129-134203786",
    note = "© 2009 The Meteoritical Society.\nArticle first published online: 26 Jan 2010.\n\n",
    revision_no = "9",
    abstract = "Our Sun holds most of the mass of the solar system\n(99.9%) and its chemical and isotopic composition thus provides the\nreference standard for astronomical, cosmochemical and geochemical\nstudies. The Genesis mission returned solar wind implanted samples for\nstudying solar wind composition. Previous studies of solar wind Cr fluence in\nGenesis samples showed over-estimates of it due to surface contamination\n[1–2]. We analyzed three different Si target samples (60040, 30877 and\n60490) by NanoSIMS. With smaller analysis area (10–15 µm^2 in a 30 µm^2\nrastered area) and meticulous cleaning procedures (sample 60490) [3], the\nsurface contamination of Cr can be avoided. We obtained an average Cr\nfluence value 3.3 ± 1.1 × 10^(10)atom/cm^2 (2σ).\n",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36650,
    title ="Diffusion of Solar Wind Noble Gases from Genesis Aluminum Collectors",
    author = "Mabry, J. C. and Meshik, A. P.",
    journal = "Meteoritics and Planetary Science",
    volume = "44",
    number = "S7",
    pages = "A128-A128",
    month = "July",
    year = "2009",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130129-113007598",
    note = "© 2009 The Meteoritical Society.\nArticle first published online: 26 Jan 2010.\nThis work was supported, in part, by NASA\ngrants NNJO4HI17G and NAG5-12885. Thanks to the entire Genesis team for making this work possible.",
    revision_no = "11",
    abstract = "The Genesis mission collected samples of solar wind\n(SW) over a two-year period and returned them to earth for high-precision\nlaboratory measurements [1]. The exact temperatures that the collectors\nreached during exposure to the SW is unknown, however preflight\nsimulations [2] and comparison of measurements from different target\nmaterials point to the potential for measurable losses due to thermally\nactivated diffusion. We have conducted a diffusion experiment on a similar\ntime scale as the Genesis mission to determine the diffusion parameters of the\naluminum collector materials and to quantify the changes in the measured\nratios due to diffusive losses. In this work we have studied the light noble\ngases: helium, neon, and argon.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36649,
    title ="Fractionation of MG Isotopes between the Sun’s Photosphere and the Solar Wind",
    author = "Jurewicz, A. J. G. and Hervig, R.",
    journal = "Meteoritics and Planetary Science",
    volume = "44",
    number = "S7",
    pages = "A104-A104",
    month = "July",
    year = "2009",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130129-112114528",
    note = "© 2009 The Meteoritical Society.\nArticle first published online: 26 Jan 2010.",
    revision_no = "12",
    abstract = "The Genesis mission goal is to precisely determine the\nelemental and isotopic composition of the solar photosphere through\nmeasurements of solar wind; the photospheric composition being a proxy for\nthe early solar nebula. So, how elements and isotopes are fractionated (or not)\nwhen accelerated out of the photosphere is fundamental to interpreting\nGenesis data.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36647,
    title ="Preliminary Nanosims Analysis of Carbon Isotope of Carbonates in Calcium-Aluminum-Rich Inclusions",
    author = "Guan, Y. and Paque, J. M.",
    journal = "Meteoritics and Planetary Science",
    volume = "44",
    number = "S7",
    pages = "A82",
    month = "July",
    year = "2009",
    doi = "10.1111/j.1945-5100.2009.tb01099.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130129-111130154",
    note = "© 2009 The Meteoritical Society. \n\nArticle first published online: 26 Jan 2010.",
    revision_no = "10",
    abstract = "Carbonate minerals observed in primitive meteorites are products of either terrestrial weathering or aqueous alteration in the early solar system. Most of the carbonate minerals in carbonaceous chondrites occur primarily as isolated grains in matrix, as crosscutting veins, or as replacement minerals in chondrules [e.g., 1, 2]. A few calcium-aluminum-rich inclusions (CAIs) have been reported containing carbonate minerals as well [2, 3]. The C and O isotopes of carbonates in carbonaceous chondrites, mostly measured by stepwise extraction of bulk samples with phosphoric acid [4–7], are largely distinctive from those of terrestrial carbonates, whereas textural and petrographic evidence indicates that some carbonates in primitive meteorites are terrestrial in origin [2]. This study attempts to investigate from the aspect of C isotope the origin of rare carbonate minerals in some CAIs. If of extraterrestrial origin, carbonates in CAIs can provide important information and constraints on the ubiquitous aqueous alteration process in the early solar system.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36676,
    title ="Solar wind Ar, Kr, and Xe abundances deduced from Genesis targets",
    author = "Vogel, N. and Heber, V. S.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "73",
    number = "13",
    pages = "A1391-A1391",
    month = "June",
    year = "2009",
    
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130130-075625782",
    note = "© 2009 Elsevier B.V. \n",
    revision_no = "11",
    abstract = "The Sun's composition is a proxy for that of the solar\nnebula, which serves as a reference baseline in earth and\nplanetary science. The Sun's composition can be inferred by\nanalyzing its outflowing particle stream, the solar wind (SW).\nThe Genesis mission returned targets irradiated with SW for\n~2 years [1], which allow to directly constrain modern SW Ar,\nKr, and Xe compositions. Such analyses could so far only be\nmade indirectly on SW irradiated regolith samples [2-4].",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36675,
    title ="The composition of noble gases in the solar wind as collected by Genesis: A proxy for solar nebula composition",
    author = "Heber, V. S. and Vogel, N.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "73",
    number = "13",
    pages = "A509-A509",
    month = "June",
    year = "2009",
    
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130130-075215424",
    note = "© 2009 Elsevier B.V.\n",
    revision_no = "10",
    abstract = "Genesis, a NASA sample return mission, collected solar\nwind (SW) in space for 2.5 years for precise elemental and\nisotopic analyses. SW matter originates from the photosphere\nand outer convective zone of the Sun and serves as a proxy of\nsolar nebula composition. One major objective of Genesis was\nto determine solar abundances and isotopic composition of\nvolatile elements. The solar composition of noble gases is\ndifficult to determine as they are depleted in primitive\nmeteorites and also not detectable in the photospheric\nspectrum due to their high excitation energies.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/15102,
    title ="The formation of boundary clinopyroxenes and associated glass veins in type B1 CAIs",
    author = "Paque, J. M. and Beckett, J. R.",
    journal = "Meteoritics and Planetary Science",
    volume = "44",
    number = "5",
    pages = "665-687",
    month = "May",
    year = "2009",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20090817-144815407",
    note = "© The Meteoritical Society, 2009. \n\n(Received 03 June 2008; revision accepted 13 February 2009) \n\nReviews by S. Simon and A. N. Krot were useful and appreciated. We thank Steve Simon and Larry Grossman for the loan of the section of TS-34 and Glenn MacPherson (Smithsonian Institution) for USNM Leoville 3537-2. This work was funded in part by NASA grants NNG04GG14G, NNG05GH797, and NAG5-11640. Portions of this work were also performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory in part under Contract W-7405-Eng-48 and in part under Contract DE-AC52-07NA27344.",
    revision_no = "18",
    abstract = "We used focused ion beam thin section preparation and scanning transmission electron microscopy (FIB/STEM) to examine the interfacial region between spinel and host melilite for spinel grains in type B1 inclusions from the Allende and Leoville carbonaceous chondrites. Boundary clinopyroxenes decorating spinel surfaces have compositions similar to those of coarser clinopyroxenes from the same region of the inclusion, suggesting little movement after formation. Host melilite displays no anomalous compositions near the interface and late-stage minerals are not observed, suggesting that boundary pyroxenes did not form by crystallization of residual liquid. Allende spinels display either direct spinel-melilite contact or an intervening boundary clinopyroxene between the two phases. Spinel-melilite interfacial regions in a Leoville B1 are more complex, with boundary clinopyroxene, as observed in Allende, but also variable amounts of glass, secondary calcite, perovskite, and an Mg-, Al-, OH-rich and Ca-, Si-poor crystalline phase that may be a layered double hydrate. One possible scenario of formation for the glass veins is that open system alteration of melilite produced a porous, hydrated aggregate of Mg-carpholite or sudoite + aluminous diopside that was shock melted and quenched to a glass. The hydrated crystalline phase we observed may have been a shocked remnant of the precursor phase assemblage, but is more likely to have formed later by alteration of the glass. In the mantle, boundary clinopyroxenes may have been crystallized from Ti-rich liquids formed by the direct dissolution of perovskite and an associated Sc-Zr-rich phase or as a reaction product between dissolving perovskite and liquid. In the core, any perovskite and associated Ti-enriched liquids that may have originally been present disappeared before the growth of boundary clinopyroxene, and the observed boundary clinopyroxene may have nucleated and grown from the liquid, along with the larger core clinopyroxene.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/16064,
    title ="Investigation of radiation enhanced diffusion of magnesium in substrates flown on the NASA genesis mission \n",
    author = "King, B. V. and Pellin, M. J.",
    journal = "Applied Surface Science",
    volume = "255",
    number = "4",
    pages = "1455-1457",
    month = "December",
    year = "2008",
    
    issn = "0169-4332",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20090925-130741038",
    note = "© 2008 Elsevier B.V.\nAvailable online 14 May 2008. \n",
    revision_no = "9",
    abstract = "The thermal diffusion of an Mg implant in Si has been measured with SIMS and compared to RIMS (resonant ionisation mass spectrometry) measurements of Mg implantation and diffusion in Si wafers exposed to solar wind irradiation in the NASA Genesis mission. The Genesis samples show much more surface segregation that the samples annealed in the laboratory, due to diffusion and segregation of the implanted Mg to the heavily damaged near surface regions of the Genesis wafers. This Mg transport has been modeled by solving a set of stiff differential equations and found to agree with RIMS measurements for a Mg interstitial migration energy of 0.7 eV.\n\n",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/16065,
    title ="MegaSIMS: a SIMS/AMS hybrid for measurement of the Sun’s oxygen isotopic composition \n",
    author = "Mao, Peter H. and Burnett, Donald S.",
    journal = "Applied Surface Science",
    volume = "255",
    number = "4",
    pages = "1461-1464",
    month = "December",
    year = "2008",
    
    issn = "0169-4332",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20090925-132008719",
    note = "© 2008 Elsevier B.V.\nAvailable online 15 May 2008.\nFunding for this work was provided by the NASA Discovery\nProgram as part of the Genesis Mission. Airlock design was\ncourtesy of John Craven at the University of Edinburgh; engineering\nof the airlock and sample stage was carried out by Richard Plue.",
    revision_no = "10",
    abstract = "One of the primary objectives of the Genesis sample return mission is to measure the oxygen isotopic composition of the Sun to permil-level precision. The returned samples pose a unique analytical challenge, and around the world, there has been parallel development of several competing techniques to make the oxygen measurement on the Genesis concentrator samples. At UCLA, we have developed a hybrid instrument: a secondary ion mass spectrometer (SIMS) front-end combined with an accelerator mass spectrometer (AMS), whose purpose is to eliminate molecular interferences via dissociation. We describe here the current status of the development of the instrument and the remaining issues to address before we request the Genesis samples for analysis.\n\n",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36688,
    title ="Argon, krypton, and xenon abundances in the solar wind measured in silicon from the genesis mission",
    author = "Heber, V. S. and Baur, H.",
    journal = "Meteoritics and Planetary Science",
    volume = "43",
    number = "S7",
    pages = "A53-A53",
    month = "July",
    year = "2008",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130130-112648868",
    note = "© 2008 The Meteoritical Society.\nArticle first published online: 26 Jan. 2010.\n",
    revision_no = "11",
    abstract = "Up to now solar wind (SW) abundances of Kr and Xe\nhave been exclusively determined using SW irradiated regolith [1]. Hence,\none of Genesis’s major objectives is to obtain the heavy noble gas\ncomposition of the present-day SW using artificial targets exposed to the SW\nfor 2.5 years. SW abundances will allow to study fractionation processes\nupon SW formation, e.g., due to the first ionization potential (FIP-effect) [2].\nThis is of importance to deduce solar abundances of noble gases and other\nelements from SW data. Solar, i.e., photospheric, abundances of noble gases\nare indirectly determined due to the lack of suitable lines in the spectrum.\nRecently, solar abundance estimates for Ne and Ar were strongly reduced\nwhereas Kr and Xe changed only slightly [3]. This led to a dramatic decrease\nof the solar Ar/Kr ratio by a factor of ~3 from the earlier value [4] of 2140. If\ntrue, this change would invalidate theories of heavy noble gas fractionation in\nthe SW identified with regolith data [1, 5]. The Kr and Xe composition in\npresent-day SW will enable us to reassess solar abundances and fractionation\ntheories. Thus, we concentrate here on abundances of Ar, Kr and Xe in the\nbulk SW.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57314,
    title ="Nitrogen isotopes in the recent solar wind: Further analysis of gold-plated concentrator frame from Genesis",
    author = "Marty, B. and Zimmermann, L.",
    journal = "Meteoritics and Planetary Science",
    volume = "43",
    number = "7",
    pages = "A90",
    month = "July",
    year = "2008",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150507-081618288",
    note = "© 2008 Meteoritical Society.",
    revision_no = "12",
    abstract = "Nitrogen, the fifth most abundant element in the\nuniverse, displays the largest (after H) stable isotope variations in the solar\nsystem materials (excluding pre-solar grains). Recently several studies\nconcluded that protosolar nebula N was depleted by ~400‰, from (i) the\ncombined ion probe analysis of H and N isotopes in lunar soil grains\n(δ^(15)N ≤240‰, [1]), (ii) the analysis of the Jupiter atmosphere by either\ninfrared spectroscopy [2] or in situ by the Galileo probe [3] and (iii) δ^(15)N of\n400‰ for osbornite (TiN) embedded in a CAI [4]. The Genesis mission\nsampled solar wind ions during 27 months in space by passive implantation\nof SW ions in targets made of pure material. Despite a hard landing of the\nsample capsule, target material could be recovered and analyzed.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/35582,
    title ="Constraints on Neon and Argon Isotopic Fractionation in Solar Wind",
    author = "Meshik, Alex and Mabry, Jennifer",
    journal = "Science",
    volume = "318",
    number = "5849",
    pages = "433-435",
    month = "October",
    year = "2007",
    doi = "10.1126/science.1145528 ",
    issn = "0036-8075",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20121120-142339436",
    note = "© 2007 American Association for the Advancement of Science.\n\nReceived for publication 22 May 2007; Accepted for publication 31 August 2007.\n\nWe acknowledge the support of the entire Genesis team\nin enabling this work. Portions of this work at Washington Univ. were supported by NASA grants (NNJ04HI17G and NAG5-12885).\n",
    revision_no = "20",
    abstract = "To evaluate the isotopic composition of the solar nebula from which the planets formed, the relation between isotopes measured in the solar wind and on the Sun's surface needs to be known. The Genesis Discovery mission returned independent samples of three types of solar wind produced by different solar processes that provide a check on possible isotopic variations, or fractionation, between the solar-wind and solar-surface material. At a high level of precision, we observed no significant inter-regime differences in ^(20)Ne/^(22)Ne or ^(36)Ar/^(38)Ar values. For ^(20)Ne/^(22)Ne, the difference between low- and high-speed wind components is 0.24 ± 0.37%; for ^(36)Ar/^(38)Ar, it is 0.11 ± 0.26%. Our measured ^(36)Ar/^(38)Ar ratio in the solar wind of 5.501 ± 0.005 is 3.42 ± 0.09% higher than that of the terrestrial atmosphere, which may reflect atmospheric losses early in Earth's history. ",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36703,
    title ="Depth profiling of genesis solar wind collectors with laser post-ionization SNMS",
    author = "Veryovkin, I. V. and Tripa, C. E.",
    journal = "Meteoritics and Planetary Science",
    volume = "42",
    number = "S8",
    pages = "A156-A156",
    month = "August",
    year = "2007",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130131-093725947",
    note = "© 2007 The Meteoritical Society.\nArticle first published online: 26 Jan. 2010.\nThis work is supported by the U.S. Department\nof Energy, BES-Materials Sciences, under Contract W-31-109-ENG-38 and by NASA under Work Orders W-19,895 and W-10,091.",
    revision_no = "12",
    abstract = "The samples returned to Earth by the Genesis mission of NASA’s\nDiscovery Program contain a record of the elemental and isotopic\nabundances of the solar wind. This record is implanted in the near-surface\nregion of the sample collectors allowing the solar wind material to be\ndistinguished from terrestrial contamination, which occurred due to the\nabrupt landing of the Genesis spacecraft. At Argonne National Laboratory,\nwe have recently developed a new laser post-ionization secondary neutral\nmass spectrometer (LPI–SNMS) called SARISA, which is capable of\naccurate measurements of ultra-trace concentrations of many metallic\nelements implanted in Genesis solar wind collectors. In this work, we will\nreport results of our measurements of abundances of Mg in two types of such\ncollectors, silicon and diamond-like carbon (film on silicon). These depth\nprofiling measurements were conducted in resonance-enhanced multi-photon\nionization (REMPI) regime, in two-color scheme with two Ti-sapphire postionization\nlasers tuned to 285.30 nm and 375.66 nm wavelengths, with the\nrepetition rate of 1 kHz.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/33702,
    title ="Experimental study of radium partitioning between anorthite and melt at 1 atm",
    author = "Miller, Sarah A. and Burnett, Donald S.",
    journal = "American Mineralogist",
    volume = "92",
    number = "8-9",
    pages = "1535-1538",
    month = "August",
    year = "2007",
    
    issn = "0003-004X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20120830-094514028",
    note = "© 2007 Mineralogical Society of America.\n\nManuscript received: March 19, 2007; manuscript accepted: May 10, 2007; manuscript handled by Bryan Chakoumakos.\n\nThe authors thank Haick Issaian and Andre Jefferson of the Caltech Safety Office for their time and expertise in assisting with safe handling of materials. NORIT Americas, Inc. generously donated activated charcoal for radon containment. Constructive reviews by Kari Cooper and Ken Sims improved the manuscript. This work was supported by NASA grants NAG5-11640 and NNG05GH79G to D. Burnett and NNH04AB47I to I. Hutcheon, NSF EAR-0239513 to P. Asimow\nand LLNL Laboratory Directed Research and Development funding. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract\nW-7405-ENG-48.",
    revision_no = "15",
    abstract = "We present the first experimental radium mineral/melt partitioning data, specifically between anorthite and a CMAS melt at atmospheric pressure. ^(226)Ra disequilibria are an important chronometer of recent magmatic activity. Ion microprobe measurement of coexisting anorthite and glass phases produces a molar D_Ra = 0.040 ± 0.006 and D_(Ra)/D_(Ba) = 0.24 ± 0.05 at 1400 °C. Our results indicate that lattice strain partitioning models fit the divalent (Ca, Sr, Ba, Ra) partition coefficient data of this study well, supporting previous work on crustal melting and magma chamber dynamics that has relied on such models to approximate radium partitioning behavior in the absence of experimentally determined values. ",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36697,
    title ="Light noble gas composition of different solar wind regimes: results from genesis",
    author = "Heber, V. S. and Baur, H.",
    journal = "Meteoritics and Planetary Science",
    volume = "42",
    number = "S8",
    pages = "A63-A63",
    month = "August",
    year = "2007",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130130-151230007",
    note = "© 2007 The Meteoritical Society. Article first published online: 26 Jan. 2010.\n",
    revision_no = "11",
    abstract = "The Genesis mission provided samples of solar wind\n(SW) from different regions on the Sun. These SW regime samples are\nimportant in understanding fractionation processes upon formation and\nacceleration of the SW to ultimately deduce solar composition from SW\nvalues. We present He and Ne isotopic and elemental compositions of the\nbulk SW (SW of entire collection period) and the 3 major SW regimes: slow\n(from the ecliptic plane, emanating from above streamers), fast (emanating\nfrom coronal holes), and coronal mass ejections (CME). At the conference\nwe will also present Ar data.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36704,
    title ="Nanosims measurements of solar wind Mg, Fe, and Cr fluences",
    author = "Wang, J. and Nittler, L. R.",
    journal = "Meteoritics and Planetary Science",
    volume = "42",
    number = "S8",
    pages = "A160",
    month = "August",
    year = "2007",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130131-094242068",
    note = "© 2007 The Meteoritical Society.\nArticle first published online: 26 Jan. 2010.\nThis work is supported by NASA grant NNX07AG19G.",
    revision_no = "10",
    abstract = "The chemical composition of the Sun provides the\nreference standard for a wide variety of astronomical, cosmochemical, and\ngeochemical studies. To better determine the solar composition, the Genesis\nspacecraft collected solar wind at the L1 point in the space for 27 months\nprior to returning samples to Earth in September 2004. Prior ion probe\nanalyses of Genesis samples have found discrepant results for the Mg and Fe\nsolar wind fluences from different collector materials [1]. We report\nmeasurements of Mg, Fe, and Cr depth profiles in Genesis diamond-like C\nsample 60062 using the Carnegie Institution Cameca NanoSIMS 50L ion\nmicroprobe. Our results for Mg and Fe are similar to previous analyses of the\nsame sample using different instruments.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36702,
    title ="Origin of boundary clinopyroxenes between spinel and melilite in type B1 CAIs",
    author = "Paque, J. M. and Ishii, H. A.",
    journal = "Meteoritics and Planetary Science",
    volume = "42",
    number = "S8",
    pages = "A121-A121",
    month = "August",
    year = "2007",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130131-093304456",
    note = "© 2007 The Meteoritical Society.\nArticle first published online: 26 Jan. 2010.\n",
    revision_no = "11",
    abstract = "Small (<5 μm) boundary clinopyroxenes (b-cpx) on\nspinel (sp) inclusions in melilite (mel) are ubiquitous in the type B1 CAIs.\nB-cpx on sp in high-Åk mel in the core of the inclusion could be explained by\ncrystallization, either initial or during remelting. However, b-cpx on sp\ninclusions in low-Åk mantle mel are not readily explained in this way\nbecause mantle mel crystallized and incorporated b-cpx long before the\nappearance of clinopyroxene (cpx) in the crystallization sequence. To further\nconstrain the crystallization and/or alteration processes, and to test the\nhypothesis that b-cpx were formed from melt inclusions, we examined\nthe sp/mel interface of four sp in Leoville and Allende CAIs using FIB/TEM.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36700,
    title ="Preliminary studies of Xe and Kr from the Genesis polished aluminium collector",
    author = "Meshik, A. P. and Hohenberg, C. M.",
    journal = "Meteoritics and Planetary Science",
    volume = "42",
    number = "S8",
    pages = "A105-A105",
    month = "August",
    year = "2007",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130130-154039748",
    note = "© 2007 The Meteoritical Society.\nArticle first published online: 26 Jan. 2010.\nSupported by NASA grant NNJ04HI17G.",
    revision_no = "11",
    abstract = "Low solar wind (SW) abundances of Xe and Kr require\na large collector area to provide measurable quantities of these rare gases.\nOriginally we planned to use large areas of Al on Sapphire (AloS) collectors,\nbut the hard landing of Genesis fractured these collectors, changing our initial\nplans. The only large, relatively intact, surface exposed to SW was the\nkidney-shaped polished aluminum T6-6061 alloy (AlK) designed to serve as\na thermal shield rather than a SW collector. Here we describe what has been\ndone and the problems remaining to be solved for optimized Xe and Kr\nabundances and isotopic compositions from the AlK.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36698,
    title ="SIMS results for solar wind elemental abundances from genesis collectors",
    author = "Jurewicz, A. J. G. and Burnett, D. S.",
    journal = "Meteoritics and Planetary Science",
    volume = "42",
    number = "S8",
    pages = "A80-A80",
    month = "August",
    year = "2007",
    doi = " 10.1111/j.1945-5100.2007.tb00601.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130130-151743924",
    note = "© 2007 The Meteoritical Society.",
    revision_no = "10",
    abstract = "Solar wind elemental abundances are a major Genesis science objective. Spacecraft studies have shown that elements with first ionization potential (FIP) > 9 eV are fractionated relative to those with lower FIP compared with the solar photosphere; however, among elements with FIP < 9eV (which make up most of the terrestrial planets) there is no evidence of fractionation. A major goal of Genesis is to provide a higher precision test of the lack of fractionation for FIP < 9eV.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57389,
    title ="Solar wind Mg, Cr and Fe abundances in diamond-like carbon collector from Genesis mission",
    author = "Wang, J. and Nittler, L. R.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "71",
    number = "S15",
    pages = "A1085",
    month = "August",
    year = "2007",
    doi = "10.1016/j.gca.2007.06.029",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150508-150109913",
    note = "© 2007 Published by Elsevier Ltd. Available online 24 July 2007.",
    revision_no = "10",
    abstract = "The chemical composition of the Sun provides the reference standard for a wide variety of astronomical, cosmochemical and geochemical studies. To better determine the solar composition, the Genesis spacecraft collected solar wind at the L1 point in space for 27 months from December 2001 to April 2004. Prior SIMS analyses of Genesis samples have found discrepant results for the Mg and Fe solar wind fluences from different collector materials (Burnett et al., 2007).",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36699,
    title ="Solar wind argon from Genesis alos regime collectors",
    author = "Mabry, J. C. and Meshik, A. P.",
    journal = "Meteoritics and Planetary Science",
    volume = "42",
    number = "S8",
    pages = "A95-A95",
    month = "August",
    year = "2007",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130130-152240689",
    note = "© 2007 The Meteoritical Society. Article first published online: 26 Jan. 2010. Supported by NASA grants NNJO4HI17G and NAG5-12885.",
    revision_no = "10",
    abstract = "Determining solar noble gas isotopic ratios are one piece\nof the puzzle needed to constrain models of the evolution of terrestrial\nplanets, as well as to understand solar composition and processes. Solar wind\n(SW) remains the best available source of solar material, even though there is\npotential for fractionation between true solar values and the solar wind. Here\nwe will focus on SW argon.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/19867,
    title ="Composition of Light Solar Wind Noble Gases in the Bulk Metallic Glass flown on the Genesis Mission",
    author = "Grimberg, A. and Burnett, D. S.",
    journal = "Space Science Reviews",
    volume = "130",
    number = "1-4",
    pages = "293-300",
    month = "June",
    year = "2007",
    doi = "10.1007/s11214-007-9150-1",
    issn = "0038-6308",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20100910-112210816",
    note = "© 2007 Springer Science+Business Media, Inc. \n\nReceived: 20 December 2006; Accepted: 1 February 2007; Published online: 22 March 2007. \n\nWe would like to thank R.A. Mewaldt, G.M. Mason, C.M.S. Cohen, R.A. Leske, and M.E.Wiedenbeck for providing suprathermal fluence data from ACE, F. Bühler for valuable discussions, and S. Tosatti and O.J. Homan for XPS and plasma cleaning of the BMG. We also would like to thank the entire Genesis team. This work was supported by the Swiss National Science Foundation and NASA.",
    revision_no = "20",
    abstract = "We discuss data of light noble gases from the solar wind implanted into a metallic glass target flown on the Genesis mission. Helium and neon isotopic compositions of the bulk solar wind trapped in this target during 887 days of exposure to the solar wind do not deviate significantly from the values in foils of the Apollo Solar Wind Composition experiments, which have been exposed for hours to days. In general, the depth profile of the Ne isotopic composition is similar to those often found in lunar soils, and essentially very well reproduced by ion-implantation modelling, adopting the measured velocity distribution of solar particles during the Genesis exposure and assuming a uniform isotopic composition of solar wind neon. The results confirm that contributions from high-energy particles to the solar wind fluence are negligible, which is consistent with in-situ observations. This makes the enigmatic “SEP-Ne” component, apparently present in lunar grains at relatively large depth, obsolete. ^(20)Ne/^(\u200922)Ne ratios in gas trapped very near the metallic glass surface are up to 10% higher than predicted by ion implantation simulations. We attribute this superficially trapped gas to very low-speed, current-sheet-related solar wind, which has been fractionated in the corona due to inefficient Coulomb drag.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/20331,
    title ="Elemental Abundances of the Bulk Solar Wind: Analyses from Genesis and ACE",
    author = "Reisenfeld, D. B. and Burnett, D. S.",
    journal = "Space Science Reviews",
    volume = "130",
    number = "1-4",
    pages = "79-86",
    month = "June",
    year = "2007",
    
    issn = "0038-6308",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20101007-094550306",
    note = "© 2007 Springer Science+Business Media B.V.\nReceived: 8 February 2007; Accepted: 15 May 2007; Published online: 6 July 2007.\n\nThe authors thank the NASA Discovery Program for their support of Genesis.",
    revision_no = "18",
    abstract = "Analysis of the Genesis samples is underway. Preliminary elemental abundances based on Genesis sample analyses are in good agreement with in situ-measured elemental abundances made by ACE/SWICS during the Genesis collection period. Comparison of these abundances with those of earlier solar cycles indicates that the solar wind composition is relatively stable between cycles for a given type of flow. ACE/SWICS measurements for the Genesis collection period also show a continuum in compositional variation as a function of velocity for the quasi-stationary flow that defies the simple binning of samples into their sources of coronal hole (CH) and interstream (IS). ",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/20426,
    title ="Solar and Solar-Wind Composition Results from the Genesis Mission",
    author = "Wiens, R. C. and Burnett, D. S.",
    journal = "Space Science Reviews",
    volume = "130",
    number = "1-4",
    pages = "161-171",
    month = "June",
    year = "2007",
    doi = "10.1007/s11214-007-9227-x",
    issn = "0038-6308",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20101014-101514488",
    note = "© 2007 Springer Science+Business Media B.V. \n\nReceived: 21 February 2007; Accepted: 29 May 2007; Published online: 3 August 2007. \n\nWe thank the NASA Discovery Mission program, the NASA Jet Propulsion Laboratory, and Lockheed-Martin Astronautics, for their support of the Genesis mission. Thousands of people contributed to the mission, and our thanks also go to all of them. We also thank the organizers of this ISSI symposium.",
    revision_no = "22",
    abstract = "The Genesis mission returned samples of solar wind to Earth in September 2004 for ground-based analyses of solar-wind composition, particularly for isotope ratios. Substrates, consisting mostly of high-purity semiconductor materials, were exposed to the solar wind at L1 from December 2001 to April 2004. In addition to a bulk sample of the solar wind, separate samples of coronal hole (CH), interstream (IS), and coronal mass ejection material were obtained. Although many substrates were broken upon landing due to the failure to deploy the parachute, a number of results have been obtained, and most of the primary science objectives will likely be met. These objectives include He, Ne, Ar, Kr, and Xe isotope ratios in the bulk solar wind and in different solar-wind regimes, and ^(15)N/^(14)N and ^(18)O/^(17)O/^(16)O to high precision. The greatest successes to date have been with the noble gases. Light noble gases from bulk solar wind and separate solar-wind regime samples have now been analyzed. Helium results show clear evidence of isotopic fractionation between CH and IS samples, consistent with simplistic Coulomb drag theory predictions of fractionation between the photosphere and different solar-wind regimes, though fractionation by wave heating is also a possible explanation. Neon results from closed system stepped etching of bulk metallic glass have revealed the nature of isotopic fractionation as a function of depth, which in lunar samples have for years deceptively suggested the presence of an additional, energetic component in solar wind trapped in lunar grains and meteorites. Isotope ratios of the heavy noble gases, nitrogen, and oxygen are in the process of being measured.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36941,
    title ="The Genesis Solar Wind Concentrator Target: Mass Fractionation Characterised by Neon Isotopes",
    author = "Heber, V. S. and Wiens, R. C.",
    journal = "Space Science Reviews",
    volume = "130",
    number = "1-4",
    pages = "309-316",
    month = "June",
    year = "2007",
    
    issn = "0038-6308",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130215-090220551",
    note = "© 2007 Springer Science+Business Media, Inc. \nReceived: 22 December 2006; Accepted: 26 March 2007; Published online: 15 May 2007.\nWe acknowledge the financial support by the Swiss National Science Foundation. We\nthank for the support by the NASA Discovery Mission Office.",
    revision_no = "12",
    abstract = "The concentrator on Genesis provided samples of increased fluences of solar wind ions for precise determination of the oxygen isotopic composition. The concentration process caused mass fractionation as a function of the radial target position. This fractionation was measured using Ne released by UV laser ablation and compared with modelled Ne data, obtained from ion-trajectory simulations. Measured data show that the concentrator performed as expected and indicate a radially symmetric concentration process. Measured concentration factors are up to ∼30 at the target centre. The total range of isotopic fractionation along the target radius is 3.8%/amu, with monotonically decreasing ^(20)Ne/^(22)Ne towards the centre, which differs from model predictions. We discuss potential reasons and propose future attempts to overcome these disagreements. ",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36961,
    title ="Zoning patterns of Fe and V in spinel from a type B Ca-Al-rich inclusion: Constraints on subsolidus thermal history",
    author = "Paque, J. M. and Burnett, D. S.",
    journal = "Meteoritics and Planetary Science",
    volume = "42",
    number = "6",
    pages = "899-912",
    month = "June",
    year = "2007",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130215-133921432",
    note = "© 2007 The Meteoritical Society.\nReceived 05 June 2006; revision accepted 12 January 2007.\nArticle first published online: 26 Jan. 2010.\nComments by H. C. Connolly were useful\nand appreciated, in addition to helpful reviews from S. Simon,\nH. C. Connolly, and J. Aléon. The TS-34 section used in this\nstudy was generously provided by L. Grossman and S. Simon.\nThis work was supported by NASA grants NNG04GG14G,\nNNG05GH79Z, and NAG5-11640.",
    revision_no = "9",
    abstract = "We obtained two-dimensional concentration maps for the minor elements Fe and V in 21 spinel crystals in the Allende type B1 inclusion TS-34 with a 4–5 μm resolution. Locally high concentrations of Fe occur along at least one edge of the spinels and decrease toward the center of the grains. Enrichment in V can also occur along edges or at corners. In general, there is no overall correlation of the Fe and V distributions, but in local regions of two grains, the V and Fe distributions are correlated, strongly suggesting a local source for both elements. In these two grains, opaque assemblages are present that appear to locally control the V distributions. This, coupled with previous work, suggests that prior to alteration, TS-34 contained V-rich metal. Oxidation of this metal during alteration can account for the edge/corner V enrichments, but provide only minor FeO contributions, explaining the overall lack of correlation between Fe and V. Most of the FeO appears to have been externally introduced along spinel boundaries during alteration. These alteration phases served as sources for diffusion of FeO into spinel. FeO distributions in spinel lead to a mean attenuation length of ~8 μm and, using literature diffusion coefficients in isothermal and exponential cooling approximations for peak temperatures in the range 600–700°C, this leads to a time scale for calcium-aluminum-rich inclusion (CAI) alteration in the range of decades to centuries.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/35531,
    title ="NASA Returns Rocks from a Comet",
    author = "Burnett, Don S.",
    journal = "Science",
    volume = "314",
    number = "5806",
    pages = "1709-1710",
    month = "December",
    year = "2006",
    
    issn = "0036-8075",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20121119-100451751",
    note = "© 2006 American Association for the Advancement of Science.\n\n",
    revision_no = "11",
    abstract = "Cometary particles returned by the Stardust Discovery Mission are primarily silicate materials of solar system origin. Some of the grains were formed at high temperatures close to the Sun, but then transported far out to the Kuiper belt region of the solar system before being incorporated in the comet. ",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/35522,
    title ="Solar Wind Neon from Genesis: Implications for the Lunar Noble Gas Record",
    author = "Grimberg, Ansgar and Baur, Heinrich",
    journal = "Science",
    volume = "314",
    number = "5802",
    pages = "1133-1135",
    month = "November",
    year = "2006",
    
    issn = "0036-8075",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20121116-133102676",
    note = "© 2006 American Association for the Advancement of Science. \n\nReceived for publication 7 August 2006; Accepted for publication 4 October 2006.\n\nThe BMG experiment was made possible by the support of\nthe entire Genesis Project at the Jet Propulsion Laboratory\n(JPL), Los Alamos National Laboratory, and Lockheed Martin,\nwith special thanks to the JPL Genesis Canister design\nteam, headed by D. Sevilla, and to the Genesis curation team at Johnson Space Center. We also thank I. Leya for constructive comments and suggestions, O. J. Homan for plasma-cleaning the BMG, and S. Tosatti for nondestructive x-ray photoelectron spectroscopy surface analyses. This study was financially supported by the Swiss National Science Foundation and the Genesis Project.",
    revision_no = "14",
    abstract = "Lunar soils have been thought to contain two solar noble gas components with distinct isotopic composition. One has been identified as implanted solar wind, the other as higher-energy solar particles. The latter was puzzling because its relative amounts were much too large compared with present-day fluxes, suggesting periodic, very high solar activity in the past. Here we show that the depth-dependent isotopic composition of neon in a metallic glass exposed on NASA's Genesis mission agrees with the expected depth profile for solar wind neon with uniform isotopic composition. Our results strongly indicate that no extra high-energy component is required and that the solar neon isotope composition of lunar samples can be explained as implantation-fractionated solar wind. ",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/33772,
    title ="Determination of melt influence on divalent element partitioning between anorthite and CMAS melts",
    author = "Miller, Sarah A. and Asimow, Paul D.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "70",
    number = "16",
    pages = "4258-4274",
    month = "August",
    year = "2006",
    
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20120831-112239557",
    note = "© 2006 Elsevier Inc.\nReceived 12 January 2006; accepted in revised form 16 June 2006.\nWe thank Ma Chi and Julie Paque for electron microprobe\nassistance, as well as Ian Hutcheon and Doug Phinney\nfor help with ion microprobe analyses that allowed us\nto select our analytical course of action in this study. The\nmanuscript benefited from the dedicated reviews of Alexandre\nCorgne and an anonymous reviewer. This work was supported by NASA grants NAG5-11640 and NNG05GH79G to D. Burnett and NSF EAR-0239513 to P. Asimow.\nAssociate editor: F.J. Ryerson",
    revision_no = "13",
    abstract = "We propose a theory for crystal-melt trace element partitioning that considers the energetic consequences of crystal-lattice strain, of multi-component major-element silicate liquid mixing, and of trace-element activity coefficients in melts. We demonstrate application of the theory using newly determined partition coefficients for Ca, Mg, Sr, and Ba between pure anorthite and seven CMAS liquid compositions at 1330 °C and 1 atm. By selecting a range of melt compositions in equilibrium with a common crystal composition at equal liquidus temperature and pressure, we have isolated the contribution of melt composition to divalent trace element partitioning in this simple system. The partitioning data are fit to Onuma curves with parameterizations that can be thermodynamically rationalized in terms of the melt major element activity product (a_(Al_2O_3))(a_(SiO_2_)^2 and lattice strain theory modeling. Residuals between observed partition coefficients and the lattice strain plus major oxide melt activity model are then attributed to non-ideality of trace constituents in the liquids. The activity coefficients of the trace species in the melt are found to vary systematically with composition. Accounting for the major and trace element thermodynamics in the melt allows a good fit in which the parameters of the crystal-lattice strain model are independent of melt composition.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57381,
    title ="Argon and neon in Genesis aluminum-coated sapphire collectors from regime arrays",
    author = "Mabry, J. C. and Meshik, A. P.",
    journal = "Meteoritics and Planetary Science",
    volume = "41",
    number = "S8",
    pages = "A109",
    month = "August",
    year = "2006",
    doi = "10.1111/j.1945-5100.2006.tb00996.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150508-130358529",
    note = "© 2006 The Meteoritical Society. \n\nSupported by NASA grants NNJO4HIl7G and NAG5-l2885.",
    revision_no = "9",
    abstract = "Here we report Ar results from the aluminum on sapphire (AloS) bulk regime samples, from which Ne results were obtained [1]. Ar measurements from other regimes are in progress.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36713,
    title ="Depth-dependent fractionation of light solar wind noble gases in a Genesis target",
    author = "Grimberg, A. and Bühler, F.",
    journal = "Meteoritics and Planetary Science",
    volume = "41",
    number = "S8",
    pages = "A67-A67",
    month = "August",
    year = "2006",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130131-132640854",
    note = "© 2006 The Meteoritical Society.\n\nArticle first published online: 26 Jan. 2010.",
    revision_no = "8",
    abstract = "We analyzed light noble gases in a bulk metallic glass (BMG) that was\nexposed to solar wind (SW) irradiation on Genesis for its total exposure time\nand all SW regimes [1]. The BMG was especially designed to look for a\nputative solar energetic particle (SEP) component, reported to be present in\nlunar soils [2], by using the closed system stepwise etching (CSSE)\ntechnique. Here we present the depth distribution of He and Ne isotopes and\ndiscuss different processes leading to the observed fractionation patterns.\nMoreover, this will be compared with measurements of Ar isotopes that are\nactually in progress.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36714,
    title ="Mass-fractionation induced by the Genesis solar wind concentrator: Analysis of neon isotopes by UV laser ablation",
    author = "Heber, V. S. and Wiens, R. C.",
    journal = "Meteoritics and Planetary Science",
    volume = "41",
    number = "S8",
    pages = "A72-A72",
    month = "August",
    year = "2006",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130131-134926701",
    note = "© 2006 The Meteoritical Society.\nArticle first published online: 26 Jan. 2010.",
    revision_no = "11",
    abstract = "The solar wind (SW) concentrator, a key instrument onboard the\nGenesis mission, was designed to provide larger fluences of implanted SW\nfor precise isotope analyses of oxygen and nitrogen [1]. SW ions in the mass\nrange 4–28 amu were accelerated and focused on a “concentrator target” by\nan electrostatic mirror. This concentration process caused some instrumental\nmass fractionation of the implanted SW ions as function of the radial position\non the target. Correction of this fractionation will be based on a combination\nof the measured radial fractionation of Ne isotopes with results of simulations\nof the implantation process using the actual performance of the concentrator\nand the SW conditions during exposure. Here we present He and Ne\nabundance and Ne isotopic composition data along one arm of the gold cross\nthat framed the 4 concentrator subtargets.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57387,
    title ="Solar neon released from Genesis aluminum collector duriung stepped uv-laser extraction and step-wise pyrolysis",
    author = "Meshik, A. and Marrocchi, Y.",
    journal = "Meteoritics and Planetary Science",
    volume = "41",
    number = "S8",
    pages = "A121",
    month = "August",
    year = "2006",
    doi = "10.1111/j.1945-5100.2006.tb00996.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150508-142837896",
    note = "© 2006 The Meteoritical Society. \n\nSupported by NASA grants NNJO4HI17G and NAG5-12885.",
    revision_no = "8",
    abstract = "Earlier this year we reported results of UV-laser stepped raster extractions of Ne and He from Genesis' Al-collector [l]. Since then, using pyrolysis of a 0.005 cm^2 fragment of this material left from the earlier study, we have estimated the efficiency of the UV-laser extraction to be at least 95%. We also analyzed Ne released from the Al-collector by means of stepped pyrolysis. Here we compare these new data with stepped UV-laser extraction and the CSSE results [2]. Figure 1 shows the ^(20)Ne/^(22)Ne ratio extracted from Genesis collectors using these three techniques.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36712,
    title ="The solar wind FE/MG ratio",
    author = "Burnett, D. S. and Jurewicz, A. J. G.",
    journal = "Meteoritics and Planetary Science",
    volume = "41",
    number = "S8",
    pages = "A33",
    month = "August",
    year = "2006",
    doi = "10.1111/j.1945-5100.2006.tb00996.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130131-131759052",
    note = "© 2006 The Meteoritical Society.",
    revision_no = "10",
    abstract = "To meet the Genesis mission goal for improved solar elemental abundances, we need to address the issue of fractionation of the abundances of elements in the solar wind compared to the solar photosphere. There is a well-established depletion of elements in the solar wind with high first ionization potential (FIP > 9eV) compared to lower FIP elements, but there is no evidence for fractionation between lower FIP elements.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/3959,
    title ="Primary U distribution in scleractinian corals and its implications for U series dating",
    author = "Robinson, Lauren F. and Adkins, Jess F.",
    journal = "Geochemistry, Geophysics, Geosystems",
    volume = "7",
    number = "5",
    pages = "Q05022",
    month = "May",
    year = "2006",
    
    issn = "1525-2027",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:ROBggg06",
    note = "Copyright 2006 by the American Geophysical Union. \n\nReceived 6 September 2005; accepted 10 March 2006; published 24 May 2006 \n\nWe gratefully acknowledge The Comer Foundation for Abrupt Climate Change and the helpful comments of two anonymous reviewers.",
    revision_no = "5",
    abstract = "In this study we use microsampling techniques to explore diagenetic processes in carbonates. These processes are important as they can affect the accuracy of U series chronometry. Fission track maps of deep-sea scleractinian corals show a threefold difference between the minimum and maximum [U] in modern corals, which is reduced to a factor of 2 in fossil corals. We use micromilling and MC-ICP-MS to make detailed analyses of the [U] and δ234Uinitial distributions in corals from 218 ka to modern. Within each fossil coral we observe a large range of δ234Uinitial values, with high δ234Uinitial values typically associated with low [U]. A simple model shows that this observation is best explained by preferential movement of alpha-decay produced 234U atoms (alpha-recoil diffusion). Open-system addition of 234U may occur when alpha-recoil diffusion is coupled with a high [U] surface layer, such as organic material. This process can result in large, whole-coral δ234Uinitial elevations with little effect on the final age. The diagenetic pathways that we model are relevant to both shallow-water and deep-sea scleractinian corals since both exhibit primary [U] heterogeneity and may be subject to U addition.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57380,
    title ="Solar wind noble gases - Preliminary results from bulk metallic glass flown on Genesis\n",
    author = "Grimberg, A. and Bühler, F.",
    journal = "Meteoritics and Planetary Science",
    volume = "40",
    number = "S9",
    pages = "S60",
    month = "September",
    year = "2005",
    doi = "10.1111/j.1945-5100.2005.tb00422.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150508-124557922",
    note = "© 2005 The Meteoritical Society.",
    revision_no = "8",
    abstract = "The solar wind (SW) is the major source of information to study the solar composition of volatile elements. It provides insights about the Sun's present state, its evolution and the composition of the proto-solar nebula. SW noble gases can be used to study processes causing fractionation between the Sun and the SW. Moreover they are useful to determine compositional variations for distinct SW energy regimes including the high energy SEP component apparently abundant in lunar samples [I]. We will present noble gas data collected on Genesis [2] with a bulk  metallic glass target (BMG) [3].",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/33725,
    title ="Melt thermodynamics and divalent element partitioning between anorthite and CMAS liquids",
    author = "Miller, S. A. and Asimow, Paul D.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "69",
    number = "10",
    pages = "A822",
    month = "May",
    year = "2005",
    
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20120830-152746549",
    note = "© 2005 Pergamon-Elsevier Science Ltd.",
    revision_no = "14",
    abstract = "Quantifying the effect of melt composition on trace\nelement partitioning in natural systems has been hampered by\ncorrelated variations in mineral chemistry, temperature, and\npressure. We have isolated the influence of melt composition\non divalent element (Mg, Ca, Sr, Ba) partitioning between\nstoichiometric anorthite and a range of synthetic melts. Data were obtained from electron microprobe analysis of anorthite rims from dynamic crystallization experiments. Melt compositions contain near constant SiO_2, CaO/Al_2O_3 ranging from 0.8-1.6, and MgO from 1-15 wt. %. Holding X_(mineral), T, and P constant, we observe partitioning behavior that varies systematically with melt chemistry.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51562,
    title ="Genesis capsule yields solar wind samples",
    author = "Wiens, Roger C. and Burnett, Donald S.",
    journal = "Eos",
    volume = "85",
    number = "47",
    pages = "497-498",
    month = "November",
    year = "2004",
    doi = "10.1029/2004EO470003",
    issn = "0096-3941",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141111-101851462",
    note = "© 2004 American Geophysical Union.",
    revision_no = "10",
    abstract = "NASA's Genesis capsule, carrying the first samples ever returned from beyond the Moon, took a hard landing in the western Utah desert on 8 September after its parachutes failed to deploy Despite the impact, estimated at 310 km per hour, some valuable solar wind collector materials have been recovered. With these samples, the Genesis team members are hopeful that nearly all of the primary science goals may be met.\n\nThe Genesis spacecraft was launched in August 2001 to collect and return samples of solar wind for precise isotopic and elemental analysis. The spacecraft orbited the Earth-Sun Lagrangian point (LI), ˜1.5 million km sunward of Earth, for 2.3 years. It exposed ultrapure materials—including wafers of silicon, silicon carbide, germanium, chemically deposited diamond, gold, aluminum, and metallic glass— to solar wind ions, which become embedded within the substrates' top 100 nm of these materials.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57265,
    title ="Solar and solar-wind isotopic compositions",
    author = "Wiens, Roger C. and Bochsler, Peter",
    journal = "Earth and Planetary Science Letters",
    volume = "222",
    number = "3-4",
    pages = "697-712",
    month = "June",
    year = "2004",
    doi = "10.1016/j.epsl.2004.03.025",
    issn = "0012-821X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-102038675",
    note = "© 2004 Elsevier B.V.\n\nReceived 26 November 2003; received in revised form 5 March 2004; accepted 21 March 2004.\n\nConstructive comments were given by R.O. Pepin, F. Buehler and J. Gosling. Helpful reviews by R. Wieler, T. Zurbuchen, and R. von Steiger, and editorial assistance by A. Halliday were greatly appreciated. Work on this manuscript at Los Alamos was supported by NASA contract W-19,272 and at Bern by the Swiss National Science Foundation.",
    revision_no = "11",
    abstract = "With only a few exceptions, the solar photosphere is thought to have retained the mean isotopic composition of the original solar nebula, so that, with some corrections, the photosphere provides a baseline for comparison of all other planetary materials. There are two sources of information on the photospheric isotopic composition: optical observations, which have succeeded in determining a few isotopic ratios with large uncertainties, and the solar wind, measured either in situ by spacecraft instruments or as implanted ions into lunar or asteroidal soils or collection substrates. Gravitational settling from the outer convective zone (OCZ) into the radiative core is viewed as the only solar modification of solar-nebula isotopic compositions to affect all elements. Evidence for gravitational settling is indirect, as observations are presently less precise than the predictions of <10‰ effects for the isotopes of solid-forming elements. Additional solar modification has occurred for light isotopes (D, Li, Be, B) due to nuclear destruction at the base of the convection zone, and due to production by nuclear reactions of photospheric materials with high-energy particles from the corona. Isotopic fractionation of long-term average samples of solar wind has been suggested by theory. There is some evidence, though not unambiguous, indicating that interstream (slow) wind is isotopically lighter than high-speed wind from coronal holes, consistent with Coulomb drag theories. The question of fractionation has not been clearly answered because the precision of spacecraft instruments is not sufficient to clearly demonstrate the predicted fractionations, which are <30‰ per amu between fast and slow wind for most elements. Analysis of solar-wind noble gases extracted from lunar and asteroidal soils, when compared with the terrestrial atmospheric composition, also suggests solar-wind fractionation consistent with Coulomb drag theories. Observations of solar and solar-wind compositions are reviewed for nearly all elements from hydrogen to iron, as well as the heavy noble gases. Other than Li and the noble gases, there is presently no evidence for differences among stable isotopes between terrestrial and solar photosphere compositions. Although spacecraft observations of solar-wind isotopes have added significantly to our knowledge within the past decade, more substantial breakthroughs are likely to be seen within the next several years with the return of long-exposure solar-wind samples from the Genesis mission, which should yield much higher precision measurements than in situ spacecraft instruments.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57313,
    title ="A new time-of-flight instrument for quantitative surface analysis",
    author = "Veryovkin, Igor V. and Calaway, Wallis F.",
    journal = "Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms",
    volume = "219",
    
    pages = "473-479",
    month = "June",
    year = "2004",
    doi = "10.1016/j.nimb.2004.01.105",
    issn = "0168-583X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150507-080757972",
    note = "© 2004 Elsevier B.V. Available online 19 February 2004. \n\nThis work was supported by the US Department of Energy, BES-Materials Sciences, under Contract W-31-109-ENG-38, and by NASA under Work Orders W-19,895 and W-10,091. The authors would like to thank Dr. Chun-Yen Chen for her participation in testing the SPIRIT instrument and measurements of many mass spectra including those shown in Fig. 3.",
    revision_no = "8",
    abstract = "A new generation of time-of-flight mass spectrometers that implement ion sputtering and laser desorption for probing solid samples and can operate in regimes of laser post-ionization secondary neutral mass spectrometry and secondary ion mass spectrometry is being developed at Argonne National Laboratory. These new instruments feature novel ion optical systems for efficient extraction of ions from large laser post-ionization volumes and for lossless transport of these ions to detectors. Another feature of this design is a new in-vacuum all-reflecting optical microscope with 0.5-μm resolution. Advanced ion and light optics and three ion sources, including a liquid metal ion gun (focusable to 50 nm) and a low energy ion gun, give rise to an instrument capable of quantitative analyses of samples for the most challenging applications, such as determining elemental concentrations in shallow implants at ultra-trace levels (for example, solar wind samples delivered by NASA Genesis mission) and analyzing individual sub-micrometer particles on a sample stage (such as, interstellar dust delivered by NASA Stardust mission). Construction of a prototype instrument has been completed and testing is underway. A more advanced instrument of similar design is under construction. The overall design of the new instrument and the innovations that make it unique are outlined. Results of the first tests to characterize its analytical capabilities are presented also.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/35535,
    title ="Quantifying the diffusion kinetics and spatial distributions of radiogenic ^4He in minerals containing proton-induced ^3He",
    author = "Shuster, David L. and Farley, Kenneth A.",
    journal = "Earth and Planetary Science Letters",
    volume = "217",
    number = "1-2",
    pages = "19-32",
    month = "January",
    year = "2004",
    
    issn = "0012-821X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20121119-100729426",
    note = "© 2003 Elsevier B.V. Received 25 April 2003; received in revised form 18 June 2003; accepted 7 October 2003. We thank T. Schneider, S. Mukhopadhyay and E. Schauble for helpful input, L. Hedges for sample preparation and E. Cascio for his expertise with the irradiation, and two anonymous reviewers. This work was supported by the National\nScience Foundation and by a N.S.F. Graduate Research Fellowship to D.L.S.[BW]",
    revision_no = "15",
    abstract = "Apatite, titanite and olivine samples were bombarded with a ~ 150 MeV proton beam to produce ~ 10^8 atoms/mg of spallation ^3He. High-precision stepped-heating experiments were then performed in which the artificial ^3He and, for apatite and titanite, the natural radiogenic ^4He were measured to characterize the diffusive behavior of each\nisotope. Helium-3 diffusion coefficients are in excellent agreement with concurrently and/or previously determined He\ndiffusion coefficients for each mineral. Our results indicate that proton-induced ^3He is uniformly distributed and that radiation damage associated with a proton fluence of ~ 5 x 10^(14) protons/cm^2 does not cause noticeable changes in ^4He diffusion behavior in at least apatite and titanite. Proton-induced ^3He can therefore be used to establish He diffusion coefficients in minerals with insufficient natural helium for analysis or those in which the natural ^4He distribution is inhomogeneous. In addition,step-heating ^4He/^3He analysis of a mineral with a uniform synthetic ^3He concentration provides a means by which a natural ^4He distribution can be determined. ",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57286,
    title ="On type B CAI formation: experimental constraints on fO_2 variations in spinel minor element partitioning and reequilibration effects",
    author = "Connolly, Harold C., Jr. and Burnett, D. S.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "67",
    number = "22",
    pages = "4429-4434",
    month = "November",
    year = "2003",
    doi = "10.1016/S0016-7037(03)00271-0 ",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-140725958",
    note = "© 2003 Elsevier Ltd.\n\nReceived July 2, 2002; accepted in revised form April 17, 2003.\n\nWe are grateful for helpful discussions with J. Beckett, G. MacPherson, A. Davis, and D. Mittelfeld. We thank A. El Groesy, an anonymous reviewer, and C. Koeberl for their helpful reviews that greatly improved the quality of this paper. This research was in part supported by NASA-NAG5-4319, D.S. Burnett P. I.",
    revision_no = "9",
    abstract = "We report data from a series of dynamic crystallization experiments that focus on determining the partition coefficients (D’s) for V and Ti in the spinel + liquid system of an average type B1 CAI bulk composition for three different fO_2 conditions. Partitioning data for Ca and Si are also obtained. We show that the D’s for V and Ti are fO_2 dependent with D_(Ti) decreasing at low oxygen fugacity due to the presence of Ti^(3+). D_V is essentially 0 in air, rises to 2.2 at the Fe-FeO buffer and drops to 1.4 at the C-CO buffer. This indicates that V^(3+) is highly compatible in spinel and that higher and lower valence states are much less compatible. We also report data from isothermal experiments that determine diffusion times for V and Ti in same system at a temperature close to the T_(max) for type B1 CAIs. Diffusion of these elements between spinel and liquid is surprisingly rapid, with essentially total equilibration of Ti and V between spinel and liquid in 90 h run duration. Lack of equilibration of Cr, Si, and Ca shows that the Ti and V equilibration mechanism was diffusion and not dissolution and reprecipitation. Our experimental run durations set an upper limit of a few tens of hours on the time that type B1 CAIs were at their maximum temperature. Based on our data we argue that subsolidus reequilibration between spinel inclusion and host-silicate phases within type B CAIs likely explains the observed range of V and Ti concentrations in spinels which are inclusions in clinopyroxene.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57317,
    title ="^4He/^3He thermochronometry",
    author = "Shuster, D. L. and Farley, K. A.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "67",
    number = "18",
    pages = "A436-A436",
    month = "September",
    year = "2003",
    doi = "10.1016/S0016-7037(03)00513-1",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150507-085549131",
    note = "© 2003 Elsevier B.V. ",
    revision_no = "15",
    abstract = "We demonstrate a technique that uses classical diffusion\ntheory to determine ^4He concentration profiles within\nminerals. This approach should prove useful for constraining\nthe low temperature cooling histories of individual samples\nand for correcting (U-Th)/He ages for partial diffusive loss. To validate the method, we investigated apatites with\nindependently constrained cooling histories. The minerals of\ninterest were irradiated with 220 MeV protons to induce an\nartificial distribution of spallation ^3He. Our results indicate that proton-induced ^3He is uniformly distributed and that radiation damage associated with a proton fluence of ~5x10^(14) protons/cm^2 does not cause noticeable changes in He diffusion behavior. Proton-induced ^3He can therefore be used to establish He diffusion coefficients in minerals with insufficient natural helium for analysis or those in which the natural ^4He distribution is  inhomogeneous. In addition, step heating ^4He/^3He analysis of a mineral with a uniform synthetic ^3He concentration provides a means to constrain its natural ^4He distribution that arose during ingrowth and diffusion over geologic time.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51641,
    title ="The petrogenesis of type B1 Ca-Al-rich inclusions: The spinel perspective",
    author = "Connolly, Harold C., Jr. and Burnett, D. S.",
    journal = "Meteoritics and Planetary Science",
    volume = "38",
    number = "2",
    pages = "197-224",
    month = "February",
    year = "2003",
    doi = "10.1111/j.1945-5100.2003.tb00260.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141112-101601652",
    note = "© 2003 The Meteoritical Society.\n\nReceived 12 February 2002; revision accepted 17 February 2003.\n\nWe thank J. R. Beckett for numerous\ndiscussions and helpful comments that vastly improved this\nmanuscript. We also thank A. El Goresy, S. Simon, L. Grossman, S. Russell, and G. MacPherson for helpful\ndiscussions. We are grateful to L. Grossman for the loan of\nAllende TS-34 and the Smithsonian for the loan of Leoville\n3537–-2. We thank A. Davis, H. Yurimoto, an anonymous\nreviewer, D. Mittlefehldt, and H. Nagahara for constructive\nand helpful comments. This research was funded by NASA\nNAG5–4319, D. S. Burnett PI and NASA NAG5–9789, K. D.\nMcKeegan PI. The UCLA ion microprobe facility is partially\nsupported by a grant from the NSF Instrumentation and\nFacilities program.",
    revision_no = "8",
    abstract = " Minor element variations in MgAl_2O_4 spinel from the type B1 calcium-aluminum-rich inclusion (CAI) Allende TS-34 confirm earlier studies in showing correlations between the minor element chemistry of spinels with their location within the inclusion and with the chemistry of host silicate phases. These correlations result from a combination of crystallization of a liquid produced by re-melting event(s) and local re-equilibration during subsolidus reheating. The correlation of the Ti and V in spinel inclusions with the Ti and V in the adjacent host clinopyroxene can be qualitatively explained by spinel and clinopyroxene crystallization prior to melilite, following a partial melting event. There are, however, difficulties in quantitative modeling of the observed trends, and it is easier to explain the Ti correlation in terms of complete re-equilibration. The correlation of V in spinel inclusions with that in the adjacent host clinopyroxene also cannot be quantitatively modeled by fractional crystallization of the liquid produced by re-melting, but it can be explained by partial re-equilibration. The distinct V and Ti concentrations in spinel inclusions in melilite from the edge regions of the CAI are best explained as being affected by only a minor degree of re-equilibration. The center melilites and included spinels formed during crystallization of the liquid produced by re-melting, while the edge melilites and included spinels are primary. The oxygen isotope compositions of TS-34 spinels are uniformly ^(16)O-rich, regardless of the host silicate phase or its location within the inclusion. Similar to other type B1 CAIs, clinopyroxene is ^(16)O-rich, but melilite is relatively ^(16)O-poor. These data require that the oxygen isotope exchange in TS-34 melilite occurred subsequent to the last re-melting event.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57296,
    title ="The Genesis Discovery Mission: Return of Solar Matter to Earth",
    author = "Burnett, D. S. and Barraclough, B. L.",
    journal = "Space Science Reviews",
    volume = "105",
    number = "3-4",
    pages = "509-534",
    month = "January",
    year = "2003",
    doi = "10.1023/A:1024425810605",
    issn = "0038-6308",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-152449868",
    note = "© 2003 Kluwer Academic Publishers.\n\nReceived 25 March 2002; Accepted in final form 26 August 2002.\n\nThe authors of this overview obviously only represent a small fraction of the skillful and dedicated technical staff from the Jet Propulsion Laboratory, Lockheed Martin Astronautics, Johnson Space Center, and Los Alamos National Laboratory who co-operated to make the Genesis mission a success. We gratefully acknowledge the support of this team. We also acknowledge the support and oversight provided by upper management at the Jet Propulsion Laboratory, Lockheed Martin Astronautics and NASA Headquarters.",
    revision_no = "12",
    abstract = "The Genesis Discovery mission will return samples of solar matter for analysis of isotopic and elemental compositions in terrestrial laboratories. This is accomplished by exposing ultra-pure materials to the solar wind at the L1 Lagrangian point and returning the materials to Earth. Solar wind collection will continue until April 2004 with Earth return in Sept. 2004. The general science objectives of Genesis are to ( 1) to obtain solar isotopic abundances to the level of precision required for the interpretation of planetary science data, ( 2) to significantly improve knowledge of solar elemental abundances, ( 3) to measure the composition of the different solar wind regimes, and ( 4) to provide a reservoir of solar matter to serve the needs of planetary science in the 21st century. The Genesis flight system is a sun-pointed spinner, consisting of a spacecraft deck and a sample return capsule ( SRC). The SRC houses a canister which contains the collector materials. The lid of the SRC and a cover to the canister were opened to begin solar wind collection on November 30, 2001. To obtain samples of O and N ions of higher fluence relative to background levels in the target materials, an electrostatic mirror ('concentrator') is used which focuses the incoming ions over a diameter of about 20 cm onto a 6 cm diameter set of target materials. Solar wind electron and ion monitors ( electrostatic analyzers) determine the solar wind regime present at the spacecraft and control the deployment of separate arrays of collector materials to provide the independent regime samples.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57349,
    title ="The Genesis Solar Wind Concentrator",
    author = "Nordholt, Jane E. and Wiens, Roger C.",
    journal = "Space Science Reviews",
    volume = "105",
    number = "3-4",
    pages = "561-599",
    month = "January",
    year = "2003",
    doi = "10.1023/A:1024422011514",
    issn = "0038-6308",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150507-150031683",
    note = "© 2003 Kluwer Academic Publishers.\n\nReceived 15 December 2001; Accepted in final form 21 May 2002.\n\nThe authors would like to acknowledge NASA contract number W-19,272 for supporting this work. The design, development, and construction of the Concentrator would not have been possible without the help of many individuals. The authors would like to thank the following outstanding individuals: Diane Albert, Frank Ameduri, Matt Anderson, Richard Bramlett, Randy Edwards, Brian Henneke, James Lake, and Stacy Rupiper of Los Alamos National Laboratory; Dennis\nGuerrero, Irene Arevalos, Greg Dirks, Jeff Roese, Toby Stecklein, Jack Taguiam, Syrrel Rogillio, and James Sanders of the Southwest Research Institute; Chet Sasaki, Virgil Mireles and Don Sevilla of the Jet Propulsion Laboratory; Lada Adamac of Caltech; Allen Dorn of Screen Technology Group; Jerry Spieckerman of Marketech, Inc.; Steve Good of Reynolds Industries, Inc.; Kenneth Bedard formerly of Precimeter, Inc.; and David King and Joseph Maciejewsky of Technology Assessment and Transfer, Inc., Wear Sciences Division.",
    revision_no = "13",
    abstract = "The primary goal of the Genesis Mission is to collect solar wind ions and, from their analysis, establish key isotopic ratios that will help constrain models of solar nebula formation and evolution. The ratios of primary interest include ^(17)O/^(16)O and ^(18)O/^(16)O to ±0.1%, ^(15)N/^(14)N to ±1%, and the Li, Be, and B elemental and isotopic abundances. The required accuracies in N and O ratios cannot be achieved without concentrating the solar wind and implanting it into low-background target materials that are returned to Earth for analysis. The Genesis Concentrator is designed to concentrate the heavy ion flux from the solar wind by an average factor of at least 20 and implant it into a target of ultra-pure, well-characterized materials. High-transparency grids held at high voltages are used near the aperture to reject >90% of the protons, avoiding damage to the target. Another set of grids and applied voltages are used to accelerate and focus the remaining ions to implant into the target. The design uses an energy-independent parabolic ion mirror to focus ions onto a 6.2 cm diameter target of materials selected to contain levels of O and other elements of interest established and documented to be below 10% of the levels expected from the concentrated solar wind. To optimize the concentration of the ions, voltages are constantly adjusted based on real-time solar wind speed and temperature measurements from the Genesis ion monitor. Construction of the Concentrator required new developments in ion optics; materials; and instrument testing and handling.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57278,
    title ="The Genesis Solar-Wind Collector Materials",
    author = "Jurewicz, A. J. G. and Burnett, D. S.",
    journal = "Space Science Reviews",
    volume = "105",
    number = "3-4",
    pages = "535-560",
    month = "January",
    year = "2003",
    doi = "10.1023/A:1024469927444",
    issn = "0038-6308",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-123712738",
    note = "© 2003 Kluwer Academic Publishers.\n\nReceived 30 January 2002; Accepted in final form 21 May 2002.\n\nA portion of this work was carried out through the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration Discovery Program. Special thanks to the commercial vendors who made singular efforts to meet the Genesis requirements, which were both stringent and unusual. Thanks also go to the members of the Genesis Engineering Teams, the JPL MicroDevices Laboratory Central Support Group, the Genesis Project Office, and to Alan Treiman who performed the initial diffusion-stability analysis. Two anonymous reviewers also helped to significantly clarify the content, and contributed their own humor to enhancing the project. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply endorsement by the United States Government, or the Jet Propulsion Laboratory, California Institute of Technology.",
    revision_no = "12",
    abstract = "Genesis (NASA Discovery Mission #5) is a sample return mission. Collectors comprised of ultra-high purity materials will be exposed to the solar wind and then returned to Earth for laboratory analysis. There is a suite of fifteen types of ultra-pure materials distributed among several locations. Most of the materials are mounted on deployable panels ('collector arrays'), with some as targets in the focal spot of an electrostatic minor (the 'concentrator'). Other materials are strategically placed on the spacecraft as additional targets of opportunity to maximize the area for solar-wind collection. Most of the collection area consists of hexagonal collectors in the arrays; approximately half are silicon, the rest are for solar-wind components not retained and/or not easily measured in silicon. There are a variety of materials both in collector arrays and elsewhere targeted for the analyses of specific solar-wind components. Engineering and science factors drove the selection process. Engineering required testing of physical properties such as the ability to withstand shaking on launch and thermal cycling during deployment. Science constraints included bulk purity, surface and interface cleanliness, retentiveness with respect to individual solar-wind components, and availability. A detailed report of material parameters planned as a resource for choosing materials for study will be published on a Genesis web site, and will be updated as additional information is obtained. Some material is already linked to the Genesis plasma data website (genesis.lanl.gov). Genesis should provide a reservoir of materials for allocation to the scientific community throughout the 21st Century.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57299,
    title ="Using proton-induced ^3He to study He diffusion kinetics and rock thermal histories",
    author = "Farley, K. A. and Shuster, D. L.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "66",
    number = "15A",
    pages = "A224",
    month = "August",
    year = "2002",
    doi = "10.1016/S0016-7037(02)01009-8",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-155302502",
    note = "© 2002 Published by Elsevier Ltd.",
    revision_no = "8",
    abstract = "We have investigated He release kinetics by step-heating\nof minerals in which we introduced artificial ^3He with a beam\nof ~150 MeV protons in a particle accelerator used primarily\nfor cancer therapy. This process mimics cosmic-ray spallation,\nand produces He with a ^3He/^4He ratio of about unity. The\ninduced helium is homogeneously distributed within the target\ncrystals, and because it is emitted with few MeV energies, the\n^3He should reside in sites indistinguishable from those of\nradiogenic ^4He.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51624,
    title ="Genesis Mission to Return Solar Wind Samples to Earth",
    author = "Wiens, Roger C. and Burnett, Donald S.",
    journal = "Eos",
    volume = "83",
    number = "21",
    pages = "229-234",
    month = "May",
    year = "2002",
    doi = "10.1029/2002EO000157",
    issn = "0096-3941",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141112-075941106",
    note = "© 2002 American Geophysical Union. \n\nWe thank the thousands of people who have contributed to this mission in so many different ways. This manuscript was supported by NASA contract number 19,272.",
    revision_no = "13",
    abstract = "The Genesis spacecraft, launched on 8 August 2001 from Cape Canaveral, Florida, will be the first spacecraft ever to return from interplanetary space. The fifth in NASAs line of low-cost, Discovery-class missions, its goal is to collect samples of solar wind and return them to Earth for detailed isotopic and elemental analysis. The spacecraft is to collect solar wind for over 2 years, while circling the L1 point 1.5 million km Sunward of the Earth, before heading back for a capsule-style re-entry in September 2004. After parachute deployments mid-air helicopter recovery will be used to avoid a hard landing. The mission has been in development over 10 years, and its cost, including development, mission operations, and initial sample analysis, is approximately $209 million.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51566,
    title ="Phosphate control on the thorium/uranium variations in ordinary chondrites: Improving solar system abundances",
    author = "Goreva, J. S. and Burnett, D. S.",
    journal = "Meteoritics and Planetary Science",
    volume = "36",
    number = "1",
    pages = "63-74",
    month = "January",
    year = "2001",
    doi = "10.1111/j.1945-5100.2001.tb01810.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141111-104435610",
    note = "© 2001 The Meteoritical Society\n\nReceived 2000 May 8; accepted in revised form 2000 September 20. \n\nThe authors are grateful to J. H. Jones and M. Ebihara for critical and constructive reviews of the manuscript. This work was supported by NASA grant NAG5-4319.",
    revision_no = "8",
    abstract = "Isotope dilution thorium and uranium analyses by inductively-coupled plasma mass spectrometry of 12 samples of Harleton (L6) show a much larger scatter than was previously observed in equilibrated ordinary chondrites. Th/U linearly correlates with 1/U in Harleton and in the total equilibrated ordinary chondrite data set as well. Such a correlation suggests a two component mixture and this trend can be quantitatively modeled as reflecting variations in the mixing ratio between two phosphate phases: chlorapatite and merrillite. The major effect is due to apatite variations, which strongly control the whole rock U concentrations. Phosphorous variations will tend to destroy the Th/U vs. 1/U correlation, and measured P concentrations on exactly the same samples as U and Th show a factor of 3 range. It appears that the P variations are compensated by inverse variations in U (a dilution effect) to preserve the Th/U vs. 1/U correlation. Because variations in whole rock Th/U are consequences of phosphate sampling, a weighted average of high accuracy Th/U measurements in equilibrated ordinary chondrites should converge to a significantly improved average solar system Th/U. Our best estimate of this ratio is 3.53 with σ_(mean) = 0.10.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57309,
    title ="Origin of Thorium/Uranium Variations in Carbonaceous Chondrites",
    author = "Goreva, J. S. and Burnett, D. S.",
    journal = "Meteoritics and Planetary Science",
    volume = "35",
    number = "S5",
    pages = "A61",
    month = "July",
    year = "2000",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150507-071022957",
    note = "© 2000 Meteoritical Society. Provided by the NASA Astrophysics Data System.",
    revision_no = "8",
    abstract = "Thorium-, U-, and Pb-isotopic analyses of a wide variety of planetary materials show that Th/U ratio (by weight) varies from 3.5 to 4.2. It is generally believed that chondritic meteorites contain refractory lithophile elements in a relative proportions close to solar, i.e., CI chondrites [1]. Surprisingly, a number of analyses of different types of carbonaceous chondrites show a large (at least a factor of 3) scatter in Th/U measurements [2]. The widest spread in Th/U is observed in the most primitive materials, CI-type\nchondrites. Cosmochronological models rely on the precise knowledge of the average solar system Th/U, therefore it is important to achieve a better understanding of the actinide chemistry in chondrites, e.g., what causes the variations in Th/U ratio.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51559,
    title ="Bids requested for Genesis Mission analytical facilities",
    author = "Burnett, Donald S.",
    journal = "Eos",
    volume = "81",
    number = "21",
    pages = "236",
    month = "May",
    year = "2000",
    doi = "10.1029/00EO00166",
    issn = "0096-3941",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141111-100203645",
    note = "© 2000 American Geophysical Union.",
    revision_no = "9",
    abstract = "The Genesis Discovery mission, to be launched in January 2001, will expose ultrapure materials to the solar wind for about 2 years and then return this sample to Earth for isotopic and chemical analysis in terrestrial laboratories.\n\nSample return missions use the best available instrumentation to achieve mission science goals. To complete the Genesis science objectives, advanced instrumentation that surpasses present laboratory sample analysis capabilities is required. Advanced Analytical Instrumentation Facilities (AAIFs) will be created for the mission to ensure that the best analytical instruments are used. This approach also enables broad participation by NASA scientists in solar wind sample return analysis.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57308,
    title ="On the Remelting of Type B Calcium-Aluminum-rich Inclusions",
    author = "Connolly, H. C., Jr. and Burnett, D. S.",
    journal = "Meteoritics and Planetary Science",
    volume = "35",
    number = "S5",
    pages = "A44-A45",
    month = "January",
    year = "2000",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150507-070242104",
    note = "© 2000 Meteoritical Society. Provided by the NASA Astrophysics Data System.",
    revision_no = "8",
    abstract = "We have shown [1-3] that the variation in the minor-element concentration of spinels (MgAI_20_4 and their relationship to host silicate chemistry from type B CAIs is a powerful tool in constraining the igneous history of these objects. We conducted electron microprobe studies of the minor-element distributions among spinels from three type Bl CAIs: Allende TS-34, Allende TS-23, and Leoville 3537-2. By maintaining the petrologic context (edge, middle, and center of the inclusion plus their host silicate phase), four populations of spinels are resolvable based on their positive TI to V correlation. Grains from the middle and center areas define trends that are divided into three populations: spinels enclosed by melilite, fassaite, and anorthite. These grains also show important TI, V, and Cr correlations with their host silicate chemistries. The other population resides within the edge area (mainly mantle\nmelilite) and is characterized by the highest V contents with little chemical relationship to their host silicates.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57310,
    title ="Release Profile as an Indicator of Solar Wind Neon Loss from Genesis Collectors",
    author = "Meshik, A. P. and Hohenberg, C. M.",
    journal = "Meteoritics and Planetary Science",
    volume = "35",
    number = "S5",
    pages = "A109",
    month = "January",
    year = "2000",
    
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150507-071746071",
    note = "© 2000 Meteoritical Society. Provided by the NASA Astrophysics Data System.\n\nThis work is supported by NASA grants #NAG9-l006 and #NAG5-4173.",
    revision_no = "9",
    abstract = "During the course of solar-wind-collector studies for the Genesis mission, we investigated retention of solar-wind Ne in Al deposited on sapphire (AloS). Temperature and lattice distortion effects caused by solar-wind H can affect the retention of light noble gases, but there is generally no way to identify that loss has occurred. We report here experimentally derived signatures that can characterize and identify such losses.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/52348,
    title ="A study of the minor element concentrations of spinels from two type B calcium-aluminum-rich inclusions: An investigation into potential formation conditions of calcium-aluminum-rich inclusions",
    author = "Connolly, Harold C., Jr. and Burnett, D. S.",
    journal = "Meteoritics and Planetary Science",
    volume = "34",
    number = "6",
    pages = "829-848",
    month = "November",
    year = "1999",
    doi = "10.1111/j.1945-5100.1999.tb01401.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141203-140511285",
    note = "© 1999 The Meteoritical Society.\n\nReceived 1998 May 29; accepted in revised form 1999 July 1. \n\nWe would like to thank G. J. MacPherson for the loan of\nUSNM Leoville 3537-2 and L. Grossman for the sample of Allende TS-23.\nThis project was greatly improved by numerous conversations with J. Paque,\nJ. Beckett, G. J. MacPherson, A. Davis, S. Russell, S. Simon, and\nL. Grossman, A. El Gorsey, R. Ash, and G. Rossman. We also thank D. Ebel\nand L. Grossman for data used in our condensation figure and P. Carpenter\nfor assistance with the microprobe analysis. The quality of this manuscript\nwas improved by constructive reviews from G. J. MacPherson, M. Ebihara,\nand associate editor J. S. Delaney, and we thank them. This project was\nsupported by NASA grant NAG5-4319, D. S. Burnett.",
    revision_no = "8",
    abstract = "We have conducted an electron microprobe study of minor element distributions among spinels from two type B1 calcium-aluminum-rich inclusions (CAIs): Allende TS-23 and Leoville 3537–2. We show that by maintaining the petrologic context (edge, middle, and center of the inclusion plus their host silicate phase), four populations of spinels are resolvable based on their minor element contents. One population resides within the edge area (mainly mantle melilite) and is characterized by the highest V contents. Unlike Leoville 3537–2, many edge grains from Allende TS-23 also have high-Fe contents (up to 4.0 wt%) and low-Cr values. Based on their V and Ti concentrations (which is positively correlated), middle and center grains define a trend that is divided into three populations: spinels enclosed by melilite, fassaite, and anorthite. The overall range in Ti concentration based on fractional crystallization should be much less than a factor of 2; however, the observed range is considerably larger. The minor element contents of these grains are interpreted as recording alteration, primary fractional crystallization, and a complex igneous history that may involve remelting and recrystallization. From our data, Allende TS-23 has experienced more alteration than Leoville 3537–2, which is consistent with previous petrologic studies of silicates within these objects; yet both objects have likely been remelted (at least one additional melting event, possibly two, postdating the initial formation of these CAIs). By invoking a remelting history, the large range ir Ti concentrations and the different populations of spinels can be explained. Although our data suggest that more than one generation of spinels exist within these objects, we are unable to establish any population of relic spinel grains that predate the initial melting event.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57292,
    title ="Apatite Control of Choncritic Actinide Chemistry?",
    author = "Goreva, J. S. and Burnett, D. S.",
    journal = "Meteoritics and Planetary Science",
    volume = "34",
    number = "S4",
    pages = "A45-A46",
    month = "July",
    year = "1999",
    doi = "10.1111/j.1945-5100.1999.tb01769.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-145122628",
    note = "© 1999 The Meteoritical Society.",
    revision_no = "7",
    abstract = "The solar system Th/U is regarded as about 3.7, and ratios close to this are directly measured in a wide variety of planetary materials. Consequently, given that chondritic composition is regarded as solar for refractory lithophile elements, it is surprising that some ordinary chondrites\nshow high ratios (6-6.5). We set out to understand the origin and implications of these anomalies, first by establishing that we had samples of the anomalous material using high accuracy isotope dilution, ICPMS measurements ofTh/U. Our three samples of Glatton (L6) were not anomalous\n(Th/U from 3.71 to 3.84), but for 12, typically gram-sized, samples of Harleton (L6) we find a range of Th/U from 2.5 to 6, a greater range of Th/U in one meteorite than in all previous ordinary chondrite analyses. Moreover, Fig. 1 shows (l) the Th/U variations linearly correlate with 11\nU, suggesting two component mixing; (2) other literature analyses follow the Harleton trend.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/52349,
    title ="The solar oxygen-isotopic composition: Predictions and implications for solar nebula processes",
    author = "Wiens, R. C. and Huss, G. R.",
    journal = "Meteoritics and Planetary Science",
    volume = "34",
    number = "1",
    pages = "99-107",
    month = "January",
    year = "1999",
    doi = "10.1111/j.1945-5100.1999.tb01735.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141203-141124907",
    note = "© 1999 The Meteoritical Society.\n\nReceived 1998 March 18; accepted in revised form 1998 November 5. \n\nThis work was partially supported by NASA grant\nNAGW-4182 and the Genesis Discovery mission. Helpful discussions and\ninformal and formal reviews by R. N. Clayton, K. Lodders, M. H. Thiemens,\nJ. T. Wasson, B-G. Choi, K. D. McKeegan, P. Bochsler, and P. Cassen are\ngreatly appreciated. We are also gratekl for editorial assistance by L. Schultz.",
    revision_no = "9",
    abstract = "The outer layers of the Sun are thought to preserve the average isotopic and chemical composition of the solar system. The solar O-isotopic composition is essentially unmeasured, though models based on variations in meteoritic materials yield several predictions. These predictions are reviewed and possible variations on these predictions are explored. In particular, the two-component mixing model of Clayton and Mayeda (1984) (slightly revised here) predicts solar compositions to lie along an extension of the calcium-aluminum-rich inclusion (CAI) ^(16)O line between (δ^(18)O, δ^(17)O) = (16.4, 11.4)%0 and (12.3, 7.5)%0. Consideration of data from ordinary chondrites suggests that the range of predicted solar composition should extend to slightly lower δ^(18)O values. The predicted solar composition is critically sensitive to the solid/gas ratio in the meteorite-forming region, which is often considered to be significantly enriched over solar composition. A factor of two solid/gas enrichment raises the predicted solar (δ^(18)O, δ^(17)O) values along an extension of the CAI ^(16)O line to (33, 28)%0. The model is also sensitive to the nebular O gas phase. If conversion of most of the gaseous O from CO to H_2O occurred at relatively low temperatures and was incomplete at the time of CM aqueous alteration, the predicted nebular gas composition (and hence the solar composition) would be isotopically heavier along a slope 1/2 line. The likelihood of having a single solid nebular O component is discussed. A distribution of initial solid compositions along the CAI ^(16)O line (rather than simply as an end-member) would not significantly change the predictions above in at least one scenario. Even considering these variations within the mixing model, the predicted range of solar compositions is distinct from that expected if the meteoritic variations are due to non-mass-dependent fractionation. Thus, a measurement of the solar O composition to a precision of several permil would clearly distinguish between these theories and should clarify a number of other important issues regarding solar system formation.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57290,
    title ="Recycling (?): Relict Spinels (?) in Type B Calcium-Aluminum-Rich Inclusions",
    author = "Connolly, H. C., Jr. and Burnett, D. S.",
    journal = "Meteoritics and Planetary Science",
    volume = "33",
    number = "S4",
    pages = "A34",
    month = "July",
    year = "1998",
    doi = "10.1111/j.1945-5100.1998.tb01327.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-144002469",
    note = "© 1988 The Meteoritical Society. ",
    revision_no = "8",
    abstract = "Type B calcium-aluminum-rich inclusions (CAIs) can be thought of as a type of chondrule despite obvious differences in size, composition, and texture. Nevertheless, igneous CAIs likely experienced similar thermal histories. A major constraint on the thermal history of chondrules is that they have been recycled, mainly supported by the presence relict grains. Although well known that igneous CAIs experienced at least two\nmelting events (counting Wark-Lovering rims), the identification of relict grains has been problematic.\nThe best candidate for relict grains within type B CAIs is spinel. Spinel is the liquidus phase with complete melting at approximately l50°C above type B peak melting temperatures (~1400°C). Consequently, relict spinels,\neither from a previous generation of CAIs or direct nebular condensate spinels, are stable at the inferred maximum heating temperature of type B CAIs. Minor- and trace-element concentrations can be used to distinguish relict grains from those that crystallized from an initially homogeneous liquid.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/39155,
    title ="SO_2-rock interaction on Io 2. Interaction with pure SO_2",
    author = "Burnett, D. S. and Goreva, Julia S.",
    journal = "Journal of Geophysical Research E",
    volume = "102",
    number = "E8",
    pages = "19371-19382",
    month = "August",
    year = "1997",
    
    issn = "0148-0227",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130701-100111471",
    note = "© 1997 by the American Geophysical Union.\nReceived July 8, 1996;   \nrevised February 25, 1997;\naccepted: 10 Mar. 1997;\n\n\nWe thank A. S. McEwen and an anonymous\nreviewer for thorough reviews. This research was supported by NASA NAGW 35-34 (D. Burnett) and NAGW 38-83 (S. Epstein). Caltech\ncontribution 5914.\n\n\n",
    revision_no = "11",
    abstract = "A Na-S mineral on the surface of Io is required to be the source of the famous atomic cloud. SO_2 is a confirmed atmospheric and surface constituent, and because of the rapid volcanic resurfacing rate, the SO_2 is buried within the crust, where at least occasionally, over many cycles of burial and eruption, it must contact silicate materials at midlevel crustal temperatures. Surface interaction experiments were performed for a wide variety of silicate compositions showing that interaction products of these with SO_2 could be observed at 1123 K on laboratory timescales, even in the absence of external redox agents. Not all experiments produced deposits that could be studied by scanning electron microscopy; some required the greater sensitivity of photoelectron spectroscopy (XPS). Characterization of the alteration products by XPS showed that both oxidized and reduced sulfur species were formed, indicating that a disproportionation mechanism producing a sulfate and a reduced S species although smaller amounts of interaction leading to Na_2SO_3 formation cannot be ruled out. The reduced sulfur species is best explained as elemental S which was independently documented for two compositions. Scanning electron microscopy studies for those compositions where reaction was extensive enough to be observed showed (1) Na_2SO_4 for a soda-lime composition, (2) a mixed Na-Ca-sulfate liquid and CaSO_4 for AbAnDi and a chondrule glass composition, and (3) Fe-sulfate for a natural obsidian. Infrared spectroscopy for the soda-lime glass composition showed peaks best explained by Na_2SO_4. We conclude that SO_2 disproportionation as well as direct formation from SO_3 under oxidizing conditions can produce Na_2SO_4 by interaction of SO_2 with silicates on Io, but Ca and Fe sulfates may form preferentially in more basaltic compositions. As highly oxidizing conditions may be unlikely for Io, the disproportionation mechanism may be more competitive on Io than it is in laboratory experiments. Very low rates of Na_2SO_4 production are required to supply the Io atomic cloud, so the interaction processes can be very inefficient.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57270,
    title ="Sputtering products of sodium sulfate: Implications for Io's surface and for sodium-bearing molecules in the Io torus",
    author = "Wiens, Roger C. and Burnett, D. S.",
    journal = "Icarus",
    volume = "128",
    number = "2",
    pages = "386-397",
    month = "August",
    year = "1997",
    doi = "10.1006/icar.1997.5758 ",
    issn = "0019-1035",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-102931550",
    note = "© 1997 Academic Press.\n\nReceived July 15, 1996; revised April 21, 1997.\n\nThe authors are grateful for numerous Io discussions with M. Brown, a helpful review from R. E. Johnson, unofficial reviews and/or advice from J. K. Wilson, A. Sprague, T. Johnson, T. A. Tombrello, and R. Baragiola, and initial experimental setup assistance from S. Coon. This work was supported by NASA Grants NAGW-3534 (D.S.B., R.C.W.) and NAGW-4182 (R.C.W., C.S.H.), and by the U.S. Department of Energy, BES-Materials Sciences, under Contract W-31-109-ENG-38.",
    revision_no = "11",
    abstract = "The composition of the sodium-bearing molecular ion cloud in the vicinity of Io may yield clues to Io's geochemistry. Likely Na-bearing source minerals are Na-sulfides and Na_2SO_4, with the relative composition depending on the distribution of thermal environments in the upper crust. These materials will be sputtered by co-rotating torus ions either from the surface or from atmospheric aerosols. Using laser postionization, we investigated the ion-sputtered neutral products of Na_2SO_4 to determine whether NaO in the Io torus might be a diagnostic indicator for sodium sulfate on Io's surface or in aerosols. With an ArF excimer laser (λ = 6.4 eV), single-photon saturation of the ionization step was achieved for NaS, Na_2O, and the combination Na_2S + Na_2O_2 at mass 78, while other species, including NaO, were close to saturation. Photofragmentation during the ionization step was minimal by all indications. The results predict sputtering ratios NaO/NaS > 8, Na_2O/NaS ∼8, Na_2/NaS ≥ 6, and Na/NaS ≥ 100. Multiphoton ionization was also attempted using a frequency-doubled (3.2-eV) Ti:sapphire femtosecond laser at high intensities, but saturation was not achieved for the major species, and there was evidence of photofragmentation.\nVelocity distributions of the sputter products show for the first time that significant fractions of sodium-bearing molecules can be sputtered into unbound trajectories from Io's surface, with escape fractions > 50% in the case of NaO. Combining relative sputter yields and velocity distributions gives escape ratios of NaO/NaS > 10, Na_2/NaS ∼ 6, and Na_2O/NaS ∼2.8 from Na_2SO_4. While absolute sputtering and escape ratios need to be compared for Na-sulfides versus Na_2SO_4, this work shows that, in the absence of significant modification by atmospheric chemical reactions, measurement of the neutral NaO/NaS ratio in the vicinity of Io could identify the major Na-bearing minerals.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/47239,
    title ="Europium valence state distributions in equilibrated ordinary chondrites",
    author = "Connolly, H. C., Jr. and Peters, M. T.",
    journal = "Meteoritics and Planetary Science",
    volume = "32",
    number = "S4",
    pages = "A30-A31",
    month = "July",
    year = "1997",
    doi = "10.1111/j.1945-5100.1997.tb01599.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20140715-152506716",
    note = "© 1997 The Meteoritical Society. Article first published online: 4 Feb 2010. Lunatic Asylum Contribution No. 970 (NASA NAGW-3297). Division Contribution No. 58241.",
    revision_no = "12",
    abstract = "It has been recognized for 30 years that the presence of Eu anomalies in REE patterns is due to the presence of divalent Eu, unique among the REE. However, it has not previously been possible to infer quantitative Eu^(+2)/Eu^(+3) ratios in natural samples. We have used ion probe data for lithophile trace elements for the phases in equilibrated ordinary chondrites [Guareiia (H6), Marion (L6) and St. Sevérin (LL6)] to perform mass-balance calculations that yield relatively precise Eu^(+2)/Eu^(+3) ratios.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57289,
    title ="The Stardust Mission: Returning Comet Samples to Earth",
    author = "Brownlee, D. E. and Tsou, P.",
    journal = "Meteoritics and Planetary Science",
    volume = "32",
    number = "S4",
    pages = "A22",
    month = "July",
    year = "1997",
    doi = "10.1111/j.1945-5100.1997.tb01599.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-142413492",
    note = "© 1997 The Meteoritical Society.\n\n",
    revision_no = "9",
    abstract = "Stardust is an approved NASA mission that will collect large numbers of cometary particles and return them to Earth for laboratory analysis. The collected samples will be processed at the Curatorial Facility at the NASA\nJohnson Space Center in Houston, Texas, where they will be allocated to investigators in a manner similar to the existing lunar sample, cosmic dust, and Antarctic meteorite programs. We urge all investigators interested in primitive materials to begin seriously considering what they would like to do with the samples when they are returned to Earth.\nStardust is the fourth mission in the new NASA Discovery program. It is highly focused on sample return and, following Discovery guidelines, is a low-cost, rapid-development project. The mission will launch in February\n1999, fly past Comet Wild 2 on January 1, 2004, and return samples to Earth on January 13, 2006. The spacecraft will collect particles by direct impact into low-density silica aerogel during a 6.1-km/s flyby approaching within 150 km of the nucleus. The particles, ranging in size up to >200 μm, will penetrate several hundred particle diameters into the aerogel, where they will remain until they are extracted in the curatorial facility. The best model of the comet dust production indicates that Stardust will collect more than 20,000particles>15 μmin diameter in its 1000 cm^2 area of collection surface.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57264,
    title ="Minor element partitioning and sector zoning in synthetic and meteoritic anorthite",
    author = "Steele, Ian M. and Peters, Mark T.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "61",
    number = "2",
    pages = "415-423",
    month = "January",
    year = "1997",
    doi = "10.1016/S0016-7037(96)00348-1",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-101839287",
    note = "© 1997 Elsevier Ltd.\n\nReceived April 17, 1996; accepted in revised form September 26, 1996.\n\nThis research was supported by grants to D. S. Burnett (NASA NAGW-1852) and I.M. Steele (NASA NAGW-3416, NSF EAR 93-03530, NSF EAR 93-16062). The authors appreciate the thoughtful reviews of both Dr. Bruce Watson of Rensselaer Polytechnic Institute and Dr. John Longhi of Yale University.",
    revision_no = "8",
    abstract = "Regular, geometric, apparently crystallographically-controlled, sector zoning has been produced in synthetic anorthite crystallized from a liquid of Type B Ca,Al-rich inclusion (CAI) composition. Cathodoluminescence (CL) provides a rapid method for observing the sectors. Sharp discontinuities in Mg concentration always accompany sharp changes in CL intensity at sector boundaries. Although CL intensity anti-correlates with Mg concentration, there is not a well-defined quantitative relationship, and Mg concentration steps range from as little as 5% to almost a factor of 2 for different CL boundaries. When measurable, Na also tends to anti-correlate with CL brightness in a given crystal and thus correlates with Mg. The partition coefficients for Mg and Na can vary by up to a factor of 2 depending on the particular sector and thus are not constant for CAI anorthite which formed by fractional crystallization. In contrast, Ti (either Ti^+3 or Ti^+4) concentration is not a function of sector zoning and thus does not affect the CL intensity.\n\nThe sector zoning and correlated chemical variations for synthetic anorthite are similar to those in natural anorthite from Type B CAIs. The CL intensity, boundary sharpness, and minor element zoning in synthetic anorthite are not affected by annealing at 850°C for three weeks. Overall, our observations suggest that the observed CL patterns and minor element zoning in Type B anorthite are igneous in origin and have not been modified by subsolidus reequilibration or alteration. This leads to the conclusion that the ^(26)Mg-^(26)Al systematics in CAIs (based almost entirely on anorthite) have not been modified by subsolidus reequilibration or alteration.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57316,
    title ="The Suess-Urey mission (return of solar matter to Earth)",
    author = "Rapp, Donald and Naderi, Firouz",
    journal = "Acta Astronautica",
    volume = "39",
    number = "1-4",
    pages = "229-238",
    month = "July",
    year = "1996",
    doi = "10.1016/S0094-5765(96)00140-3",
    issn = "0094-5765",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150507-084403376",
    note = "© 1997 Elsevier Science Ltd. Available online 18 February 1999.\n\nThe material in this report is not solely the work of the authors, but instead represents a summary of the efforts of the entire Suess-Urey Phase A team from JPL, Lockheed-Martin, Caltech, Los Alamos National Laboratory and NASA-JSC. We also acknowledge consultation provided by Bob Farquar and colleagues at Applied Physics Laboratory in support of the mission design.",
    revision_no = "15",
    abstract = "The Suess-Urey (S-U) mission has been proposed as a NASA Discovery mission to return samples of matter from the Sun to the Earth for isotopic and chemical analyses in terrestrial laboratories to provide a major improvement in our knowledge of the average chemical and isotopic composition of the solar system. The S-U spacecraft and sample return capsule will be placed in a halo orbit around the L1 Sun-Earth libration point for two years to collect solar wind ions which implant into large passive collectors made of ultra-pure materials. Constant Spacecraft-Sun-Earth geometries enable simple spin stabilized attitude control, simple passive thermal control, and a fixed medium gain antenna. Low data requirements and the safety of a Sun-pointed spinner, result in extremely low mission operations costs.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51349,
    title ="Competition between Na_2SO_4 and Na sulfide in the upper crust of Io",
    author = "Burnett, D. S.",
    journal = "Journal of Geophysical Research E",
    volume = "100",
    number = "E10",
    pages = "21265-21270",
    month = "October",
    year = "1995",
    doi = "10.1029/95JE01165",
    issn = "0148-0227",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141106-091042367",
    note = "Copyright 1995 by the American Geophysical Union. \n\n(Received November 9, 1994; revised April 3, 1995; accepted April 6, 1995.) \n\nPaper number 95JE01165. \n\nI gratefully acknowledge important thermodynamic discussions with John Beckett, and manuscript reviews by Fraser Fanale and Douglas Nash. This research was supported by Planetary Materials and Geochemistry grant NAGW 3534. Caltech contribution 5523.",
    revision_no = "8",
    abstract = "The Na atmosphere of Io requires a Na-S-O phase in the outer surface layers. Considering the various mechanisms for extraction of Na to the surface, the possible primary phases are Na_2O, Na_2S_x and Na_2SO_4. However, regardless of the primary phases brought to the surface, the shallow crustal recycling of material implied by the ongoing volcanism will tend to produce thermochemical equilibrium and cause all Na to end up as Na_2SO_4 or Na_2S_x. This hypothesis is investigated by relatively model-independent thermodynamic calculations. The major assumption is that material is statistically circulated to sufficiently high temperatures by burial that thermochemical equilibrium can be attained. For a wide range of assumed crustal (PT) conditions, Na_2O will be converted to Na_2SO_4. During residence in the shallowest crustal regions dominated by liquid SO_2, e.g., SO_2 geysers or fumaroles, or for any crustal regimes where SO_2 and S are in comparable abundances, Na-sulfides will be converted to Na_2SO_4. However, in high-temperature, low-pressure regimes with a low relative abundance of SO_2 relative to S (e.g., due to outgasing of SO_2), Na_2SO_4 is converted to Na sulfides. Such regimes could be relatively common on Io, e.g., associated with flows, lava lakes, or shallow intrusions. Consequently, because of thermochemical equilibration in different crustal environments, both Na_2SO_4 and Na sulfides will coexist on the Io surface.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57301,
    title ="Magnesium and titanium partitioning between anorthite and Type B CAI liquid: Dependence on oxygen fugacity and liquid composition",
    author = "Peters, Mark T. and Shaffer, Elizabeth E.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "59",
    number = "13",
    pages = "2785-2796",
    month = "July",
    year = "1995",
    doi = "10.1016/0016-7037(95)00173-W",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-161033659",
    note = "© 1995 Elsevier Ltd. \n\n(Received November 8, 1994; accepted in revised form April 4, 1995).\n\nWe would like to thank John Beckett, Marc Hirschmann, George Rossman, Ian Hutcheon, John Longhi, Ed Stolper, and David Live for valuable discussions and technical advice, and John Armstrong and Paul Carpenter for assistance with the electron microprobe. We would especially like to thank Henry Schreiber for providing us with Ti^(3+)-doped glasses as ESR standards. We would also like to thank Christian Koeberl, Gordon McKay, and Steve Simon for thorough reviews of the manuscript. This research was supported by NASA grant NAGW-1852 (Burnett).",
    revision_no = "9",
    abstract = "Experiments were conducted in air and at low oxygen fugacity (f_O_2)) to evaluate Mg and Ti partitioning between anorthite and liquid (D_(Mg) and D_(Ti) in a synthetic composition similar to that of a Type B Ca, AI-rich inclusion (CAI). The starting material showed a range of compositions, which allowed assessment of the composition dependence of D_(Mg) and D_(Ti) in this system. Additional experiments using a homogeneous split of the same material investigated the effect of oxygen fugacity on the partitioning of Ti^(3+) and Ti^(4+) between anorthite and liquid. The low foe charges were purple, consistent with the presence of significant amounts of Ti^(3+).This was verified by electron spin resonance (ESR) spectra, and quantitative estimates of Ti^(3+) contents were obtained using ESR. The Ti and Mg partition coefficients in the air run using the homogeneous starting material are similar (0.034 and 0.036, respectively) and consistent with those determined in other studies. However, D_(Ti) at low f_(O_2) is slightly greater than D_(Ti) in the air experiments. Using Ti^(3+)/total Ti from the ESR measurements, D_(Ti^(3+)) is calculated to be about 0.040. \n\nThe range of compositions reveal a clustering of D_(Mg) and D_(Ti) within charges, but a wide range of D_s between charges of different composition. A well-defined inverse correlation exists between D_(Mg) and D_(Ti). This variation is not due to temperature-dependence, but is instead due to the dependence of D_(Mg) and D_(Ti) on liquid composition (Si and Al in particular). D_(Mg) correlates positively with Si content and negatively with Al content, while D_(Ti) shows the opposite correlations. \n\nThe results of these experiments have interesting implications for the petrogenesis of Type B CAIs and for substitution mechanisms of Mg, Ti^(4+), and Ti^(3+) into anorthite. Crystallization models for Type B CAIs permit certain predictions concerning trace element systematics in plagioclase. The Mg and Ti systematics are best explained by a fractional crystallization model where plagioclase crystallizes very late (>95% crystallization), and D_(Ti^(3+)). is equal to D_(Ti^(4+)). The results from our experiments support this model for the relative partitioning of Ti^(4+) and Ti^(3+) between plagioclase and liquid. In addition, the dependence of D_(Mg), and D_(Ti) on the Si content of a Type B CAI liquid helps explain systematics expected during late-stage crystallization of plagioclase. The composition dependence of D_(Mg) and D_(Ti) also allows assessment of substitution mechanisms in anorthite using a crystallization reaction approach. Using these methods, a plausible mechanism for Mg involves substitution for tetrahedral A1 by the reaction Mg^(2+) + Si^(4+) = 2AI^(3+), consistent with that proposed by previous workers. The systematics are also consistent with Ti^(4+) and Ti^(3+) substitution for tetrahedral Si^(4+) by the reactions 2Al^(3+) + Ti^(4+) = Ca^(2+) + 2Si^(4+) and Al^(3+) + Ti^(3+) = Ca^(2+) + Si^(4+), respectively.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/5261,
    title ="Simultaneous dual-element analyses of refractory metals in naturally occurring matrices using resonance ionization of sputtered atoms",
    author = "Calaway, W. F. and Wiens, R. C.",
    journal = "Journal of Vacuum Science and Technology A",
    volume = "13",
    number = "3",
    pages = "1310-1315",
    month = "May",
    year = "1995",
    
    issn = "0734-2101",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:CALjvsta95",
    note = "©1995 American Vacuum Society \n\n(Received 21 October 1994; accepted 25 January 1995) \n\nThe authors thank Paul Carpenter and John Armstrong for their assistance with the SEM and electron probe analyses. Joel Blum is thanked for providing the Ni-Os-Re standard and George Rossman for the laurite sample. This work was supported by the U.S. Department of Energy, BES-Materials Sciences, under Contract No. W-31-109-ENG-38 (ANL) and by NASA Grant No. NAGW 3592 (Caltech).",
    revision_no = "8",
    abstract = "The combination of secondary neutral mass spectrometry (SNMS) and resonance ionization spectroscopy (RIS) has been shown to be a powerful tool for the detection of low levels of elemental impurities in solids. Drawbacks of the technique have been the laser-repetition-rate-limited, low duty cycle of the analysis and the fact that RIS schemes are limited to determinations of a single element. These problems have been addressed as part of an ongoing program to explore the usefulness of RIS/SNMS instruments for the analysis of naturally occurring samples. Efficient two-color, two-photon (1+1) resonance ionization schemes were identified for Mo and for four platinum-group elements (Ru, Os, Ir, and Re). Careful selection of the ionization schemes allowed Mo or Ru to be measured simultaneously with Re, Os, or Ir, using two tunable dye lasers and an XeCl excimer laser. Resonance frequencies could be switched easily under computer control, so that all five elements can be rapidly analyzed. In situ measurements of these elements in metal grains from five meteorites were conducted. From the analyses, estimates of the precision and the detection limit of the instrument were made. The trade-off between lower detection limits and rapid multielement RIS analyses is discussed.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57315,
    title ="Leonard Medal Citation for Robert M. Walker",
    author = "Burnett, Don",
    journal = "Meteoritics and Planetary Science",
    volume = "29",
    number = "4",
    pages = "343-435",
    month = "July",
    year = "1994",
    doi = "10.1111/j.1945-5100.1994.tb00614.x",
    issn = "1086-9379",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150507-083819473",
    note = "© 1994 The Meteoritical Society.",
    revision_no = "7",
    abstract = "The 1993 Leonard Medalist, Robert M. Walker, started his\nprofessional career during the 1950s, as a physicist studying radiation effects in solids. The work for which he is probably best known, the study of particle tracks in solids, began in the early 1960s at the General Electric Research Laboratories, in collaboration with R. L. Fleischer and P. B. Price. Many of us working in the field of meteoritics have had no formal training in geology. This is usually a handicap, but it proved to be important in launching the science of trackology. Muscovite mica was an\nimportant material in the early studies of particle tracks and, even today, is the optimum track detector in many respects.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57007,
    title ="Experimental studies of trace element partitioning in Ca, Al-rich compositions: Anorthite and perovskite",
    author = "Simon, S. B. and Kuehner, S. M.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "58",
    number = "5",
    pages = "1507-1523",
    month = "March",
    year = "1994",
    doi = "10.1016/0016-7037(94)90553-3",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-112242771",
    note = "© 1994 Elsevier Science Ltd. Received 12 March 1993, Accepted 5 November 1993, Available online 3 April 2003.\n\nWe were aided by reviews from A. El Goresy and two anonymous reviewers. This research was supported by NASA grants NAG 9-54 and NAGW-3340 (Grossman), NAG 9-l11 and NAGW-3384 (Davis), NAG 9-94 and NAGW-1852 (Burnett) and NAG 9-5 1 and NAGW-3345 (R. N. Clayton).\n\nEditorial handling: C. Koeberl",
    revision_no = "10",
    abstract = "Using electron probe and ion probe techniques, experimental crystal-liquid partition coefficients (D) have been measured in meteoritic Ca,Al-rich inclusion (CAI) compositions for Mg, Zr, Y, and REEs in anorthite and perovskite. Partitioning data for Ti in anorthite and Al in perovskite are also reported. Where cross-comparisons are possible between electron and ion probe data, agreement is good. Concentration variations in anorthite for many elements are beyond what can be explained by fractional crystallization, but show well-defined interelement correlations which could reflect the temperature dependence of the D values or could result from liquid boundary layers. For anorthite our D values for REEs are lower, and they decrease more rapidly with decreasing ionic radius than most in the literature. Most of the older REE D patterns for plagioclase in the literature are too flat because of insufficient purity of mineral separates or because of analytical problems. New ion probe data for minor and trace elements in anorthite from type B CAIs permit detailed comparisons with fractional crystallization models based on the measured D values. For most comparisons, models and observations do not agree for amounts of crystallization less than 90%. It is possible that anorthite does not appear until after 95% crystallization, compared to about 40% which would be expected from isothermal equilibrium crystallization experiments. The LREEs are highly compatible elements in perovskite, but D values drop sharply for the HREEs, Y, and Zr. D values for REEs increase strongly from air to highly reducing conditions as coupled REE-Ti^(+3) substitutions become possible. Model calculations show that REE patterns in igneous perovskites from CAIs will reflect the D pattern, and the models can explain some REE patterns from compact type A CAIs. However, there are other sets of trace element data for perovskite in CAIs that cannot easily be explained by igneous processes.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51382,
    title ="SO_2-rock interaction on Io: Reaction under highly oxidizing conditions",
    author = "Johnson, M. L. and Burnett, D. S.",
    journal = "Journal of Geophysical Research E",
    volume = "98",
    number = "E1",
    pages = "1223-1230",
    month = "January",
    year = "1993",
    doi = "10.1029/92JE02509",
    issn = "0148-0227",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141106-133834261",
    note = "Copyright 1993 by the American Geophysical Union. \n\n(Received November 14, 1991; revised October 7, 1992; accepted October 8, 1992.) \n\nPaper number 92JE02509. \n\nThis manuscript was greatly improved by reviews from D. Nash and an anonymous reviewer as well as useful comments by C. Chapman. This research was supported by NASA Planetary Materials and Geochemistry grant NAG 9-94.",
    revision_no = "9",
    abstract = "Laboratory simulations have been carried out to test the possibility that interactions of SO_2 and silicates can produce Na-S compounds which can account for the observed surface enrichment of Na relative to Si on Io. A wide variety of silicate compositions were heated under oxidizing conditions with a SO_2/O_2 = 1 gas phase at a mid-level crustal temperature for Io (1123K). All experiments produced sulfate deposits on the silicate surfaces. The nature of the sulfate changed systematically with the silicate Ca/Na ratio, with mixtures of CaSO_4 and Na-rich sulfate formed by basaltic compositions having higher Ca/Na but only alkali-rich sulfates formed for more granitic (low Ca/Na) compositions. For crystalline albite and an albite-orthoclase eutectic glass composition, K and Al-rich sulfates were formed. Assuming that burial of SO_2 to the temperatures of our experiments is plausible on Io and that somewhat less oxidizing conditions do not qualitatively change the results, SO_2-rock interactions producing Na-rich sulfates could account for the Io surface enrichment in Na. Observations on minor elements, such as K or Ca, in the atomic cloud or in magnetospheric ion spectra could be used to identify sulfates as Io surface phases and, conceivably, even define Ionian crustal magma types. Many analyses show significant S excesses which are best interpreted as due to the presence of bisulfate (HSO_4.) components, and NaHSO_4 deserves consideration as an Io surface mineral. The possibility of elemental S on Io can be regarded as a totally separate issue from the problem of the surface Na enrichment.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56992,
    title ="Experimental determination of U and Th partitioning between clinopyroxene and natural and synthetic basaltic liquid",
    author = "La Tourrette, T. Z. and Burnett, D. S.",
    journal = "Earth and Planetary Science Letters",
    volume = "110",
    number = "1-4",
    pages = "227-244",
    month = "May",
    year = "1992",
    doi = "10.1016/0012-821X(92)90050-6",
    issn = "0012-821X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-085539852",
    note = "© 1992 Elsevier Science Publishers B.V. Received 8 October 1991, Accepted 28 February 1992, Available online 23 October 2002.\n\nWe thank H. Nagasawa and D. Stakes for providing the basalt samples. Neutron irradiations were carried out by P. Rogers at the TRIGA reactor facility. C. Irvine and P. Carpenter assisted with the electron microprobe analyses. Discussions\nwith M. Baker, J. Beckett, D. Bell, I. Carmichael, M. Johnson, G. Mattioli, G. Rossman and E. Stolper were very helpful. Critical reviews by C. Lesher and B. Mysen resulted in considerable improvements in the manuscript.\nThis research was supported by a NASA Graduate Student Researchers Program Fellowship.",
    revision_no = "10",
    abstract = "Clinopyroxene-silicate liquid partition coefficients for U and Th have been determined by particle track radiography from 1 atm crystallization experiments at controlled fO_2. Two natural basaltic and one synthetic composition were studied at fO_2 values from the Ni—NiO oxygen buffer to 1 log unit more oxidizing than Fe—FeO (IW+ 1). Over the range of fO_2 values and compositions studied, D_U^(cpx/liq) = 0.0034–0.015,D_(Th)^(cpx/liq) = 0.008–0.036, and D_(Th)/D_U= 3.4–1.1. With decreasing fO_2, D_(Th)/D_U can decrease by up to a factor of 3 for a given composition, primarily from an increase in D_U^(cpx/liq), which we interpret as resulting from an increase in the proportion of tetravalent U in the system with decreasing fO_2. This demonstrates that crystal-liquid U—Th fractionation is fO_2 dependent and that U in terrestrial magmas is not entirely tetravalent. D_(Th)^(cpx/liq) appears to decrease in the two basalts at the lowest fO_2, possibly as a result of changes in composition with fO_2.\n\nOur data show the sense of U—Th fractionation by clinopyroxene-liquid partitioning is consistent with previous experimental determinations, in that D_(Th)^(cpx)/D_U^(cpx)> 1 in all cases. This indicates that, during partial melting, the liquid will have a Th/U ratio less than the clinopyroxene in the source. The observed ^(238)—U^(230)Th disequilibrium in MORB requires that the partial melt should have a Th/U ratio greater than the bulk source, and, therefore, cannot result from clinopyroxene-liquid partitioning. Further, the magnitudes of the measured partition coefficients are too small to generate significant U—Th fractionation in either direction. Assuming that clinopyroxene contains the bulk of the U and Th in MORB source, our results indicate that ^(238)U—^(230)Th disequilibrium in MORB may not be caused by partial melting at all.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57312,
    title ="The status of PIXE in geochemistry",
    author = "Burnett, D. S. and Woolum, D. S.",
    journal = "Abstracts of Papers of the American Chemical Society",
    volume = "202",
    number = "2",
    pages = "NUCL-77",
    month = "August",
    year = "1991",
    
    
    issn = "0065-7727",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150507-075612971",
    note = "© 1991 American Chemical Society.",
    revision_no = "9",
    abstract = "PIXE is only one of several in-situ microanalytical techniques available to geochemists, but it occupies a unique niche in terms of a combination of accuracy and sensitivity. PIXE is 1-2 orders of magnitude more sensitive than electron probe analysis and has comparable accuracy at present. In the future, the simpler PIXE X-ray production physics could allow an order of magnitude greater accuracy for major element analysis. Secondary ion mass spectrometry has greater sensitivity, but, although progress has recently been made, SIMS has no general scheme for correcting for matrix effects on ion yields. In contrast, the conversion of observed x-ray counts to concentrations for PIXE is based on well understood physics. Synchrotron X-ray fluorescence has comparable accuracy and perhaps slightly better sensitivity than PIXE, but has much worse depth resolution. The excellent signal to noise inherent in PIXE could be fully realized with the use of efficient crystal spectrometers instead o the Si(Li) detectors utilized in essentially all studies to date.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56999,
    title ="Response to Comment by W.A. Myers and P.K. Kuroda on “Actinide abundances in ordinary chondrites”",
    author = "Hagee, B. and Bernatowicz, T. J.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "55",
    number = "8",
    pages = "2359-2363",
    month = "August",
    year = "1991",
    doi = "10.1016/0016-7037(91)90111-H",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-101514364",
    note = "© 1991 Pergamon Press plc. Received 7 April 1991, Accepted 14 May 1991.",
    revision_no = "9",
    abstract = "One aspect of our recent paper (HAGEE et al., 1990) on\nactinide abundances in ordinary chondrites is estimation of\nthe amount of ^(244)Pu present in these meteorites at the time of their formation. This estimate is based on the quantity of ^(244)Pu spontaneous fission Xe, a component whose resolution from other Xe components present must be based on observed isotopic compositions in the meteorite and assumed compositions for the contributing components. In their comments, MYERS and KURODA (1991) advocate a different approach to component analysis of Xe than the one we used and arrive at correspondingly different estimates of fission Xe and ^(244)Pu abundances.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51516,
    title ="Solar-wind krypton and solid/gas fractionation in the Early Solar Nebula",
    author = "Wiens, Roger C. and Burnett, D. S.",
    journal = "Geophysical Research Letters",
    volume = "18",
    number = "2",
    pages = "207-210",
    month = "February",
    year = "1991",
    doi = "10.1029/91GL00213",
    issn = "0094-8276",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141110-123753242",
    note = "Copyright 1991 by the American Geophysical Union. \n\n(Received August 17, 1990; revised November 19, 1990; accepted November 21, 1990) \n\nPaper number 91GL00213. \n\nThis research was supported in part by NASA grants NAG 9-94 to D. Burnett and NAG 9-60 to R. O. Pepin. J. Kerridge and an anonymous reviewer are thanked for their assistance, and profitable discussions with D. Stevenson are acknowledged.",
    revision_no = "9",
    abstract = "Krypton is the best candidate for determining limits on solid/gas fractionation in the early sun because of the smoothness of the odd-mass abundance curve in its mass region, which permits relatively precise interpolations of its abundance assuming no fractionation. Here we calculate the solar-system Kr abundance from solar-wind noble-gas ratios, determined previously by low-temperature oxidations of lunar ilmenite grains, normalized to Si by spacecraft solar-wind measurements. The estimated ^(83)Kr abundance of 4.1 ± 1.5 per 10^6 Si atoms is within uncertainty of estimates assuming no fractionation, determined from CI-chondrite abundances of surrounding elements. This is significant because it is the first such constraint on solid/gas fractionation, though the large uncertainty only confines it to somewhat less than a factor of two.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56995,
    title ="Uranium and minor-element partitioning in Fe-Ti oxides and zircon from partially melted granodiorite, Crater Lake, Oregon",
    author = "La Tourrette, T. Z. and Burnett, D. S.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "55",
    number = "2",
    pages = "457-469",
    month = "February",
    year = "1991",
    doi = "doi:10.1016/0016-7037(91)90004-O",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-094750631",
    note = "© 1991 Pergamon Press.\n\nReceived February 26, 1990; Accepted in revised form November 21, 1990.\n\nP. Carpenter and J. Armstrong assisted with the electron microprobe analyses. Neutron irradiations were carried out by T. Crofoot at the TRIGA reactor facility at U. C. Irvine. Reviews by M. Harrison, P. Henderson, M. Clynne, T. Sisson, and an anonymous reviewer and helpful discussions with S. Newman, G. Rossman, and L. Silver are greatly appreciated. This study was initiated while CRB was a visiting professor at Caltech.",
    revision_no = "9",
    abstract = "Crystal-liquid partitioning in Fe-Ti oxides and zircon was studied in partially melted granodiorite blocks ejected during the climactic eruption of Mt. Mazama (Crater Lake), Oregon. The blocks, which contain up to 33% rhyolite glass (75 wt% SiO_2), are interpreted to be portions of the magma chamber walls that were torn off during eruption. The glass is clear and well homogenized for all measured elements except Zr. Results for Fe-Ti oxides give DU^(oxide/liq) ≈ 0.1. Partitioning of Mg, Mn, Al, Si, V, and Cr in Fe-Ti oxides indicates that grains surrounded by glass are moderately well equilibrated with the melt for many of the minor elements, while those that are inclusions in relict plagioclase are not. Uranium and ytterbium inhomogeneities in zircons indicate that the zircons have only partially equilibrated with the melt and that uranium appears to have been diffusing out of the zircons faster than the zircons were dissolving. Minimum U, Y, and P concentrations in zircons give maximum DU^(zrc/liq) = 13,DY^(zrc/liq) = 23, and DP^(zrc/liq) = 1, but these are considerably lower than reported by other workers for U and Y. Based on our measurements and given their low abundances in most rocks, Fe-Ti oxides probably do not play a major role in U-Th fractionation during partial melting. The partial melts were undersaturated with zircon and apatite, but both phases are present in our samples. This demonstrates an actual case of non-equilibrium source retention of accessory phases, which in general could be an important trace-element fractionation mechanism. Our results do not support the hypothesis that liquid structure is the dominant factor controlling trace-element partitioning in high-silica rhyolites. Rough calculations based on Zr gradients in the glass indicate that the samples could have been partially molten for 800 to 8000 years.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57014,
    title ="Relict grains in CAls, revisited",
    author = "Burnett, D. S. and Johnson, M. L.",
    journal = "Meteoritics",
    volume = "25",
    number = "4",
    pages = "353",
    month = "December",
    year = "1990",
    
    issn = "0026-1114",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-125809922",
    note = "© 1990 Meteoritical Society. Provided by the NASA Astrophysics Data System.",
    revision_no = "7",
    abstract = "Although the Type B CAI are clearly igneous rocks, they were probably not completely molten (1, 2), thus the possibility exists that preexisting materials can be recognized and characterized. Relict phases were proposed to explain high U and Th concentrations in both melilite\nand fassaite which would require unreasonably high  partition coefficients (D} if due to crystal-liquid partitioning (3). More detailed study showed very rare perovskite grains and enigmatic Ti hot spots in melilite\n(4). Kuehner et al. (5) subsequently reported very high lithophile trace element contents, including actinides, for fassaite inclusions in melilite which they proposed as relict phases, but Simon et al. (6) show that the fassaite inclusions can be better explained as being the last drops of liquid crystallization. In any case, the original observations and interpretations of (3) still point to an actinide-rich relict host phase. To be able to say what levels of Ti, U, and Th in melilite can be explained by igneous partitioning, we have measured D(mel) for these\nelements in a synthetic CAI composition under controlled fD_2 conditions, extended down to nebular conditions by carrying out experiments in graphite crucibles in pure CO. Actinide partition coefficients are quite low: D(Th} = 0.008 and D(U) = 0.0007 (possibly a record low in measured\nD values). The D for trivalent U should be around 0.1-0.3 depending on Ak content as the ionic radius of U^(+3) is similar to La. Thus, for solar nebula fD_2's and CAI compositions less than 1 % of the U is trivalent. The measured D prove that igneous partitioning fails to explain\nthe average U contents of type B CAI melilites, the  difference being a factor of 600. D(Ti) is 0.018 at Ak23 and increases with Ak content. D(Ti) is relatively similar in air and at solar nebula fD_2s, surprising given the documented importance of trivalent Ti. In any case, the measured D(Ti) show that melilite Ti levels around 200-300 ppm in early crystallizing melilite can be explained by igneous partitioning, but higher levels would be indicative of resorbed Ti-rich relict phases (e.g., perovskite). To make a closer comparison ofU and Ti in CAI melilites, the fission track images of (3) have been quantitatively mapped at 20 microns resolution for two mm-sized rim and one mantle melilite. High resolution quantitative U distribution data on adjacent fassaites were also obtained. One rim grain shows several U-rich fassaites like those of(5), but the other melilites do not. There are broad U-rich regions in all grains which will be characterized in more detail. The mantle grain is especially rich in detail, but some of this may be correlated with secondary alteration. There is rough correlation ofU content and Ti in the rim grains, but the scale of the Ti analyses, based on electron probe points, is much smaller than that for U. If relict phases, e.g., perovskite, dominate the actinide distributions, they might also affect other lithophile\ntrace elements, e.g., REE. References: (1) Wark D. (1983) thesis. (2) Stolper E. and Paque J. (1986) Geochim., Cosmochim. SO, 2159. (3) Murrell M. and Burnett D. (1987) Geochim. Cosmochim. SI, 985. (4) Johnson M., Burnett D. and Woolum D. (1988) Meteoritics 23, 276. (5) Kuehner S., Davis A. and Grossman L. (1989) Geophys. Res. Lett. 16, 775. (6) Simon S., Davis A. and Grossman L. (1990) LPSC 21, 1161.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56996,
    title ="Actinide abundances in ordinary chondrites",
    author = "Hagee, B. and Bernatowicz, T. J.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "54",
    number = "10",
    pages = "2847-2858",
    month = "October",
    year = "1990",
    doi = "10.1016/0016-7037(90)90019-H",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-095816014",
    note = "© 1990 Pergamon Press. Received 14 August 1989, Accepted 17 July 1990. \n\nWe thank E. Olsen, G. J. Wasserburg, C. Moore, R. Hutchison, and P. Pellas for meteorite samples. The manuscript was improved by thorough reviews from G. Crozaz, U. Ott, P. Pellas, and an anonymous reviewer. This research was supported by NASA grants T-783-H (USGS), NAG 9-94 (Caltech), and NSF grant EAR-8709445 (Washington U.). \n\nEditor handling: H. Palme.",
    revision_no = "9",
    abstract = "Measurements of ^(244)Pu fission Xe, U, Th, and light REE (LREE) abundances, along with modal petrographic determinations of phosphate abundances, were carried out on equilibrated ordinary chondrites in order to define better the solar system Pu abundance and to determine the degree of variation of actinide and LREE abundances. Our data permit comparison of the directly measured Pu/U ratio with that determined indirectly as (Pu/Nd) × (Nd/U) assuming that Pu behaves chemically as a LREE. Except for Guareña, and perhaps H chondrites in general, Pu concentrations are similar to that determined previously for St. Séverin, although less precise because of higher trapped Xe contents. Trapped ^(130Xe)/_(136Xe) ratios appear to vary from meteorite to meteorite, but, relative to AVCC, all are similar in the sense of having less of the interstellar heavy Xe found in carbonaceous chondrite acid residues. The Pu/U and Pu/Nd ratios are consistent with previous data for St. Séverin, but both tend to be slightly higher than those inferred from previous data on Angra dos Reis. Although significant variations exist, the distribution of our Th/U ratios, along with other precise isotope dilution data for ordinary chondrites, is rather symmetric about the CI chondrite value; however, actinide/(LREE) ratios are systematically lower than the CI value. Variations in actinide or LREE absolute and relative abundances are interpreted as reflecting differences in the proportions and/or compositions of more primitive components (chondrules and CAI materials?) incorporated into different regions of the ordinary chondrite parent bodies. The observed variations of Th/U, Nd/U, or Ce/U suggest that measurements of Pu/U on any single equilibrated ordinary chondrite specimen, such as St. Séverin, should statistically be within ±20–30% of the average solar system value, although it is also clear that anomalous samples exist.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51517,
    title ="Igneous origin for the Na in the cloud of Io",
    author = "Johnson, Mary L. and Burnett, D. S.",
    journal = "Geophysical Research Letters",
    volume = "17",
    number = "7",
    pages = "981-984",
    month = "June",
    year = "1990",
    doi = "10.1029/GL017i007p00981",
    issn = "0094-8276",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141110-130314699",
    note = "Copyright 1990 by the American Geophysical Union. \n\n(Received December 29, 1989; revised March 6, 1990; accepted March 9, 1990.) \n\nPaper number 90GL00748. \n\nWe thank Jeffery Warner (Chevron Research Lab) for aid in SEM analysis and John Pirolo and Gabor Faludi for glass working. Mary Johnson thanks Mark Parisi, as usual. This research was supported by NASA NAGW-1741.",
    revision_no = "8",
    abstract = "We heated mixtures of sulfur and Na-bearing silicates in evacuated silica glass capsules to temperatures between 600°C and 950°C. At or above 850°C, Na-silicate glass reacts with elemental S to form a (Na,K) sulfide. Mobilization of this phase may account for the presence of Na and K on the surface of Io, and hence in the material sputtered into the Jovian magnetosphere.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57006,
    title ="The interpretation of solar system abundances at the N = 50 neutron shell",
    author = "Burnett, D. S. and Woolum, D. S.",
    journal = "Astronomy and Astrophysics",
    volume = "228",
    number = "1",
    pages = "253-259",
    month = "February",
    year = "1990",
    
    issn = "0004-6361",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-110936591",
    note = "© 1990 European Southern Observatory. Provided by the NASA Astrophysics Data System. Received November 29, 1988; accepted June 27, 1989. \n\nWe acknowledge a helpful review of this manuscript by F. Kappeler. Support for this work was from NASA grants NAG 9-94 (DSB) and NAG 9-57 (DSW).",
    revision_no = "8",
    abstract = "New data on CI chondrite abundances demonstrate a high degree of smoothness for the A= 75-100 mass range for odd\nA nuclei, except for a single element peak at Y ascribable to the s-process peak for the N = 50 neutron shell. Literature estimates of s-process abundances, N., permit a smooth N. curve to be drawn; however the resultant \"non-s\" abundance curve (nominally r-process) does not show a peak analogous to peaks associated with the N = 82 or 126 shells. However, both the nominal N. and \"non-s\" abundance curves show similar rapid increases below mass 70. It is more reasonable to ascribe the \"non-s\" rise as an artifact from relatively small differences in the N. and total\nabundances, indicating that a relatively broad r-process peak is indeed present. The solar system even A abundances in this mass region are not smooth but show a saw-tooth structure which is also reflected in neutron capture cross sections, indicating that the saw-tooth is an s-process feature. The r-only even A nuclei define the r-process peak assuming that it is smooth. Assuming the systematics of the r-process even and odd A abundance peaks at the N = 82 and 126 shells apply to N = 50, the odd A r-process peak for N = 50 can be obtained, which in turn permits a new calculation of N. for odd A. The new N, is relatively smooth, but, contrary to expectations, the product of N. and the neutron capture cross section is not a smooth function of A, but contains structure, especially a rise between masses 82-84, which is not compatible with an exponential distribution of neutron exposures.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56977,
    title ="Determination of trace element mineral/liquid partition coefficients in melilite and diopside by ion and electron microprobe techniques",
    author = "Kuehner, S. M. and Laughlin, J. R.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "53",
    number = "12",
    pages = "3115-3130",
    month = "December",
    year = "1989",
    doi = "10.1016/0016-7037(89)90093-8",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150424-150904750",
    note = "© 1989 Pergamon Press. \n\nReceived 6 February 1989, Accepted 15 September 1989. \n\nWe are grateful to I. M. Steele and A. M. Davis for guidance in the operation of the electron and ion microprobes, respectively, and also for their discussions of our results. We thank John Beckett for the melilite starting materials and for helpful discussions, and Astrid Howard for help with synthesis experiments. We profited from discussions with E. Stolper and from reviews by R. Hervig, N. Shim& and D. Lindstrom. This work was supported by funds from the National Aeronautics and Space Administration through grants NAG 9-54 (to L. Grossman), NAG 9-94 (to D. S. Burnett), and NAG 9-5 1 (to R. N. Clayton).",
    revision_no = "10",
    abstract = "The use of the ion microprobe for quantitative analysis of Sr, Y, Zr, La, Sm, and Yb in melilite and pyroxene is evaluated. Three trace element-doped synthetic glasses of composition Ak_40, Ak_80, and Di_2AbAn were analyzed by ion microprobe (IMP) using ion yields determined from Corning glass standards. IMP-determined oxide concentrations in the Di_2AbAn glass agree well with electron microprobe (EMP) analyses (to within 6%), but IMP analyses of the melilite glasses deviate from EMP averages by up to 19%. The deviations are due to erroneous SiO_2 estimates caused by suppression of Si ion intensities by the enhanced concentrations of Ca and Al in the melilite glasses compared to the standards. Thus, in order to determine compositions of melilite, diopside, and glass from subliquidus experiments on each of the three starting compositions, we adopted a new set of ion yields such that IMP analyses of the three starting glasses reproduce the EMP average compositions. Further IMP and EMP comparisons of the subliquidus assemblages show that quantitative analyses of melilite, diopside, and glass can be obtained by IMP that are within 10% of the concentrations obtained by EMP, when ion yields determined from glass starting compositions are used. EMP-IMP comparison of crystal and glass analyses also suggests that a structural matrix effect may result in overestimation of SrO (10–12%) in melilite by IMP.\n\nComparison of our data for Ak_12 and Ak_90 melilite compositions with literature results shows that melilite/liquid for REE^3+ determined by IMP decrease with increasing X_Ak (Ak_90: D_La = 0.038, D_Sm = 0.032, D_Yb = 0.0086; Ak: 0.67, 0.75, 0.25, respectively) while that for Sr (=Eu^2+) changes only slightly (0.99 to 0.78, respectively). Since X_Ak increases with decreasing temperature for all melilite with X_Ak<0.7, a progressively larger positive Eu anomaly is predicted for melilite as it crystallizes with falling temperature. Our diopside/liquid data are characterized by a large degree of scatter on most interelement correlation plots of apparent partition coefficients. The data cannot be understood in terms of simple models of boundary layer formation but require a complex surface partitioning explanation. Nevertheless, estimates of diopside/liquid are in excellent agreement with literature data.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57003,
    title ="A test of the smoothness of the elemental abundances of carbonaceous chondrites",
    author = "Burnett, D. S. and Woolum, D. S.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "53",
    number = "2",
    pages = "471-481",
    month = "February",
    year = "1989",
    doi = "10.1016/0016-7037(89)90398-0",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-104719362",
    note = "© 1989 Pergamon Press plc. Received 20 May 1988, Accepted 14 November 1988.\n\nWe acknowledge valuable assistance with software installation at CalTech by S. Spicklemeyer and with accelerator operation by M. Hollander and J. Tesmer. The manuscript was improved by reviews from E. Anders and J. Morgan. We thank R. Clarke for the meteorite samples. Support was by NASA grants NAG 9-94 (Burnett) and NAG 9-57 (Woolum). \n\nEditorial handling: S. R. Taylor",
    revision_no = "9",
    abstract = "The identification of CI chondrite concentrations with average solar system abundances for heavy elements is based primarily on the smoothness of the CI abundance curves for odd mass nuclei. A good test of smoothness is measurement of all elements in a given mass range in the same sample with the same technique. High precision proton-induced X-ray spectra of CI chondrites yielded analyses of 17 elements (Ni through Ru, plus Fe and Pb) with precisions better than 10% for all except As, Pb, Nb, and Ru. Excellent theoretical descriptions of the spectra were obtained. Two independent estimates of precision agree well, giving confidence in the quoted errors. Intersample differences are the largest source of variability. Within these limits good agreement with literature results are obtained, except for As and Y. Although our Y values are 10 to 30% lower than previously adopted, amonoelemental s-process peak in the abundance curve at Y is still necessary. Except for Br (higher by 59% in Ivuna), there are no significant concentration differences between Orgueil and Ivuna. In general, our results confirm previous abundance curves. The abundances are exceptionally smooth and strongly decreasing in the mass 60–75 region. From mass 75–101 a smooth curve can be drawn, within limits of intersample variability, except for the Y peak. Over the whole periodic table a large number of peaks of probable nucleosynthetic origin can be identified, some understood, some not. These smoothness deviations are 10 to 30% and set an overall limit to the smoothness argument alone in justifying using CI abundances as average solar system values.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57280,
    title ="High precision thick target PIXE analyses of carbonaceous meteorites",
    author = "Burnett, D. S. and Woolum, D. S.",
    journal = "Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms",
    volume = "35",
    number = "1",
    pages = "67-74",
    month = "November",
    year = "1988",
    doi = "10.1016/0168-583X(88)90099-7",
    issn = "0168-583X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-125511624",
    note = "© 1988 Elsevier Science Publishers B.V. Received 2 May 1988, Revised 14 July 1988. \n\nWe acknowledge valuable assistance with software installation at Ca!Tech by S. Spicklemeyer and with accelerator operation by M. Hollander and J. Tesmer. Support was by NASA grants NAG 9-94 (Burnett) and NAG 9-57 (Woolum).",
    revision_no = "10",
    abstract = "High precision proton-induced X-ray (PIXE) thick target spectra of carbonaceous meteorites have been deconvoluted using previously described programs. Even in cases of totally overlapping peaks excellent fits to spectra were obtained. Concentrations for 15 elements in the mass range 56–100, as well as Pb, agree well in most cases with previous literature values. The total concentration range studied was over 105, with the lowest concentrations precisely analyzed being around 1 ppm.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57288,
    title ="Interpretation of Solar System Abundances Around the N = 50 Neutron Shell",
    author = "Woolum, D. S. and Burnett, D. S.",
    journal = "Meteoritics",
    volume = "23",
    number = "9",
    pages = "312-312",
    month = "September",
    year = "1988",
    
    issn = "0026-1114",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-141705171",
    note = "© 1988 Meteoritical Society. Provided by the NASA Astrophysics Data System.",
    revision_no = "9",
    abstract = "New measurements [l] of CI chondrites for Ni-Ru show a high degree\nof smoothness of the odd-A solar system abundance curve (SSAC) through\nthe region of the N = 50 closed neutron shell. The resolved s- and\nr-process peaks at the N = 82 and 126 neutron shells [2] are not apparent\nfor the N = 50 region. Our data confirm the necessity for a single element\n89Y SSAC peak, presumably of s-process origin. If the total SSAC is\nsmooth but made of contributions from more than one nucleosynthesis\nprocess, then at least the major contributing processes must also have\nsmooth abundance curves. Within errors, a smooths-process abundance\n(N,) curve can be drawn using N, from Beer and co-workers. For A=\n75-85 there are strong \"non-s\" contributions which could be flat or\nshow a shallow maximum at mass 79-81. (N-N,; suppressed scale). This\nmaximum would be analogous to the \"r-process\" peaks at A = 129 or\n195. The reason that the two-peak structure for N = 50 is not apparent\nin the total abundance curve is that the lower mass peak is relatively\nbroad, leading to unresolved sand non-speaks in the total SSAC. The\nrise in the N-N, curve below mass 75 is probably an error in the theoretical\nN,, so the \"non-s\" peak is better defined than at first glance.\nBelow mass 69 it is hard to separate the contributions of n-capture\nnucleosynthesis from the high-mass tail of the iron group nuclei, the\norigin of which is not well understood.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57287,
    title ="Relict Refractory Element Rich Phases in Type B CAI",
    author = "Johnson, M. L. and Burnett, D. S.",
    journal = "Meteoritics",
    volume = "23",
    number = "9",
    pages = "276-276",
    month = "September",
    year = "1988",
    
    issn = "0026-1114",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-140738836",
    note = "© 1988 Meteoritical Society. Provided by the NASA Astrophysics Data System.",
    revision_no = "9",
    abstract = "Of the possible processes involved in Type B CAI history, igneous processes are the most tractable for study. Temperature and time scales inferred are commensurate with feasible laboratory simulations. We have previously reported melilite (mel) crystal liquid partition coefficients, Di, for Sm, Yb, Sr (Eu^(++) analog), and Y (Ho analog). Our data for akermanite (Ak) 30 mel compositions is in good agreement with literature data where direct/extrapolated comparisons are possible. Even allowing for significant variations in Di with progressive crystallization, comparisons of predictions for the initial (0-30%) fractional crystallization of mel with our Sr, Y contents obtained for mel cores in Allende Type B CAI, with comparable Ak contents, indicate that the natural data substantially exceed (factors of 1.5-2.5 x) those\npredicted. Similar results are obtained for Y, Zr in fassaite (fass) based on estimates of the Di from literature data. In this case, excesses of these trace elements are up to factors of about x 5. Thus, while the trace elements observed in natural CAI (Sr in mel and Y, Zr in fass) are in qualitative agreement with igneous partitioning, the trace element abundances are higher than quantitative predictions.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57284,
    title ="^(244)Pu Abundance in Ordinary Chondrites",
    author = "Hagee, B. and Bernatowicz, T. J.",
    journal = "Meteoritics",
    volume = "23",
    number = "9",
    pages = "271-272",
    month = "September",
    year = "1988",
    
    issn = "0026-1114",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-132722417",
    note = "© 1988 Meteoritical Society. Provided by the NASA Astrophysics Data System.",
    revision_no = "11",
    abstract = "The cosmic abundance of ^(244)Pu is an important parameter in models of nucleosynthetic chronology and as a reference value in studies of solar system chronology. Experimental determination of this abundance is a long-standing problem which has still not been fully solved. Two different approaches have been used, both based on measuring ^(244)Pu\nvia its fission product Xe, but in two different classes of meteoritic material. One class consists of samples relatively rich in Pu and relatively poor in Xe components, especially trapped Xe, which interfere with identification offission Xe. Such materials, e.g., achondrites, phosphates,\nrefractory inclusions, are, however, chemically  fractionated, and lacking a stable or long-lived isotope of Pu the ^(244)Pu measurements must be translated to cosmic abundance by assuming geochemical coherence with another element, typically Nd. By this approach the best estimate\n(1) of cosmic ^(244)Pu abundance, stated relative to co-produced (r-process) ^(238)U, is ^(244)Pu/^(238)U = 0.004. The other class of material is bulk chondrite,\nbelieved to be an unbiased sampling of non-volatile elements. We believe that this is the best approach to determining the cosmic abundance of ^(244)Pu, since assessing whether Pu is geochemically coherent with Nd\nor another element requires independent knowledge of the unfractionated abundance of ^(244)Pu. The whole-rock chondrite approach is experimentally difficult, however. For some time the best estimate of ^(244)Pu abundance by this approach was ^(244)Pu/^(238)U = 0.0l5, based on an analysis of the LL6 chondrite St. Severin (2). More extensive and sophisticated analyses of St. Severin (3, 4) led to an improved estimate ^(244)Pu/^(238)U = 0.007, sharply lower than the previous value but still substantially higher than the value based on differentiated samples. While it is important to determine ^(244)Pu abundances in whole-rock chondrites other than the single meteorite St. Severin, previously available data on other meteorites have not been usefully precise. We have determined fission Xe concentrations (Table) by stepwise heating analysis ofa group of(unirradiated) ordinary chondrites selected to facilitate identification of fission Xe. Isotope dilution measurements of U, Th, Nd and Ce on aliquots of the samples used for gas analysis are under\nway. These samples were prepared from alternating cut slabs; the remaining slab faces have been examined for general petrological characterization and for distribution of phosphates, the principal hosts of Pu. The data available so far indicate fission Xe concentrations and\n^(244)Pu/^(238)U ratios consistent with those in St. Severin. The fission Xe calculations require assumption of trapped Xe composition and are sensitive to this assumption. The tabulated fission concentrations are minima in that they assume trapped ^(130)Xe/^(136)Xe equal to the highest observed value. The trapped ^(130)Xe/^(136)Xe ratios for all these meteorites are similar and, as previously noted for St. Severin (4), are significantly different (higher) from AVCC.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57279,
    title ="Melilite Crystal/Liquid Partitioning of Refractory Lithophiles",
    author = "Woolum, D. S. and Burnett, D. S.",
    journal = "Meteoritics",
    volume = "22",
    number = "4",
    pages = "534-535",
    month = "December",
    year = "1987",
    
    issn = "0026-1114",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-124345915",
    note = "© 1987 Meteoritical Society. Provided by the NASA Astrophysics Data System.",
    revision_no = "7",
    abstract = "The trace element chemistry of CAi's is complicated because of their multistage histories (e.g., Grossman, 1980; Murrell and Burnett, 1987). There is more to CAI origin than just igneous processes, even for Type B inclusions. We have initiated in-situ trace element microdistribution studies of synthetic and natural samples, to determine\nwhich aspects of CAI trace element microdistributions are due to igneous processes. Our ultimate goal is to assess those aspects that are not explicable in terms of igneous\nprocesses, so as to place constraints on the additional processes involved.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56967,
    title ="Actinide chemistry in Allende Ca-Al-rich inclusions",
    author = "Murrell, M. T. and Burnett, D. S.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "51",
    number = "4",
    pages = "985-999",
    month = "April",
    year = "1987",
    doi = "10.1016/0016-7037(87)90110-4",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150424-142143052",
    note = "© 1987 Pergamon Journals Ltd. Received 17 June 1986, Revised 19 January 1987, Available online 14 April 2003.\n\nWe wish to thank both L. Grossman for generously providing us with a sample of TS23F1 and G. MacPherson for 3529-41. We are grateful for the excellent cooperation of the LBL 88-in. cyclotron staff, in particular Ruth Mary Larimer. We thank A. Hashimoto for discussions and J. Beckett and D. Wark for detailed critical comments on this manuscript. This research was supported by NASA grant NAG 9 94. Editorial handling: H. Y. McSween. Jr. \n\n Caltech Division of Geological and Planetary Sciences Contribution Number 4322",
    revision_no = "9",
    abstract = "The microscale distribution of U and Th has been studied by fission track radiography in a set of Ca-Al-rich inclusions from the Allende meteorite. In the Type B inclusions, generally believed to have been melted, the major phases melilite and fassaite are important actinide host phases with similar Th/U and roughly three times higher concentrations in melilite than fassaite. Significant enrichments are also found on grain boundaries and in some regions of alteration. The distribution is not completely understood in terms of igneous partitioning and may also reflect incomplete assimilation of relict materials during melting. On the rims of Type B inclusions and throughout all other inclusions studied, perovskite is the dominant actinide host phase. However, perovskite does not have a characteristic Th/U value; measured ratios range from 1.4 to 12, both above and below the accepted solar system value of 3.8. Overall, neither alteration nor loss or gain of an actinide-rich phase appears to have been an important Th/U fractionation mechanism; volatility differences may be the dominant factor. Some results, e.g., high Th/U for “fluffy” Type A inclusions, can be interpreted as resulting from incomplete incorporation of the more volatile U during a primary condensation stage, but more complex interpretations are required for inclusions with low Th/U. The Th/U and REE abundance patterns for the spinel plus perovskite rim suggest derivation of this rim by volatilization of interior material. The time scale for this heating is required to be brief (<10^4 sec), but within this constraint spinel-perovskite rim formation by several mechanisms (deceleration heating, passage through nebular hot spots, differential sublimation or vaporization plus recondensation) is possible.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57002,
    title ="Experimental geochemistry of Pu and Sm and the thermodynamics of trace element partitioning",
    author = "Jones, John H. and Burnett, Donald S.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "51",
    number = "4",
    pages = "769-782",
    month = "April",
    year = "1987",
    doi = "10.1016/0016-7037(87)90091-3",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-103522711",
    note = "© 1987 Pergamon Press Ltd. Received 7 May 1986, Accepted 24 December 1986.\n\nWe thank C. Lesher and R. Nielsen for constructive reviews. T. Benjamin provided advice and assistance during the experimental portion of this study. This work was supported by NASA grants NSG 7202 and NAG 9-39 and NSF grant EAR76-84402.\nEditorial handling: E. B. Watson.",
    revision_no = "8",
    abstract = "The partitioning of Pu and Sm between diopside/liquid and whitlockite/liquid has been investigated experimentally to evaluate the geochemical coherence of Pu and the light REEs. ^(Pu)D/^(Sm)D is 2 ~ for both diopsidic pyroxene and whitlockite. This small amount of fractionation would be decreased further if Pu were compared to Ce or Nd. Our experimental results thus validate the suggestion that Pu behaves as a LREE during igneous processes in reducing environments. Our data and the data of Ray et al. (1983) indicate that temperature rather than melt composition is the most important control on elemental partitioning. This is true even though we demonstrate that additions of only 1–2 wt.% of P2_O_5 to the diopside-anorthite-albite system change ^(Pu)D_(cpx) by a factor of two. Our data suggest that P_2O_5 in aluminosilicate melts serves as a complexing agent for the actinides and lanthanides.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57311,
    title ="Trace element contents of primitive meteorites; A test of solar system abundance smoothness",
    author = "Woolum, D. S. and Burnett, D. S.",
    journal = "Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms",
    volume = "22",
    number = "1-3",
    pages = "376-379",
    month = "March",
    year = "1987",
    doi = "10.1016/0168-583X(87)90362-4",
    issn = "0168-583X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150507-072439341",
    note = "© 1987 Elsevier Science Publishers B.V.\n",
    revision_no = "9",
    abstract = "Elemental abundances from Cl carbonaceous chondrite meteorites are thought to represent the average solar system (“cosmic”) composition, based on the agreement between Cl and solar photospheric abundances and on the smoothness of heavy element abundances of odd mass nuclei when plotted as a function of mass number. To test Cl elemental smoothness, we have analyzed Cl meteorites, using conventional PIXE (proton probe) techniques, where we have good sensitivity for the range of elements: Ni to Mo. Preliminary analyses indicate that elemental smoothness is only approximate, with possible deviations of 30% to perhaps even 50%. This may be due to chemical fractionation. Alternatively, explanations for nonsmooth behavior may be understandable with the aid of general ideas of n-capture nucleosynthesis. As Cl abundances are refined, it could be that the lack of elemental smoothness may provide the strongest argument for the identification of Cl with primordial solar system abundances.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57273,
    title ="A Test of Solar-System Abundance Smoothness",
    author = "Woolum, D. S. and Burnett, D. S.",
    journal = "Meteoritics",
    volume = "21",
    number = "4",
    pages = "543-544",
    month = "December",
    year = "1986",
    
    issn = "0026-1114",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-105708306",
    note = "© 1986 Meteoritical Society.",
    revision_no = "12",
    abstract = "Carbonaceous chondrite (C1) elemental abundances are thought to represent the average\nsolar system (\"cosmic\") composition (see e.g. Anders and Ebihara, 1982) based on the\nagreement between C1 and photospheric abundances and on the smoothness of heavy\nelement abundances of odd mass nuclei when plotted as a function of mass number (A).\nThe latter argument presently determines the accuracy of the identification.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56970,
    title ="Silica-bearing chondrules and clasts in ordinary chondrites",
    author = "Brigham, C. A. and Yabuki, H.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "50",
    number = "8",
    pages = "1655-1666",
    month = "August",
    year = "1986",
    doi = "10.1016/0016-7037(86)90128-6",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150424-145049610",
    note = "© 1986 Pergamon Journals Ltd. Received 11 April 1985, Accepted 6 May 1986, Available online 31 March 2003.\n\nThe Sharps and Bremervörde samples used in this study were obtained with the cooperation of the U.S. National Museum. We thank D. Lal for the Dhajala specimen. We have benefitted from comments on the manuscript by W. Cassidy, J. Grossman, B. Mason, E. Olsen, and A. Rubin. The Caltech portion of this work was supported by NSF Grant EAR 83-08290.\n\nEditorial handling: H. Y. McSween, Jr.",
    revision_no = "10",
    abstract = "Unusual silica-bearing chondrules and clasts have been observed in several unequilibrated ordinary chondrites. There appear to be two distinct types: (I) silica, low-Ca pyroxene assemblages, and (II) silica, fayalite intergrowths coexisting with low-Ca pyroxene. Only the former types are chondrules. The bulk compositions of most of these objects can be expressed in terms of three components—MgO, FeO, and SiO_2—since Ca, Al, and Na are essentially trace elements. Secondary alteration has probably perturbed the Fe/Mg ratios in most objects and produced Ca-rich pyroxenes in some type II clasts, but the silica, low-Ca pyroxene and fayalite are hard to understand as other than primary phases. Such silica-rich bulk compositions can be understood as an intermediate temperature condensate of a solar gas, formed by the loss of refractory solid material by gas-solid separation before the complete condensation of silicon. Alternatively, the silicarich bulk compositions could have been formed by extreme reduction of normal chondritic olivine and orthopyroxene; however, the observed Ca, Al depletion and the lack of Ni-poor metals are not explained by this model. The fayalite-bearing clasts can be explained by a relatively complex two-stage process involving reduction followed by oxidation. Partial reduction of olivine in the presence of S produces Mg-rich pyroxene, silica, and FeFeS; oxidation of metal and sulfide followed by reaction with silica forms fayalite. An alternative is that the fayalite-bearing clasts result from the decomposition of ferrosilite, but this requires the production of metastable ferrosilite during shock or some other high-pressure event. The simplest unflawed alternative is that the fayalite-bearing clasts result from the mixing of a partially molten silica, fayalite liquid with Mg-rich pyroxene.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51384,
    title ="Partitioning of K, U, and Th between sulfide and silicate liquids: Implications for radioactive heating of planetary cores",
    author = "Murrell, M. T. and Burnett, D. S.",
    journal = "Journal of Geophysical Research B",
    volume = "91",
    number = "B8",
    pages = "8126-8136",
    month = "July",
    year = "1986",
    doi = "10.1029/JB091iB08p08126",
    issn = "0148-0227",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141106-134700232",
    note = "Copyright 1986 by the American Geophysical Union. \n\n(Received June 10, 1985; revised February 3, 1986; accepted February 13, 1986) \n\nPaper number 5B5677. \n\nWe thank J. Warner and Chevron Oil Field Research, La Habra, California, for access to their electron probe for the light element analyses. We also thank E. Stolper for the use of the piston-cylinder apparatus. We are especially grateful to Gerry Fine for his excellent help with the piston-cylinder runs and to W.R. Heuser for assistance with some of the early experiments. This work was supported by NASA grant NAG 9-94. Caltech Division of Geological and Planetary Sciences contribution number 4230.",
    revision_no = "8",
    abstract = "The possibility of heating of planetary cores by K radioactivity has been extensively discussed, as well as the possibility that K partitioning into the terrestrial core is the reason for the difference between the terrestrial and chondritic K/U. We had previously suggested that U and Th partitioning into FeFeS liquids was more important than K. Laboratory FeFeS liquid, silicate liquid partition coefficient measurements (D) for K, U, and Th were made to test this suggestion. For a basaltic liquid at 1450°C and 1.5 GPa, D_U is 0.013 and D_K is 0.0026; thus U partitioning into FeFeS liquids is 5 times greater than K partitioning under these conditions. There are problems with 1-atm experiments in that they do not appear to equilibrate or reverse. However, measurable U and Th partitioning into sulfide was nearly always observed, but K partitioning was normally not observed (D_K ≲ 10^(−4)). A typical value for D_U from a granitic silicate liquid at one atmosphere, 1150°C, and low f0_2 is about 0.02; D_(Th) is similar. At low f0_2 and higher temperature, experiments with basaltic liquids produce strong Ca and U partitioning into the sulfide liquid with D_U > 1. D_(Th) is less strongly affected. Because of the consistently low D_K/D_U, pressure effects near the core-mantle boundary would need to increase D_U by factors of ∼10^3 with much smaller increases in DU in order to have the terrestrial K and U abundances at chondritic levels. In addition, if radioactive heating is important for planetary cores, U and Th will be more important than K unless the lower mantle has K/U greater than 10 times chondritic or large changes in partition coefficients with conditions reverse the relative importance of K versus U and Th from our measurements.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57283,
    title ="Another Look at Actinide Chemistry in Ca-Al-Rich Inclusions",
    author = "Murrell, M. T. and Burnett, D. S.",
    journal = "Meteoritics",
    volume = "20",
    number = "4",
    pages = "713-714",
    month = "December",
    year = "1985",
    
    issn = "0026-1114",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-132202541",
    note = "© 1985 Meteoritical Society.",
    revision_no = "10",
    abstract = "Th/U values for Allende inclusions are often high relative to the accepted solar system\naverage (3.8). In order to understand this fractionation, we are using fission track radiography\nto measure Th and U distributions in a group of Allende inclusions. We previously reported\n(Murrell and Burnett, 1984) on TS-23, a type Bl inclusion. Th and U were found to be enriched greater than 100 x’s Cl with Th/U = 3. 8 ± 0.l in the spinel + perovskite portion\nof the rim on this inclusion. The Ti-Al-rich clinopyroxene band in this rim is also enriched\nin Th and U but with Th/U = 1. In the interior of TS-23, fassaite and melilite were found\nto contain 40 ppb and 90 ppb U, respectively, with little Th-U fractionation. Also, enrichments\nof Th and U to about 80 x's Cl were observed along grain boundaries which contained\nalteration products.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57291,
    title ="Actinide Chemistry of Allende Components",
    author = "Murrell, M. T. and Burnett, D. S.",
    journal = "Meteoritics",
    volume = "19",
    number = "4",
    pages = "275-276",
    month = "December",
    year = "1984",
    
    issn = "0026-1114",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-144742141",
    note = "© 1984 The Meteoritical Society.",
    revision_no = "9",
    abstract = "U and Th in inclusions. Previous reports of high Th/U in Allende Ca,Al-rich inclusions\n(Boynton, 1978; Chen and Wasserburg, 1981; Stapanian, 1981) may indicate that U was not\nacting as a refractory element. The apparent ease of Th/U fractionation in the earliest material\nmakes the ubiquity of Th/U = 3.8 in the solar system hard to understand. U-Th fission track\nradiography offers the possibility of a better understanding of actinide chemistry in Allende\nCa,Al-rich inclusions. Volatility and valence differences between Th and U make these elements\npotentially useful in distinguishing between primary (condensation?) characteristics and those\nproduced later by alteration. A preliminary examination of TS-23 (a type B inclusion provided\nby L. Grossman, 1975) shows U to be highly enriched in the inclusion rim. This result is\nqualitatively similar to that found for U and Th in type A inclusions by Stapanian (1981). ",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56986,
    title ="From outer space; Study of smallest 'dust' offers new challenge",
    author = "Burnett, Donald S.",
    journal = "Geotimes",
    volume = "29",
    number = "6",
    pages = "21-22",
    month = "June",
    year = "1984",
    
    
    issn = "0016-8556",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-073055962",
    note = "© 1984 American Geological Institute.",
    revision_no = "9",
    abstract = "The probability that an extraterrestrial object will be captured without vaporization is a complex function\nof encounter velocity, direction, meteoroid mass, density and strength, among other factors. However, there are two 'windows' that admit material mo re or less intact.\nThrough the big window, objects roughly 10 cm in diameter or larger make it to Earth's surface as meteorites. The small window admits objects of about 1 to 10 microns in size, which escape total vaporization because they rapidly radiate the frictional energy associated with atmospheric entry. Also, the smaller objects have much less kinetic energy, and they therefore slow down higher above Earth, where the atmosphere is less dense.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56985,
    title ="Microprobe analyses of rare earth element fractionation in meteoritic minerals",
    author = "Benjamin, T. M. and Duffy, C. J.",
    journal = "Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms",
    volume = "3",
    number = "1-3",
    pages = "677-680",
    month = "April",
    year = "1984",
    doi = "10.1016/0168-583X(84)90462-2",
    issn = "0168-583X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-070213286",
    note = "© 1984 Published by Elsevier B.V. Available online 17 October 2002.\n\nThis work was supported by the University of California, Institute of Geophysics and Planetary Physics (Grant #82-034), and by the United States Department of Energy, Office of Basic Energy Sciences, under contract KC-040302-0.",
    revision_no = "11",
    abstract = "Two meteorites were analyzed by PIXE with the Los Alamos nuclear microprobe. The enstatite achondrite Peña Blanca Spring and the ordinary chondrite St Severin were chosen as likely candidates for use in ^(244)Pu(t_(l/2)=82 my)  cosmochronology and geochronology. These applications require the meteoritic minerals to have unfractionated actinides and lanthanides relative to “cosmic” elemental abundance ratios. The PIXE analyses produced evidence of actinide-lanthanide fractionation in Peña Blanca Spring oldhamite (CaS) whereas the St Severin phosphates, whitlockite and chlorapatite, do not exhibit this fractionation.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57010,
    title ="Coexisting Chalcophile and Lithophile Uranium in Qingzhen (EH3) Chondrite",
    author = "Rambaldi, E. R. and Rajan, R. S.",
    journal = "Meteoritics",
    volume = "19",
    number = "4",
    pages = "295-295",
    month = "January",
    year = "1984",
    
    issn = "0026-1114",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-121135999",
    note = "© 1984 Meteoritical Society. Provided by the Nasa Astrophysics Data System.",
    revision_no = "7",
    abstract = "Mineralogical and textural studies of Qingzhen have shown that it is highly unequilibrated and that it contains a population of chondrules and isolated enstatite grains which preserve the record of more oxidizing nebular conditions (Rambaldi et al., 1983, 1984). Even though in the\nmajority of cases these objects have been affected by various degrees of reduction, some still contain silicates with high (up to 10%) FeO contents.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56968,
    title ="The behavior of actinides, phosphorus, and rare earth elements during chondrite metamorphism",
    author = "Murrell, M. T. and Burnett, D. S.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "47",
    number = "11",
    pages = "1999-2014",
    month = "November",
    year = "1983",
    doi = "10.1016/0016-7037(83)90216-8",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150424-143531352",
    note = "© 1983 Pergamon Press Ltd. Received 26 January 1983, Accepted 11 August 1983, Available online 14 April 2003.\n\nWe wish to thank J. H. Jones, H. Palme, and F. A. Podosek for their careful and most helpful reviews of this paper and P. Pellas for invigorating discussions. We are indebted to J. R. Arnold, R. S. Clarke, Jr., J. N. Grossman, C. B. Moore, K. Nishiizumi, P. Pellas, G. J. Wasserburg, J. T. Wasson, and D. S. Woolum for providing the meteorite samples used in this study. The cooperation of Grossman and Wasson in sharing the Chainpur sections was of particular importance to us. We thank G. Croxaz and L. M. Ross for their assistance with track replication and S. Riley for his general assistance throughout these experiments. This research was supported by NSF grant EAR 81-21381.",
    revision_no = "8",
    abstract = "New data on the U, Pu, and P distributions in less metamorphosed H-chondrites (type 3–5), coupled with literature results, permit a provisional picture to be assembled of the chemistry of these elements and for the rare earth elements in ordinary chondrites and the changes brought about by chondritic metamorphism. Preferential associations of phosphates with metals and/or sulndes in all chondrites strongly indicate an “initially” siderophile or conceivably chalcophile character for P in ordinary chondrite precursor materials with phosphate subsequently formed by oxidation. This oxidation occurred prior to or during chondritic metal-silicate fractionation. Uranium is initially concentrated in chondrule glass at ~ 100 ppb levels with phosphates (primarily merrillite) in H-3 chondrites being essentially U-free (<20 ppb). As chondrule glass devitrified during metamorphism, U migrated into phosphates reaching ~ 50 ppb in Nadiabondi (H-5) merrillite and 200–300 ppb in merrillite from equilibrated chondrites but “froze out” before total concentration in phosphates occurred. Relative ^(244)Pu fission track densities in the outer 5 μm of olivine and pyroxene grains in contact with merrillite and with chondrule mesostasis in Bremervörde (H-3) give Pu(mesostasis)/Pu(merrillite) <0.01, implying total concentration of Pu in phosphates. Similarly, no detectable Pu (<0.1 ppb) was found in chondrule mesostasis in Tieschitz and Sharps; whereas, direct measurements of tracks in phosphates in H-3 chondrites are consistent with high (≳10 ppb) Pu concentrations. Thus, a strong Pu-P correlation is indicated for ordinary chondrites. There is variable Pu/U fractionation in all chondritic phosphates reaching an extreme degree in the unequilibrated chondrites; therefore, the Pu/U ratio in phosphates appears relatively useless for relative meteorite chronology. Literature data indicate that the REE are located in chondrules in unequilibrated chondrites, most likely in glass; thus there may also be strong Pu/Nd fractionation within these meteorites. Like U, the REE migrate into phosphates during metamorphism but, unlike U, appear to be quantitatively concentrated in phosphates in equilibrated chondrites. Thus relative ages, based on Pu/Nd, may be possible for equilibrated chondrites, but the same chronological conclusions are probably obtainable from Pu concentrations in phosphates, i.e., on the Pu/P ratio. However, Pu/P chronology is possible only for ordinary chondrites; so there appears to be no universal reference element to cancel the effects of Pu chemical fractionation in all meteorites. Available data are consistent with — but certainly do not prove-that variations in Pu/P represent age differences, but if these age differences do not exist, then it is conceivable that the solar system ^(244)Pu/^(238)U ratio, important for cosmochronology, is still lower than the presently accepted value of 0.007.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57001,
    title ="Laboratory actinide partitioning: Whitlockite/liquid and influence of actinide concentration levels",
    author = "Benjamin, T. M. and Jones, J. H.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "47",
    number = "10",
    pages = "1695-1705",
    month = "October",
    year = "1983",
    doi = "10.1016/0016-7037(83)90019-4",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-102542957",
    note = "© 1983 Pergamon Press Ltd. Received 6 August 1982, Accepted 27 June 1983. \n\nThis research was supported by NASA grant NSG 7202. We thank M. T. Murrell for helpful discussions. The manuscript profited greatly from reviews by E. Dowty and L. Haskin.",
    revision_no = "8",
    abstract = "Fission and alpha track radiography techniques have been used to measure partition coefficients (D) at trace (ppm) concentration levels for the actinide elements Th, U, and Pu between synthetic whitlockite and coexisting “haplobasaltic” silicate liquid at 1 bar pressure and 1250°C at oxygen fugacities from 10^(−8.5) and 10^(−0.7) bars. Pu is much more readily incorporated into crystalline phases than is U or Th under reducing conditions (fO_2 = 10^(−8.5)), because Pu is primarily trivalent, whereas U and Th are tetravalent. Definitive valence state assignments cannot be made, but our best estimates of corrected partition coefficients for Pu^(+3), Pu^(+4), Th^(+4), U^(+4), and U^(+6) are, for whitlockite 3.6/<⩽0.6/1.2/0.5/⩽0.002. The effect of changing pressure and liquidus temperature is relatively small, which probably reflects a weak temperature dependence for D (whitlockite) but possibly could be due to cancellation of opposing temperature and pressure effects. Comparison of experiments at trace U levels with those containing percent concentrations of UO_2 indicate that Si is involved in the substitution of U in whitlockite with U + 2Si ⇄ Ca + 2P being the most likely mechanism. D_u is lower. 0.3 vs 0.5. at percent levels compared to 20 ppm. This is best explained by the effect of U on melt structure or by a decrease in the fraction of tetravalent U at high U concentrations.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51118,
    title ="Retention of ion-implanted-xenon in olivine: Dependence on implantation dose",
    author = "Melcher, C. L. and Tombrello, T. A.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "47",
    number = "10",
    pages = "1707-1712",
    month = "October",
    year = "1983",
    doi = "10.1016/0016-7037(83)90020-0 ",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141031-103904895",
    note = "© 1983 Pergamon Press Ltd.\n\nReceived February 3, 1983; Accepted in revised form June 28, 1983.\n\nWe are grateful to T. Banwell for performing\nthe implantations and to T. J. Ahrens for the single\ncrystal forsterite. This work was supported by the NSF\n[PHY79-23638] and NASA [NAGW-148].",
    revision_no = "9",
    abstract = "The diffusion of Xe in olivine, a major mineral in both meteorites and lunar samples, was studied. Xe ions were implanted at 200 keV into single-crystal synthetic-forsterite targets and the depth profiles were measured by alpha particle backscattering before and after annealing for 1 hour at temperatures up to 1500°C. The fraction of implanted Xe retained following annealing was strongly dependent on the implantation dose. Maximum retention of 100% occurred for an implantion dose of 3 × 10^(15) Xe ions/cm^2. Retention was less at lower doses, with ≥ 50% loss at 1 × 10^(14) Xe ions/cm^2. Taking the diffusion coefficient at this dose as a lower limit, the minimum activation energy necessary for Xe retention in a 10 μm layer for 10^7 years was calculated as a function of metamorphic temperature. For example, an activation energy of 50 kcal/mole implies Xe retention may be possible for metamorphic temperatures below 500°C.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56938,
    title ="In Situ Trace Element Microanalysis",
    author = "Burnett, D. S. and Woolum, D. S.",
    journal = "Annual Review of Earth and Planetary Sciences",
    volume = "11",
    
    pages = "329-358",
    month = "May",
    year = "1983",
    doi = "10.1146/annurev.ea.11.050183.001553",
    issn = "0084-6597",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150424-082233103",
    note = "© 1983 by Annual Reviews Inc.\n\nMuch of the research discussed in this paper was supported by NASA through grants NSG 7202 (DSB) and NSG 7314 (DSW) and by NSF grant EAR 8121381 (DSB).",
    revision_no = "9",
    abstract = "We define in situ trace element microanalysis as the measurement of\nconcentrations of trace elements (< 1000 ppm) in individual mineral phases\nin polished sections, analogous to electron microprobe analysis for major\nelements. It is our opinion that such measurements are important and can\nprovide a new dimension to petrology and geochemistry. This article is\nboth a review of work already done and a summary of potential advances in\nthe future. The advantages of in situ analyses, as opposed to methods\ninvolving physical and/or chemical mineral separations, are that the trace\nelement data can be interpreted in a petrographic context and that\nambiguities associated with the purity of the mineral separates can be\navoided. With data on individual grains, comparisons of intergrain and\nintragrain (zoning) variations between major and trace elements can be\nmade, and the importance of inclusions can be assessed, within the spatial\nresolution of the microanalysis technique.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56950,
    title ="Chemical History with a Nuclear Microprobe",
    author = "Maggiore, C. J. and Benjamin, T. M.",
    journal = "IEEE Transactions on Nuclear Science",
    volume = "30",
    number = "2",
    pages = "1224-1227",
    month = "April",
    year = "1983",
    doi = "10.1109/TNS.1983.4332494 ",
    issn = "0018-9499",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150424-103241147",
    note = "© 1983 IEEE.\n\nThe authors wish to acknowledge the help and support of the Laboratory's Van de Graaff group. This work was supported by the United States Department of Energy.",
    revision_no = "9",
    abstract = "A nuclear microprobe cannot give direct information on the chemical state of an element, but the spatial distribution of elements in a specimen is often determined by the chemical history of the sample. Fuel cells and minerals are examples of complex systems whose elemental distributions are determined by past chemical history. The distribution of catalyst in used fuel cell electrodes provides direct information on the chemical stability of dispersed catalysts under operating conditions. We have used spatially resolved Rutherford backscattering to measure the migration of platinum and vanadium from intermetallic catalysts and to determine their suitability for use under the extreme operating conditions found in phosphoric acid fuel cells. Geologic materials are complex, heterogeneous samples with small mineral grains. The trace element distribution within the individual mineral grains and between different mineral phases is sensitive to the details of the mineral formation and history. The spatial resolution and sub-100-ppm sensitivity available with a nuclear microprobe open up several new classes of experiments to the geochemist. Geochemistry and electrochemistry are two areas proving particularly fruitful for application of the nuclear microprobe.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56966,
    title ="Actinide microdistributions in the enstatite meteorites",
    author = "Murrell, M. T. and Burnett, D. S.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "46",
    number = "12",
    pages = "2453-2460",
    month = "December",
    year = "1982",
    doi = "10.1016/0016-7037(82)90368-4 ",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150424-142033701",
    note = "© 1982 Pergamon Press Ltd.\n\nReceived May 5, 1982; accepted in revised form August 23, 1982.\n\nThis paper has benefited from the careful reviews of G. Crozaz and K. Marti. We are indebted to R. Clarke (U.S. National Museum), R. Hutchison (British Museum of Natural History), G. Kurat (Naturhistorisches Museum, Wien) and J. T. Wasson for providing the meteorite samples used in this study. We are grateful for the excellent cooperation of the LBL 88-in. cyclotron staff, in particular Ruth Mary Larimer. Also, Dorothy Woolum provided essential hardware and guidance in the cyclotron irradiation. We are pleased to acknowledge the help of R. S. Rajan in the etching of ^(244)Pu fission tracks. We thank W. R. Heuser for experimental assistance and Lou Ann Cordell and Bernice Taylor for typing this paper. This research was supported by NSF grant EAR79-20091.",
    revision_no = "9",
    abstract = "Oldhamite is a major Th and U bearing phase in the enstatite meteorites. Oldhamite from E-6 chondrites has mean Th and U abundances of 1550 ± 80 ppb Th and 410 ± 20 ppb U, with Th/U = 3.8 ± .2. With the exception of ferroan alabandite which contains 25 ± 1 ppb U, no other Th or U enriched phases were located in the E-6 chondrites, and nearly all of the total rock Th and U can be accounted for by oldhamite. In Khairpur (E6), excess fossil fission tracks were observed in enstatite grains in contact with oldhamite which indicates the presence of ^(244)Pu in oldhamite. Oldhamite from St. Mark's (E5) and Abee (E4) also shows actinide enrichments but at levels about half the E-6 results. Niningerite in Abee contains 45 ± 5 ppb U and due to its high reported modal abundance is an important U reservoir in Abee. The U content of oldhamite from the aubrite Peña Blanca Spring is 1920 ± 100 ppb. All Th/U values measured in this study cluster tightly around a value of 4 which indicates a lack of Th-U fractionation in both oldhamite and in the enstatite meteorites, themselves. This lack of fractionation, along with the presence of ^(244)Pu in oldhamite and reported rare earth enrichments also in oldhamite, suggests that the enstatite chondrites may be well-suited for Pu-U chronology and for providing the initial Pu-U value in the early solar system.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56987,
    title ="Trace elements in Peña Blanca Spring Oldhamite",
    author = "Woolum, D. S. and Burnett, D. S.",
    journal = "Meteoritics",
    volume = "17",
    number = "4",
    pages = "299",
    month = "December",
    year = "1982",
    
    issn = "0026-1114",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-075908537",
    note = "© 1982 Meteoritical Society. Provided by the NASA Astrophysics Data System.",
    revision_no = "11",
    abstract = "Murrell and Burnett (M-B) ( 1982) reported that oldhamite (CaS) is the primary host phase of U and Th in the E6 chondrites. E-chondrite Th/U values were all cosmic, indicating a lack of Th-U fractionation in both oldhamite and in the bulk meteorites. In Khairpur (E6), they attributed excess fossil fission tracks to the presence of 244Pu in oldhamite. Rare earth (REE) enrichments were\ninferred for an Abee (E4) water soluble phase(s) (Frazier and Boyton, 1981), presumably oldhamite, and perhaps niningerite. These led M-B to suggest that the enstatite chondrites may be well-suited for Pu-U chronology and possibly for providing the initial Pu/U Value in the solar system.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56939,
    title ="Thorium-uranium fission radiography II",
    author = "Murrell, M. T. and Burnett, D. S.",
    journal = "Nuclear Instruments and Methods",
    volume = "199",
    number = "3",
    pages = "617-621",
    month = "August",
    year = "1982",
    doi = "10.1016/0167-5087(82)90163-6 ",
    issn = "0029-554X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150424-083121620",
    note = "© 1982 North-Holland Publishing Company.\n\nReceived 7 July 1981 and in revised form 4 January 1982.\n\nWe are grateful for the excellent cooperation of the LASL LAMPF staff, in particular B. Dropesky and L. Ulibari. We thank W.R. Heuser for experimental assistance and Lou Ann Cordell for typing this paper. This research was supported by NSF grants EAR79-20091 and PHY79-23638.\n\n",
    revision_no = "9",
    abstract = "The high energy secondary neutron flux produced by 500–650 MeV protons at the beam stop of the Los Alamos Meson Physics Facility (LAMPF) is evaluated for use in measuring the micro distribution of thorium in geologic materials, e.g. in individual mineral grains, ≳50 µm in size. The relative Th/U fission rate is found to be 0.5 with a Th track production rate of 1.2×10^4 tracks/cm^2•ppm•mAh. The background of long interaction tracks (⩽10 μm) limits the sensitivity of this method to samples of 3–5 ppm Th. We find a similar background of long interaction tracks in a LAMPF proton irradiation.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57282,
    title ="Meteoritic Bismuth and ^(208)Pb Microdistributions",
    author = "Woolum, Dorothy S. and Burnett, D. S.",
    journal = "Transactions of the American Nuclear Society",
    volume = "41",
    
    pages = "191-192",
    month = "June",
    year = "1982",
    
    
    issn = "0003-018X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150506-130253747",
    note = "© 1982 American Nuclear Society.",
    revision_no = "9",
    abstract = "Certain types of meteorites are believed to be the most\nprimitive solar system objects available. Bismuth and lead\nmicrodistributions in these are of interest because (a) predictions\nfor the condensation of these elements are available\nfrom thermodynamic calculations for equilibrium, gas-to-solid\ncondensation in a cooling nebula of solar composition;\n(b) based on this theory, bulk bismuth contents have been\nused for inferring the temperatures at which solids in the\nsolar nebula accreted, as well as the extant nebular pressures;\nand (c) due to their volatility, these elements are easily\nmobilized in metamorphic (reheating) events and are thus\nsensitive indicators of planetary processing of the meteoritic\nmaterial. With the idea of testing, where possible, the\nequilibrium condensation theory (a) and its ramifications (b)\nand of assessing the nature and evolution of early bodies in\nthe solar system (c), we have been studying the bismuth and\n^(208)Pb microdistributions in unequilibrated chondritic meteorites.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51519,
    title ="Observation of non-lithophile behavior for U",
    author = "Furst, Marian J. and Stapanian, Maritza I.",
    journal = "Geophysical Research Letters",
    volume = "9",
    number = "1",
    pages = "41-44",
    month = "January",
    year = "1982",
    doi = "10.1029/GL009i001p00041",
    issn = "0094-8276",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141110-131602950",
    note = "Copyright 1982 by the American Geophysical Union. \n\n(Received August 3, 1981; accepted October 19, 1981.) \n\nPaper number 1L1659. \n\nThe Hvittis sample was generously provided by Roy Clarke, U.S. National Museum. We thank M. Murrell, E. Stolper and K. Goettel for helpful discussions. Research support was by NSF grant EAR79-20091A-1. Caltech Contribution No. 3656.",
    revision_no = "9",
    abstract = "In the Hvittis enstatite chondrite fission track radiography shows that U is highly concentrated in CaS (oldhamite), with a concentration of 400±50 ppb. The oldhamite U concentrations are equilibrated, although intergrain concentration variations of less than 15% would not be detected. Various approaches to a U material balance do not agree, but at least 50% and, more likely, nearly 100% of the U is concentrated in CaS. It is likely that CaS is the major reservoir for other actinide and lanthanide elements as well. Consequently, enstatite chondrites may provide reliable Pu/U abundance ratios. The highly reducing formation conditions for enstatite chondrites have caused U to deviate from lithophile behaviour, but K is observed to remain lithophile. Although this observation may not be generalizable, we propose that discussions of radioactive heating of planetary cores should include U and Th and not focus exclusively on K.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56989,
    title ="Extreme Pu-U and Possible Pu-REE Fractionation in Unequilibrated Chondrites",
    author = "Murrell, M. T. and Burnett, D. S.",
    journal = "Meteoritics",
    volume = "17",
    number = "4",
    pages = "256-257",
    month = "January",
    year = "1982",
    
    issn = "0026-1114",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150427-082945452",
    note = "© 1982 Meteoritical Society. Provided by the Nasa Astrophysics Data System.",
    revision_no = "15",
    abstract = "The purpose of this study is to understand actinide chemistry in chondrites and to evaluate unequilibrated chondrites for either Pu/U or Pu/Nd chronology. Using fission track radiography for Nadiabondi (H5/(Murrell and\nBurnett, 1982), Dhajala (H3,4), Bremervorde (H3), Sharps (H3), and Tieschitz (H3), we find that U is primarily located in chondrule glass (50-500 ppb, average of ~ 100 ppb). Apatite from the unequilibrated chondrites contains\n150-200 ppb U while whitlockite contains < 17 ppb [low compared to type-6 chondrites which have 1-6 ppm U in apatite and ~ 200 ppb in whitlockite (Pellas and Storzer, 1975)]. Nadiabondi phosphates are intermediate (Murrell and Burnett, 1982). These observations suggest that the phosphate U content increases with petrologic type (Pellas and Storzer, 1975), with U obtained from chondrule glass during metamorphism.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/57242,
    title ="SiO2-rich condrules in ordinary chondrites",
    author = "Brigham, Cheryl and Murrell, M. T.",
    journal = "Meteoritics",
    volume = "17",
    number = "4",
    pages = "187-188",
    month = "January",
    year = "1982",
    
    issn = "0026-1114",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150505-140925448",
    note = "© 1982 Meteoritical Society.",
    revision_no = "14",
    abstract = "The solar system abundances of Mg, Fe, and Si dictate that chondritic meteorites are silica-deficient compared to most terrestrial or lunar igneous rocks; thus olivine-orthopyroxene assemblages are commonly observed in ordinary chondrites. However, in the unequilibrated H-chondrites Sharps, Bremervorde, and Dhajala, we have observed chondrules and fragments which contain either tridymite or cristobalite as a major phase.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56974,
    title ="Th/U Microdistribution in Enstatite Meteorites",
    author = "Murrell, M. T. and Burnett, D. S.",
    journal = "Meteoritics",
    volume = "16",
    number = "4",
    pages = "363",
    month = "December",
    year = "1981",
    doi = "10.1111/j.1945-5100.1981.tb00687.x",
    issn = "0026-1114",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150424-150326974",
    note = "© 1981 The Meteoritical Society.",
    revision_no = "9",
    abstract = "We report here our results to date for the mineralogical distribution of Th and U in the enstatite chondrites. By investigating the behavior of Th and U under the reducing conditions for which the enstatite meteorites formed, we hope to evaluate the suitability of these objectives for ^(244)Pu(_(1/2) = 82 m.y .) chronology, as well as gain  insight into the origin of the E-chondrites. Induced fission tracks from a double irradiation have been used to map the distribution of Th and U in polished sections. The preliminary results are shown in Table I. The values are the mean contents of oldhamite (CaS) grains, and the uncertainties are the standard deviations from the mean.\nIn enstatite chondrites both Th and U are concentrated in oldhamite. For example, in a section of Daniel's Kuil at least 70% of the total Th and 90% of the U are found in oldhamite. In Khairpur, alabandite (MnS) was also found to contain U but at a lesser concentration (~20 ppb). The smaller oldhamite grain size in St. Mark's and Abee complicates their study; however, Th+U are also found to concentrate in oldhamite in these two meteorites but at a somewhat lower value than seen in the E-6's. The Th-U ratios in oldhamite determined so far appear relatively unfractionated from the typical value of ~4. The whole rock Th/U value forHvittis was reported to be 5.0 (Morgan and\nLovering, 1968) which agrees well with the oldhamite result. However, the whole rock Th/U for Khairpur of 2.5 (Morgan and Lovering, 1968) does not agree with the  oldhamite value. This discrepancy will be investigated in an upcoming irradiation; in this irradiation we also hope to\ncomplete the data set of Table 1, look at Th/U on a grain-by-brain basis and examine the U distribution\nin a few enstatite achondrites (aubrites). But with the results to date, a good case can be made for a study of ^(244)Pu in the E-6 chondrites. The majority of Th and U is concentrated with little apparent fractionation in a single mineral, and the particular chemistry of oldhamite should enable a selective Pu-Xe measurement to be made.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56904,
    title ="Metal and Bi/Pb microdistribution studies of an L3 chondrite:\ntheir implications for a meteorite parent body",
    author = "Woolum, Dorothy S. and Burnett, D. S.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "45",
    number = "9",
    pages = "1619-1632",
    month = "September",
    year = "1981",
    doi = "10.1016/0016-7037(81)90290-8",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150423-093035716",
    note = "© 1981 Pergamon Press Ltd.\n\nReceived 19 August 1980, Accepted 8 May 1981, Available online 27 March 2003.\n\nThe authors gratefully acknowledge the technical advice and support and the splendid cooperation we have enjoyed at the 88-in. cyclotron at the Lawrence Berkeley Lab; in particular, we wish to thank G. WELCH, whose beam scanner we used, H. HARRINGTON, H. WIEMAN. D. SCOTT, and especially RUTH MARY LARIMER. Laboratory assistance from RONALD MASCITELLI and JIM CONCA is also much appreciated. DSW enjoyed the hospitality of the Harvard Smithsonian Center for Astrophysics and the Physics Department and the Laboratory for Nuclear Science at MIT in the final stage of this work and particularly wants to thank JOHN WOOD and KAREN MOTYLEWSKI for their help and for the use of their electron microprobe and SEM. ALAN DUBROC and LOU ANN CORDELL cheerfully prepared this manuscript. We are indebted to M. PRINZ of the American Museum for the Khohar (KAM) sample; the KB section came from the Caltech meteorite collection. This research was made possible by NASA grant NSG 7314.",
    revision_no = "12",
    abstract = "We find strong localizations (relative to bulk) of Bi and to a lesser extent Pb. in some of the kamacite grains in Khohar. Other kamacite grains show no such enrichments. There are distinctive and correlated differences in the Ni contents of the two kamacite populations, with the Bi/Pb-rich kamacite grains having consistently lower Ni levels (sometimes unusually low. ~ 2% Ni) than the Bi/Pb-poor kamacite, which typically have ~ 6–7% Ni. The Bi/Pb-rich kamacite grains are also distinguished on the basis of their etching behavior, exhibiting a highly reactive attack, which has not been observed previously and which we believe may be due to the fact that the Bi/Pb-rich kamacite is finely polycrystalline.\n\nWe conclude that the trace element microdistributions were not established in the nebula. Nor is it likely that the enrichments occurred with slow cooling in the presence of a vapor phase during the kamacite-taenite phase transition. Rather, the Bi/Pb-rich kamacite most likely reflect the occurrence of a brief reheating episode (or episodes), which may have been shock-induced and which was followed by rapid cooling. We find fine-grained metal-sulfide intergrowths which testify to such a reheating event, and one likely candidate for the site of this event is a hot ejecta blanket at the parent body surface. Iron oxides are found in our Khohar sections. We believe that they are not due to terrestrial alteration, that they are magnetite and that the magnetite probably originated in the same dynamic event in which the Bi/Pb distributions were established. The present data do not allow us to confidently determine whether the event occurred prior to, during, or after the compaction of this meteorite, although the simplest interpretation of the data would indicate the first alternative. Bulk Bi data for Khohar has been used for inferring accretion temperatures and this now appears inappropriate.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56942,
    title ="Quantitative radiography using Ag X-rays",
    author = "Jones, John H. and Burnett, Donald S.",
    journal = "Nuclear Instruments and Methods",
    volume = "180",
    number = "2-3",
    pages = "625-633",
    month = "April",
    year = "1981",
    doi = "10.1016/0029-554X(81)90108-7",
    issn = "0029-554X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150424-090103969",
    note = "© 1981 North-Holland Publishing Company. Received 11 August 1980.",
    revision_no = "8",
    abstract = "We have used an electron microprobe or scanning electron microscope to analyze the Ag produced by exposure of Ilford nuclear emulsions to ^(151)Sm beta particles. The low beam currents of the SEM yielded satisfactory results while the higher current density of the microprobe produced variable amounts of volatilization of the organic constituents of the emulsion. Nonlinearities in Ag counting rate vs. exposure time curves were found at both high and low Ag concentrations. Two different types (mechanisms?) of emulsion fading were observed, one operating on an hour, the other on a day, time scale. The low-Ag nonlinearities are perhaps explained by either dose-dependent short time scale fading or by the requirement of multiple hits to render some AgBr grains developable.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56889,
    title ="K-U Studies of Silica-Rich Inclusions in the Shaw Chondrite",
    author = "Heuser, W. R. and Burnett, D. S.",
    journal = "Meteoritics",
    volume = "15",
    number = "12",
    pages = "301-302",
    month = "December",
    year = "1980",
    
    issn = "0026-1114",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150422-145412068",
    note = "© 1980 Meteoritical Society. Provided by the NASA Astrophysics Data System.",
    revision_no = "8",
    abstract = "The K/U can be regarded as a \"planetary constant\" which is invariant during magmatic processes but which differs for cosmochemical reasons between planets. This assumption is\nuniversal in all thermal history calculations for planets. K-SiO_2-rich inclusions are found in Shaw which many authors believe is a chondrite which has been subjected to partial melting (Taylor et al., 1979; Rambaldi and Lamimer, 1976). Although the origin of these inclusions is not well understood, it is possible that they represent the first melts or magmatic fluids produced in the formation of planets. Thus it is of interest to see if U and Th have followed K into these liquids. For the case of Shaw some evidence of K/REE fractionation already exists (Rambaldi and Lamimer, 1976). Six polished sections of Shaw with affixed mica fission track detectors were irradiated with\n~ 2 x 10^(18)/cm^2 thermal neutrons. Excellent fission track images were obtained with no evidence for any significant contamination. (Random scans on our most-studied section gave 6 ppb U.) The fission track distributions show a high degree of localization. In one section, mapped in great detail, 20-30 large (> 50 micron) fission track localizations, can all be accounted for by whitlockite and chloroapatite. The whitlockite U concentrations (300-700 ppb) are variable, but typical for\nchondrites. The phosphate grains serve as fiducial points, allowing accurate location of the melt inclusions on the mica track detector (maximum position error= 20 microns). In many cases no localizations of tracks are found (U contents < 10 ppb) corresponding to the K-Si-rich inclusions, but in 7/25 cases localizations are found with U concentrations up to ~ 300 ppb. The inclusions are small (usually< 20μ), and there are many other small track localizations in this size range which have no obvious sources, thus some of these 7 cases may be accidental. However, track mapping at 13 random fields of view showed only 2 localizations (track density 3-4 times surroundings) within 20 microns. The small track localizations of unknown origin can be explained by a combination of buried sources (within 10 microns of surface), local contamination (which can never be ruled out) or localization of U on grain boundaries or cleavage planes in major phases. There is no correlation of U content with inclusion chemistry (K), size, opaque mineralogy, or petrographic location. Many of the inclusions are within large (hundreds of microns) olivine grains, including some that seem U-rich. In two of these cases the track localizations stand out from an almost blank background and match the location and size of the inclusion. It seems inescapable that the tracks do\narise from the inclusions in these cases. It may be that these inclusions were a preferential site of contamination during sample preparation or by terrestrial weathering, but it is also possible that U-bearing phases only occasionally participated in the partial melting process. It may be significant that the inclusions contain no P, thus this U reservoir has not participated. Regardless, the important\nresult is that in most cases K was mobilized to a much higher degree than U in the Shaw partial melting event. (The inclusion KIU is at least 10x bulk chondrites.) Although the inclusions are relatively Fe-rich, the concentration of K and Si and the exclusion of U and rare-earths follows the chemical systematics of immiscible silicate melts (Watson, 1976; Ryerson and Hess, 1978). To the extent that Shaw is representative of very small degrees of partial melting in planets, K and U appear to be fractionated.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56918,
    title ="Actinide crystal-liquid partitioning for clinopyroxene and Ca_3(PO_4)_2",
    author = "Benjamin, T. and Heuser, W. R.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "44",
    number = "9",
    pages = "1251-1264",
    month = "September",
    year = "1980",
    doi = "10.1016/0016-7037(80)90086-1",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150423-112316141",
    note = "© 1980 Pergamon Press Ltd. Received 20 August 1980, Accepted 15 April 1981, Available online 4 April 2003.\n\nWE acknowledge profitable discussions with J. JONES and B. O. MYSEN and thoroughly reviews by J. A. PHILPOTTS, W. BOYNTON and A. J. IRVING. This research was supported by NASA grant NSG-7202.",
    revision_no = "9",
    abstract = "Using fission and alpha track radiography techniques, we have measured partition coefficients (D) for the actinide elements Th, U and Pu between diopsidic clinopyroxene, whitlockite [β-Ca_3 (PO_4)_2] and silicate liquid at 20kbar. Equilibrium partitioning at the crystal-liquid interface is assumed, and corrections for actinide zoning have been applied to the measured D values. Reproducibility for both actinide and minor element D values is carefully examined as a criterion for crystal-liquid interface equilibrium. The data are mostly compatible with interface equilibrium except for experiments at high cooling rates ( ⪸ 30 deg/hr). Partition coefficients for Th/U/Pu of about 0.002/0.002/0.06 are measured for clinopyroxene and 1.2/0.5/3.4 for whitlockite. At an oxygen fugacity of 10^(−8.5), Pu is much more readily incorporated into the crystalline phases than is U or Th because of the importance of trivalent Pu. The D_(Pu)(cpx) is similar to D(cpx) of the light rare earths supporting the concept of Pu/(rare earth) dating.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56911,
    title ="The distribution of U and Pu in the St. Severin chondrite",
    author = "Jones, J. H. and Burnett, D. S.",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "43",
    number = "12",
    pages = "1895-1905",
    month = "December",
    year = "1979",
    doi = "10.1016/0016-7037(79)90003-6",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150423-101709795",
    note = "© 1979 Pergamon Press Ltd. Received 5 February 1979, Accepted 31 July 1979.\n\nThe St. Severin samples were obtained through the co-operation of P. PELLAS J. REYNOLDS and G. J. WASSERBURG. We thank F. OBERLI and G. J. WASSERBURG for isotopic dilution measurements of our glass standards. We acknowledge profitable discussions with T. BENJAMIN and P. PELLAS and very thorough reviews by G. CROZAZ and G. LUGMAIR. We also thank Lou ANN CORDELL and BETTY ROBINKIN for their skill and patience. This research was supported by NSF grant EAR76-84402.",
    revision_no = "8",
    abstract = "A detailed study of the U distribution of the St. Severin chondrite has been made by fission track radiography in order to clarify the interpretation of fission Xe thermal release data in terms of the mineralogical location of the fission Xe within the meteorite. This is of importance because the ^(244)Pu/^(238)U ratio for St. Severin has been widely adopted as the average solar system value. The U contents of the constituent minerals cannot account for the total rock U which, instead, appears to be primarily localized on grain boundaries. The greatest localizations of U are in olivine-poor, orthopyroxene-rich ‘clasts’. Our data coupled with those of Podosek (1970a) show that ^(244)Pu in St. Severin was also located on grain boundaries and that the bulk of Pu and U are unfractionated within this meteorite. Due to recoil, the ^(244)Pu fission Xe is found in 10 micron surface layers on major phases. Assuming that the grain boundaries (on which the Pu was located) was formed during metamorphism, the ^(244)Pu/^(238)U ratio for St. Severin applies to a time subsequent to the textural recrystallization of the meteorite. Our data support the interpretation of Podosek and our best estimate of the solar system ^(244)Pu/^(238)U is 0.015.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/56914,
    title ="Bismuth and ^(208)Pb microdistributions in enstatite chondrites",
    author = "Woolum, Dorothy S. and Bies-Horn, Linda",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "43",
    number = "11",
    pages = "1819-1828",
    month = "November",
    year = "1979",
    doi = "10.1016/0016-7037(79)90030-9",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150423-103355055",
    note = "© 1979 Pergamon Press Ltd. Received 4 August 1978, Accepted 18 July 1979, Available online 4 April 2003.\n\nwe are indebted to R. CLARKE (U.S. National Museum) E. OLSEN (Field Museum, Chicago), and J. T. WASSON for their cooperation in providing the meteorite samples used in this study, and we thank G. MILLER, R. B. THEUS and R. 0. BONDELID of the NRL cyclotron for their support and interest in these experiments. The hospitality extended to us by the Geophysical Lab, where we do the photomicroscopy for the short Bi exposures after our irradiations, is very much appreciated. Finally, we are pleased to acknowledge the assistance of R. MASCITELLI in the analysis of the track registration and micro-migration experiments, and J. GRIFFITH in the tandem irradiations. This research was supported by NSF grant EAR73-00245 A02 and NASA grant NSG 7314.",
    revision_no = "8",
    abstract = "Polished sections of 5 enstatite chondrites have been irradiated with 30 MeV ^4He ions to produce the alpha-radioactive nuclei ^(211)At and ^(210)Po from ^(209)Bi and ^(208)Pb, respectively. The distribution of alpha activity can be mapped, using cellulose nitrate as an alpha track detector, to give the corresponding Bi or Pb distributions in the meteorite. No strong localization of Bi or ^(208)Pb was found; relatively uniform track distributions were observed. In particular, metal or sulfide grains are not enriched in Bi or Pb (relative to bulk), which is in agreement with the predictions of nebular condensation calculations. While the track distributions appear uniform, the results of detailed, track-by-track mappings of the Bi detectors indicate that the Bi is not totally randomly distributed; the statistical fluctuations in the observed track density are different for the cases where the Bi is totally randomly distributed and where the Bi is localized in point sources. Assuming that the Bi in a given sample is localized in identical point sources which are uniformly distributed throughout the sample, the observed relative population densities of clusters (‘stars’) of small numbers of tracks (2–5) corresponds to Bi being localized, with ~90% in grains with about 10^(−16)g-Bi (~3 × 10^5 Bi atoms), and with ~10% in 4 × 10^(−14) g-Bi sources. If these are elemental Bi, as predicted theoretically, they are ~ 10^2 Å and 10^3 Å in size, respectively.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/54730,
    title ="Boron concentrations in carbonaceous chondrites",
    author = "Weller, Martha Riherd and Furst, Marian",
    journal = "Geochimica et Cosmochimica Acta",
    volume = "42",
    number = "7",
    pages = "999-1009",
    month = "July",
    year = "1978",
    doi = "10.1016/0016-7037(78)90289-2",
    issn = "0016-7037",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150211-124825676",
    note = "© 1978 Published by Elsevier Ltd. Received 26 October 1977; accepted in revised form 24 February 1978.\n\nMeteorite samples for this study were generously supplied by R. CLARKE (U.S. National Museum), E. OLSEN (Field Museum, Chicago), C. MOORE (Arizona State), G. J. WASSERBURG (Caltech) and J. WASSON (U.C.L.A.). We profited greatly from a discussion with D. HEYMANN on ^(10)Be production. The co-operation of the U.C.L.A. Nuclear Energy Laboratory in arranging reactor irradiations is acknowledged. This work was supported by NSF Grants EAR 76-84402 (D. S. Burnett) and PHY\n76-83685 (T. Tombrello).",
    revision_no = "12",
    abstract = "We have analyzed B in carbonaceous chondrites in order to clarify a factor of 100 difference between the solar system B abundance derived from the solar photosphere and that inferred from previous meteorite data. Consistent results were obtained from two instrumental methods for B analysis: (a) counting of the high energy betas from ^(12)B produced by the ^(11)B(d,p) reaction, and (b) measurement of particle track densities from ^(10)B(n,α)^7Li in a plastic track detector affixed to a homogenized meteorite sample. Contamination is a major problem in B analyses, but extensive testing showed that our results were not seriously affected. Our B concentrations are typically 1–2 ppm and are a factor of 2–6 lower than previous carbonaceous chondrite measurements. Our data for the Cl chondrites Ivuna and Orgueil would indicate a solar system B/Si atomic abundance ratio of 58 × 10^(−6), but this is still a factor of 2–10 higher than the photospheric estimates. It may be that B is depleted in the sun by thermonuclear processes; however, the similarity of photospheric and meteoritic Be abundances is a problem for this point of view. Alternatively, B may be enhanced in carbonaceous chondrites, but this would make B a cosmochemically unique element. A mm-sized (Fe,Mn,Mg)CO_3 crystal from Orgueil shows no B enrichment. We find ^(10)B ≤ 10^(16) atoms/g in two Allende fine-grained inclusions suggesting that B is not a refractory element under solar nebula conditions. This ^(10)B limit, when taken as a limit on ^(10)Be when the inclusion formed, puts constraints on the possibility of a solar system synthesis of ^(26)Al. For a proton spectrum of E^(−a), a must be ≥ 3 if a solar gas is irradiated or a ≥1.5 if dust of solar composition is irradiated.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51343,
    title ="Mass fractionation of the lunar surface by solar wind sputtering",
    author = "Switkowski, Z. E. and Haff, P. K.",
    journal = "Journal of Geophysical Research",
    volume = "82",
    number = "26",
    pages = "3797-3804",
    month = "September",
    year = "1977",
    doi = "10.1029/JB082i026p03797",
    issn = "0148-0227",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141105-155414599",
    note = "Copyright 1977 by the American Geophysical Union. \n\n(Received September 13, 1976; revised May 5, 1977; accepted May 5, 1977.) \n\nPaper number 7B0384. \n\nThis work was supported in part by the National Science Foundation (PHY76-83685) and the National Aeronautics and Space Administration (NGR 05-002-333).",
    revision_no = "9",
    abstract = "The sputtering of the lunar surface by the solar wind is examined as a possible mechanism of mass fractionation. Simple arguments based on current theories of sputtering and the ballistics of the sputtered atoms suggest that most ejected atoms will have sufficiently high energy to escape lunar gravity. However, the fraction of atoms which falls back to the surface is enriched in the heavier atomic components in relation to the lighter ones. This material is incorporated into the heavily radiation-damaged outer surfaces of grains, where it is subject to resputtering. Calculations predict that an equilibrium surface layer, enriched in heavier atoms, will form with δ(^(18)O) ≈ +20‰ ≈ δ(^(30)Si) and that oxygen will be depleted on the surface layers of grains relative to the bulk composition by about 12.5%. These results are in fair agreement with experiment. The dependence of the calculated results upon the energy spectrum of sputtered particles is investigated. We conclude that mass fractionation by solar wind sputtering is likely to be an important phenomenon on the lunar surface but that the complex isotopic variations observed in lunar soils cannot be completely explained by this mechanism.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/60026,
    title ="The solar system boron abundance",
    author = "Weller, Martha Riherd and Furst, Marian",
    journal = "Astrophysical Journal",
    volume = "214",
    
    pages = "L39-L43",
    month = "May",
    year = "1977",
    
    issn = "0004-637X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20150902-104155655",
    note = "© 1977 American Astronomical Society. Received 1976 October 7; revised 1977 January 19.\n\nSupported in part by the National Science Foundation\n[EAR73-00245A02, PHY76-02724].\nWe thank C. Moore, R. Clarke (U.S. National Museum), J. Lovering, E. Olsen (Chicago Museum of Natural History), J. Wasson, and G. J. Wasserburg for the meteorite samples.",
    revision_no = "9",
    abstract = "The concentrations of B in seven carbonaceous chondritic meteorites have been determined by the use of two different analytical techniques. The data correspond to a B/H ratio of about 10^(-9) compared to the value of 10^(-8) previously proposed by Cameron, Colgate, and Grossman. However, the meteoritic abundance remains at least a factor of 2-10 higher than various estimates of the solar\nphotosphere abundance. We conclude that both meteoritic and photospheric B and Be abundances must be considered in comparisons with nucleosynthesis calculations. Using our revised B abundances and assuming ^7Li was synthesized in the big bang, we find that the residual ^6Li/1°B, ^9Be/^(10)B, and ^(11)B/^(10)B abundance ratios are well matched by the production rates for bombardment of a CNO\nmixture of solar proportions by protons and a-particles with a kinetic energy per nucleon spectrum of the form E^(-1.8).",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51348,
    title ="Lunar science: The Apollo Legacy",
    author = "Burnett, D. S.",
    journal = "Reviews of Geophysics",
    volume = "13",
    number = "3",
    pages = "13-34",
    month = "July",
    year = "1975",
    doi = "10.1029/RG013i003p00013",
    issn = "8755-1209",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141106-085710045",
    note = "Copyright © 1975 by the American Geophysical Union. \n\nI acknowledge years of profitable discussions with my Caltech colleagues, particularly G. J. Wasserburg, and with the members of the Lunar Sample Analysis Planning Team during Apollo 15, 16, and 17. This paper was prepared with financial support from NASA grant NAS 07 023 and with a tremendous effort on the part of Jeanne Grinols. Contribution 2582 of the Division of Geological and Planetary Sciences, California Institute of Technology.",
    revision_no = "10",
    abstract = "A general review of lunar science is presented, utilizing two themes: a summary of fundamental problems relating to the composition, structure, and history of the moon and a discussion of some surprising, unanticipated results obtained from Apollo lunar science. (1) The moon has a crust of approximately 60-km thickness, probably composed of feldspar-rich rocks. Such rocks are exposed at the surface in the light-colored lunar highlands. Many highlands rocks are complex impact breccias, perhaps produced by large basin-forming impacts. Most highlands rocks have ages of ∼3.9 × 10^9 yr; the record of igneous activity at older times is obscured by the intense bombardment. The impact rate decreased sharply at 3.8–3.9 × 10^9 yr ago. The impact basins were filled by flows of Fe- and, locally, Ti-rich volcanic rocks creating the dark mare regions and providing the strong visual color contrast of the moon, as viewed from earth. Crustal formation has produced enrichments in many elements, e.g., Ba, Sr, rare earths, and U, analogous to terrestrial crustal rocks. Compared with these elements, relatively volatile elements like Na, K, Rb, and Pb are highly depleted in the source regions for lunar surface rocks. These source regions were also separated from a metal phase, probably before being incorporated into the moon. The physical properties of the lunar mantle are compatible with mixtures of olvine and pyroxene, although Ca- and Al-rich compositions cannot be ruled out. Deeper regions, below ∼1000 km, are probably partially molten. (2) Lunar rocks cooled in the presence of a magnetic field very much stronger than the one that exists today, owing either to dynamo action in an ancient molten core or to an external magnetization of the moon. Lunar soil properties cannot be explained strictly by broken-up local rocks. Distant impacts throw in exotic material from other parts of the moon. About 1% of the soil appears to be of meteoritic origin. Vertical mixing by impacts is important; essentially all material sampled from lunar cores shows evidence of surface residence. The surface layers of lunar material exposed to space contain a chemical record of implanted solar material (rare gases, H) and constituents of a lunar atmosphere (^(40)Ar, Pb). Large isotopic fractionation effects for O, Si, S, and K are present. Physical properties of the surface layers are dominated by radiation damage effects. Lunar rocks have impact craters (≤1 cm) produced by microgram-sized interplanetary particles. The contemporary micrometeorite flux may be much higher than is indicated by the microcrater densities, indicating time variations in the flux. Particle track studies on the returned Surveyor camera filter first showed that the Fe nuclei were preferentially enhanced in solar flares.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/62057,
    title ="Fourth Lunar Science Conference",
    author = "Burnett, Donald and Silver, L.",
    journal = "Science",
    volume = "181",
    number = "4100",
    pages = "615-622",
    month = "August",
    year = "1973",
    doi = "10.1126/science.181.4100.615",
    issn = "0036-8075",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20151111-100013325",
    note = "© 1973 American Association for the Advancement of Science. \n\nThis article was prepared by the Lunar Sample Analysis Planning Team. Participating were P. Bell, Carnegie Institution Geophysical Laboratory, Washington, D.C.; A. Burlingame, University of California, Berkeley; D. Burnett and L. Silver, California Institute of Technology, Pasadena; S. Chang and D. Gault, NASA Ames Research Center, Moffett Field, California; P. Eberhardt, Universitat Bern, Bern, Switzerland; L. Haskin, University of Wisconsin, Madison; O. James, U.S. Geological Survey, Washington, D .C.; J. Papike, State University of New York, Stony Brook; G.Reed, Argonne National Laboratory, Argonne, Illinois; N. Toksiiz, Massachusetts Institute of Technology, Cambridge; and J . Wood, Smithsonian Astrophysical Observatory, Cambridge, Massachusetts. The manuscript was compiled by J. Wood.",
    revision_no = "10",
    abstract = "On 30 January 1973, the last sample containment bag from the last Apollo mission to the moon was logged into the processing cabinets of the Lunar Receiving Laboratory in Houston, Texas. The Apollo program, an undertaking that began as a demonstration of technological prowess and evolved into one of the greatest voyages of scientific exploration in our century, had drawn to a close.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/53104,
    title ="The depth distribution of hydrogen in lunar materials",
    author = "Leich, D. A. and Tombrello, T. A.",
    journal = "Earth and Planetary Science Letters",
    volume = "19",
    number = "3",
    pages = "305-314",
    month = "July",
    year = "1973",
    doi = "10.1016/0012-821X(73)90080-0",
    issn = "0012-821X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141222-133711484",
    note = "© 1973 Published by Elsevier B.V.\n\nReceived 22 March 1973;\nRevised version received 8 May 1973.\n\nSupported in part by the National Science Foundation [GP-28027].\n\nWe are grateful to Professors S Epstein, H P Taylor,\nJr and G J Wasserburg for the use of their facilities\nand for many helpful discussions. The Apollo 16\nPt foil was graciously supplied by R M Walker. A \nAlbee provided the chlorite standard. The lunar samples\nused in this work were allocated to Professor\nWasserburg under NASA contract NGL 05-002-188.",
    revision_no = "10",
    abstract = "A technique employing the resonant nuclear reaction ^1H(^(19)F, αγ) ^(16)O has been used to measure hydrogen concentration versus depth in selected coarse fine fragments from the Apollo 11 and Apollo 15 missions, and in glass coated surface chips from two Apollo 15 rocks. The highly variable hydrogen content in the coarse fine fragments is concentrated mainly in a layer extending from the surface to a depth of 2000 ± 500A˚. The hydrogen content of the surface region of the Apollo 15 rock chips is comparable to that of the coarse fine samples, but is concentrated mainly within a few hundred angstroms of the surface. The hydrogen depth distribution in a piece of platinum foil from the Apollo 16 Lunar surface Cosmic Ray Experiment was also measured in an attempt to place a limit on the flux of 10–40 keV protons associated with a solar flare event.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/62049,
    title ="Third Lunar Science Conference",
    author = "Burlingame, A. and Burnett, D.",
    journal = "Science",
    volume = "176",
    number = "4038",
    pages = "975-981",
    month = "June",
    year = "1972",
    doi = "10.1126/science.176.4038.975",
    issn = "0036-8075",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20151111-095216486",
    note = "© 1972 American Association for the Advancement of Science. \n\nThis article was prepared by the Lunar Sample Analysis Planning Team. Participating were A. Burlingame. University of California, Berkeley; D. Burnett, California Institute of Technology, Pasadena; B. Doe, U.S. Geological Survey, Denver; D. Gault, NASA Ames Research Center, S Moffett Field, California; L. Haskin and H. Schnoes, University of Wisconsin, Madison; D. Heymann, Rice University, Houston, Texas W. Melson, Smithsonian Institution, Washington, D.C.; J. Papike, State University of New York Stony Brook; R. Tilling, U.S. Geological Survey and NASA headquarters, Washington, D.C.; N. Toksoz, Massachusetts Institute of Technology Cambridge; and J. Wood, Smithsonian Astrophysical ObservatorY, Cambridge, Massachusetts. The manuscript was compiled by J. Wood. \n\nR. K. McConnell, Jr., and P. W. Gast, in a paper delivered at the Conference on Lunar Geophysics held at the Lunar Science Institute, Houston, Texas, 18 to 21 October 1971.",
    revision_no = "12",
    abstract = "Two years ago the first scientific investigations of returned lunar samples were reported at the Apollo 11 Lunar\nScience Conference (1). Samples from the first mission to the moon had been in the hands of investigators for 3\nmonths or less, and the picture of the  moon that emerged at that time was necessarily restricted in scope. We\nlearned that Tranquillity Base is underlain\nby basaltic rock that erupted onto\nthe mare surface 3.7 X 10^9 years ago,\nrock that is generally similar to terrestrial\nbasalts but with important differences:\ntitanium and other refractory\nelements are enhanced in abundance,\nsodium and other volatile elements are\ndepleted, and the water content and\noxidation potential o!f the lunar basalt\nlava are orders of magnitude lower\nthan those of analogous terrestrial lavas.\nThe existence of other types of rock\non the moon was only glimpsed, and\nthe structure and evolution of the moon\nremained a mystery.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/61950,
    title ="Formation Times of Meteorites and Lunar Samples",
    author = "Burnett, D. S.",
    journal = "Eos",
    volume = "52",
    number = "7",
    pages = "435-440",
    month = "July",
    year = "1971",
    doi = "10.1029/EO052i007pIU435",
    issn = "0096-3941",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20151106-130831738",
    note = "© 1971 American Geophysical Union.",
    revision_no = "8",
    abstract = "This article summarizes research since the last detailed reviews of meteorite ages by Anders [1963] and Reynolds [1967]. Only crystallization ages based on parent-daughter isotopic relationships resulting from the decay of naturally occurring radioactive nuclei will be discussed. The basic principles and techniques for age determinations are discussed in many of the papers cited and, along with summaries of scientific results, in several recent books [Dalrymple and Lanphere, 1969; Doe 1970; Hamilton, 1965; Schaeffer and Zahringer, 1966; Faul, 1966]. However, developments in the field have made some of the material in the books obsolete.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51428,
    title ="Isotopic composition of gadolinium and neutron-capture effects in some meteorites",
    author = "Eugster, O. and Tera, F.",
    journal = "Journal of Geophysical Research",
    volume = "75",
    number = "14",
    pages = "2753-2768",
    month = "May",
    year = "1970",
    doi = "10.1029/JB075i014p02753",
    issn = "0148-0227",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141107-102841930",
    note = "Copyright 1970 by the American Geophysical Union. \n\n(Received November 24, 1969; revised February 3, 1970.) \n\nWe wish to thank Hannelore and Uwe Derksen for their able technical assistance and John Huneke and Günther Lugmair for useful comments on the manuscript. We are 'grateful to our colleagues who supplied meteorite samples used in this work: Norton County, Pasamonte, Forest City, and Weekeroo Station were obtained from the Nininger Meteorite Collection at the Arizona State University through the aid of C. B. Moore. Copiapo was supplied by Drs. P. Pellas, J. Orcel and F. Kraut of the Paris Natural History Museum. \n\nThis work was supported by National Science Foundation grants GP 9433 and GP 9114.\n\nDivision of Geological Sciences Contribution No. 1697.",
    revision_no = "9",
    abstract = "The isotopic composition of Gd in one chondrite, two achondrites, and the silicate inclusions of two iron meteorites has been determined. When corrected for mass discrimination, Gd in all samples except the Norton County achondrite shows the same relative isotopic abundances as terrestrial Gd. These results set an upper limit of 3×10^(15) neutrons per cm^2 on a differential integrated thermal neutron irradiation of the earth and these meteorites. Neutron-capture effects are present in Gd extracted from the Norton County achondrite. These most probably have been produced by secondary neutrons during the exceptionally long cosmic ray exposure of this large stone meteorite. The isotopic anomalies correspond to an integrated thermal neutron flux of (6.3±0.9)×10^(15) neutrons per cm^2. The percent abundances of terrestrial Gd found in our work for Gd^(160), Gd^(158), Gd^(157), Gd^(156), Gd^(155), Gd^(154), and Gd^(152) are 21.863, 24.835, 15.652, 20.466, 14.800, 2.1809, and 0.2029, respectively. Because of the higher precision, these abundances should replace the currently accepted values.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/37018,
    title ="Ages, Irradiation History, and Chemical Composition of Lunar Rocks from the Sea of Tranquillity",
    author = "Albee, A. L. and Burnett, D. S.",
    journal = "Science",
    volume = "167",
    number = "3918",
    pages = "463-466",
    month = "January",
    year = "1970",
    
    issn = "0036-8075",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130220-113109469",
    note = "© 1970 American Association for the Advancement of Science.\n\n\nWe thank our fellow inmates Pai Young and Uwe Derksen for the sophisticated skill and knowledge they have brought to this study, without which this work would not have been\naccomplished. We also acknowledge the unstinting efforts of J. Brown, H. L. Derksen, L. llay, and T. Wen. This work was supported by NASA contract 64049.",
    revision_no = "11",
    abstract = "The ^(87)Rb-^(87)Sr internal isochrons for five rocks yield an age of 3.65±0.05 × 10^9 years which presumably dates the formation of the Sea of Tranquillity. Potassium-argon ages are consistent with this result. The soil has a model age of 4.5 × 10^9 years, which is best regarded as the time of initial differentiation of the lunar crust. A peculiar rock fragment from the soil gave a model age of 4.44 × 10^9 years. Relative abundances of alkalis do not suggest differential volatilization. The irradiation history of lunar rocks is inferred from isotopic measurements of gadolinium, vanadium, and cosmogenic rare gases. Spallation xenon spectra exhibit a high and variable 1^(31)Xe/^(126)Xe ratio. No evidence for ^(129)I was found. The isotopic composition of solar-wind xenon is distinct from that of the atmosphere and of the average for carbonaceous chondrites, but the krypton composition appears similar to average carbonaceous chondrite krypton. ",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51445,
    title ="Correlation between fission tracks and fission type xenon in meteoritic Whitlockite",
    author = "Wasserburg, G. J. and Huneke, J. C.",
    journal = "Journal of Geophysical Research",
    volume = "74",
    number = "17",
    pages = "4221-4232",
    month = "August",
    year = "1969",
    doi = "10.1029/JB074i017p04221",
    issn = "0148-0227",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141107-122112454",
    note = "Copyright 1969 by the American Geophysical Union. \n\n(Received April 23, 1969.) \n\nWe thank Mr. J. Brown for his competent and meticulous work in obtaining the whitlockite separate and in sample preparation. Frequent discussions with William A. Fowler have been both stimulating and thought provoking. We thank O. Eugster and David N. Schramm for useful comments on the manuscript. \n\nThis work was principally supported by grants from the National Science Foundation (GP-9433 and GP-9114). \n\nThis paper is to be included in a collection of reprints in memory of the late Craig M. Merrihue. \n\nContribution 1630 of the California Institute of Technology.",
    revision_no = "9",
    abstract = "Whitlockite from the St. Severin chondrite, previously shown to contain excess fission tracks, is here shown to have a large concentration of excess neutron-rich xenon isotopes. The concentration of excess heavy Xe in the whitlockite is about twenty-five times that calculated from the track density. An isotopic spectrum is deduced that is identical to the spectrum calculated previously for excess heavy xenon in the Pasamonte achondrite. These results uniquely associate this xenon spectrum with in situ fission in meteorites. Chemical arguments support the correlation of this with Pu^(244). Identification of the fissioning nucleus as Pu^(244) gives Pu^(244)/U^(238) ≈ 1/30. Neither ‘sudden’ nor ‘uniform’ nucleosynthetic models give consistent solutions for Pu^(244)/U^(238) and U^(235)/U^(238).",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/5260,
    title ="Correlation Between Fission Tracks and Fission-Type Xenon from an Extinct Radioactivity",
    author = "Wasserburg, G. J. and Huneke, J. C.",
    journal = "Physical Review Letters",
    volume = "22",
    number = "22",
    pages = "1198-1201",
    month = "June",
    year = "1969",
    
    issn = "0031-9007",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:WASprl69",
    note = "©1969 The American Physical Society \n\nReceived 24 April 1969 \n\nWe thank Mr. J. Brown for his competent and meticulous work in obtaining the whilockite separate and in sample preparation. Frequent discussions with W. A. Fowler have been both stimulating and thought provoking. This experiment was conceived when the authors became aware of the high density of tracks and urnaium found in whitlockite by Paul Pellas[21]. We thank O. Eugster for useful comments on the manuscript. \n\nWork supported by National Science Foundation Grants Nos. GP 9433 and 9114.",
    revision_no = "6",
    abstract = "Meteoritic whitlockite containing excess fission tracks has a large concentration of excess neutron-rich xenon isotopes which is 25 times that calculated from the track density. The isotopic spectrum is identical to that calculated previously for the Pasamonte achondrite. These results uniquely associate this spectrum with in situ fission. Identification of the fissioning nucleus as Pu244 gives Pu244/U238 ≅ 1/30 at the time of xenon retention. Neither \"sudden\" nor \"uniform\" nucleosynthetic models give consistent solutions for Pu244/U238 and U235/U238.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/37016,
    title ="^(87)Rb-^(87)Sr isochron and ^(40)K-^(40)Ar ages of the norton county achondrite",
    author = "Bogard, D. D. and Burnett, D. S.",
    journal = "Earth and Planetary Science Letters",
    volume = "3",
    
    pages = "179-189",
    month = "November",
    year = "1967",
    
    issn = "0012-821X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130220-104628650",
    note = "© 1967 Elsevier B.V. Received 14 November 1967. This paper is dedicated to Professor H. H. Nininger for his pioneer efforts in finding and collecting meteorites and making them available for scientific research. The samples used in this research were obtained from the Nininger Meteorite Collection at the Arizona State University through the aid of C. W. Moore. An additional sample of the Norton County\nMeteorite to was provided by W. Nichiporok. We gratefully\nacknowledge the assistance of T. Wen in the chemical an J mass spectrometric analyses. The electron microprobe data were obtained with the help of A. E. Bence and A. Chodos.\nThis research was supported by grants from the National Science Foundation, NSF GA-464 and NSF GP-5391 and the U.S. Atomic Energy Commission AEC (AT-04-3(427)).",
    revision_no = "16",
    abstract = "Analysis of seven different portions of Norton County yielded Rb/Sr ratios ranging from 0.15 to 2.3 and permitted the determination of an isochron with high precision. The Rb and Sr concentrations were found to be as low as ∼0.16 ppm. All of the data lie to within their experimental errors on a line in the Sr evolution diagram of slope 0.0654 ± 0.0014, and intercept 0.700 ± 0.002. This determines an age of 4.7 ± 0.1 × 10^9 yr for λ = 1.39 × 10^(−11) yr^(−1). ^(40)K^(40)Ar ages on samples containing 42, 53 and 107 ppm K gave ages of 4.2 – 4.5 × 10^9 yr which are compatible with the Rb-Sr age. The K appears to be concentrated in alkali feldspar grains of about 5–50 microns. The ^(87)Rb^(87)Sr age and primary ^(87)Sr/^(86)Sr value is of sufficient precision to permit the age resolution of meteoritic objects which were formed 0.3 × 10^9 yr apart. No evidence of element redistribution was found for Norton Country as indicated by the consistency of our Rb-Sr and K-Ar results.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/37004,
    title ="^(87)Rb-^(87)Sr ages of silicate inclusions in iron meteorites",
    author = "Burnett, D. S. and Wasserburg, G. J.",
    journal = "Earth and Planetary Science Letters",
    volume = "2",
    number = "5",
    pages = "397-408",
    month = "August",
    year = "1967",
    
    issn = "0012-821X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130220-074211638",
    note = "© 1967  Elsevier B.V. Received 19 June 1967. We wish to thank C. Frondel and U. Marvin of Harvard University, E. P. Henderson of the U.S. National Museum, V. Manson of the American Museum of Natural History and C. Moore of the Ninninger Meteorite Collection, for the meteorite samples used in this work. We thank Theodore Wen for invaluable assistance with the analytical work and L.P. Silver and P. Eberhardt for profitable discussions. This research was supported by grants from the National Science Foundation, NSF GA-464 and NSF GP-5391 and the U.S, Atomic Energy Commission AEC (AT-04-3(427)). ",
    revision_no = "10",
    abstract = "Rb-Sr measurements were made on silicate inclusions extracted from the iron meteorites Toluca, Odessa, Four Corners, Linwood, Pine River, Colomera and Weekeroo Station. Strontium isotopic analyses were made on samples as small as 24 ng. The typical Sr and Rb blanks were 2 × 10^(−9) g and 2 × 10^(−10) g, respectively. In certain cases it was possible to obtain relatively precise isochrons.\nWith the exception of Colomera, all of these samples gave ages compatible with 4.4 to 4.8 × 10^9 y. The Colomera data scatter widely and do not meet the requirements for defining a reliable age. None of the samples are compatible with an age of 6 × 10^9 y. The primary strontium observed or estimated for Toluca and Pine River agrees with that obtained from achondrites.\nIt is evident that extensive Rb-Sr isotopic studies may be made on a large number of rather typical iron meteorites.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/36860,
    title ="Evidence for the formation of an iron meteorite at 3.8 × 10^9 years",
    author = "Burnett, D. S. and Wasserburg, G. J.",
    journal = "Earth and Planetary Science Letters",
    volume = "2",
    number = "3",
    pages = "137-147",
    month = "May",
    year = "1967",
    
    issn = "0012-821X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20130212-075050629",
    note = "© 1967 Published by Elsevier B.V.\nReceived 1 May 1967.\nWe gratefully acknowledge the cooperation of\nDr. E. Olsen of the Chicago Natural History Museum\nand Drs. Orcel, Pellas, and Kraut of the\nParis Mus6e d'Histoire Naturelle in obtaining\nmeteorite samples. We were aided in the chemical\nand mass spectrometric analyses by Theodore\nWen, and benefited from discussions with\nDrs. L. T. Silver and P. Eberhardt.\nThis work was supported by grants from the\nNational Science Foundation, NSF GA-464 and\nNSF GP-5391, and the U.S. Atomic Energy Commission\nAEC (AT-04-3(427)).",
    revision_no = "11",
    abstract = "Rb Sr isotopic analyses were made on silicate inclusions from Kodaikanal, a brecciated fine octahedrite. Twelve analyses of different mineral fractions and separate inclusions were made. The silicates in this iron meteorite are highly enriched in alkalis and show ^(87)Sr/^(86)Sr ratios ranging up to 8.8. The samples lie on a well defined isochron on the Sr-Rb evolution diagram and indicate an age of 3.8 ± 0.1 × 10^9 y and an initial ^(87)Sr/^(86)Sr ratio between 0.69 and 0.73. These data provide unambiguous evidence for the ‘formation’ of younger solid objects in the solar system in a process which demands extensive chemical differentiation. This is evidence for an intermediate history for some meteoritic objects of a different sort than has been previously observed.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/5253,
    title ="Kinetic energy—mass distributions from the fission of nuclei lighter than radium",
    author = "Plasil, F. and Burnett, D. S.",
    journal = "Physical Review",
    volume = "142",
    number = "3",
    pages = "696-715",
    month = "February",
    year = "1966",
    
    issn = "0031-899X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:PLApr66",
    note = "©1966 The American Physical Society. \n\nReceived 19 August 1965. \n\nWe would like to thank Dr. J.R. Nix and Dr. W.J. Swiatecki for their guidance and collaboration in connection with the theoretical portions of this work. We also acknowledge very useful discussions with H.R. Bowman and Dr. E.L. Haines. We are further indebted to Dr. Haines for help during the early heavy-ion bombardments. We would like to thank D.J. O'Connell and his co-workers for preparing the targets used in these experiments, W.L. Hansen and his group for supplying us with the solid-state detectors and M. Nakamura for valuable help with electronic equipment, in particular with the multiparameter analyzers. We are grateful to Mrs. C.E. Rugge for writing the programs connected with the theoretical neutron dispersion calculations and to Dr. T. Sikkeland for permission to use his chamber during the heavy-ion bombardments. The help of Mrs. J. Phillips in preparing the manuscript is gratefully acknowledged.",
    revision_no = "5",
    abstract = "The distributions in masses and total kinetic energies of fission fragments from a number of elements ranging from erbium to bismuth have been measured. The nuclei undergoing fission were produced by bombarding a variety of targets with projectiles ranging from He4 to O16. The energies of coincident fission fragments were measured using solid-state counters. The energy data were transformed to give mass-total kinetic energy density-of-events distributions. These distributions were compared with those calculated from an approximate version of the liquid-drop model which applies to this region of elements. General agreement in the shapes and widths of the distributions was found, particularly in the cases which involved small angular momenta and small nuclear temperatures. The dependence of the widths of the experimental distributions on the nuclear temperature was found to differ from that predicted by the theory, but uncertainties in the evaluation of nuclear temperatures for the reactions investigated may be large. Analysis of these uncertainties indicated that they were not large enough to alone account for the discrepancy, although this analysis was subject to some error. Angular momentum effects were studied by using certain combinations of targets and projectiles to give the compound nucleus Os186 at the same excitation energy but with different angular momenta. The effect of increasing angular momentum was to broaden and change the shape of the experimental distributions.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/51472,
    title ="The relative isotopic abundance of K^(40) in terrestrial and meteoritic samples",
    author = "Burnett, D. S. and Lippolt, H. J.",
    journal = "Journal of Geophysical Research",
    volume = "71",
    number = "4",
    pages = "1249-1269",
    month = "February",
    year = "1966",
    doi = "10.1029/JZ071i004p01249",
    issn = "0148-0227",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20141107-164204989",
    note = "Copyright 1966 by the American Geophysical Union. \n\n(Manuscript received October 15, 1965.) \n\nWe wish to thank Professor R. E. Folinsbee, Professor C. Frondel, Walter Nichiporuk, and Professor L. T. Silver for meteorite samples used in this work. We wish to acknowledge especially the cooperation of Professor C. B. Moore and the Nininger Meteorite Collection in obtaining and discussing meteorite samples. We are grateful to Professors W. A. Fowler and L. T. Silver for valuable discussions. This work was supported in part by the Office of Naval Research [Nonr-220(47)], the National Aeronautics and Space Administration [NGR-05-002-028], the U.S. Atomic Energy Commission [AT(04-3)-427], and the National Science Foundation.",
    revision_no = "9",
    abstract = "Fowler, Greenstein, and Hoyle have proposed that the inner solar system was heavily irradiated during its formation. A consequence of this proposal is that sizable differences in meteoritic and terrestrial K^(41)/K^(40) ratios are possible if the fraction of material which was irradiated was different in the two cases. The isotopic composition of potassium was measured by mass spectrometry for nine stone meteorites, silicate from the Vaca Muerta mesosiderite and the Weekeroo Station iron meteorite, and four terrestrial samples. The measured K^(41)/K^(40) ratios were corrected by normalizing the measured K^(39)/K^(41) ratio to the Nier value of 13.47. This normalization procedure approximately cancels out any variations in the isotopic abundance except those due to nuclear processes. Measurements on enriched standards showed that any variations greater than 1% would certainly have been detected, and variations greater than ½% would probably have been detected with replicate analyses. Within these limits, no variations in the K^(40) abundance between the terrestrial and meteoritic samples could be found which could be ascribed to particle irradiation in the early history of the solar system. Small K^(40) enrichments were observed in Norton County, Weekeroo Station, and Vaca Muerta; however, these appear to have been produced during cosmic-ray irradiation by the Ca^(40)(n, p) reaction. The present results set relatively strong limitations on possible mechanisms for the formation of the earth and the meteorites if the idea of a large-scale irradiation in the early history of the solar system is to be retained. Independent of the model of Fowler et al., limits have been placed on any differential uniform irradiation. The implications of the present work on the K-Ar ages of stone and iron meteorites are discussed. The possibility that iron meteorites are considerably older than the solar system as a whole appears unlikely.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/62695,
    title ="Strontium-Rubidium Age of an Iron Meteorite",
    author = "Wasserburg, G. J. and Burnett, D. S.",
    journal = "Science",
    volume = "150",
    number = "3705",
    pages = "1814-1818",
    month = "December",
    year = "1965",
    doi = "10.1126/science.150.3705.1814",
    issn = "0036-8075",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:20151208-104231231",
    note = "© 1965 American Association for the Advancement of Science. \n\nReceived 29 October 1965. \n\nWe thank H. J. Lippolt for valuable discussion during the initial phases of this work, W. A. Fowler for provocative discussion and continuing interest, and Theodore Wen for careful analytical work. Supported by NSF and by contracts with the AEC [AT-04-3(427)] and ONR [Nonr-220(47)]. Contribution No. 1388 from California Institute of Technology.",
    revision_no = "11",
    abstract = "The isotopic compositions and concentrations of rubidium and strontium were determined in silicate nodules contained in Weekeroo Station meteorite, a brecciated coarse octahedrite. The strontium had a Sr^(87):Sr^(86) range from 0.729 to 0.768, showing considerable enrichment in Sr^(87) in comparison with achondrites. Data for six samples of nodules lie on a straight line on the Sr-Rb evolution diagram, with an initial Sr^(87):Sr^(86) ratio of 0.696 to 0.702; the slope is 0.0674, corresponding to an age of 4.7 x 10^9 years for λ = 1.39 x 10^(-11) year^(-1). These data agree with the previously assigned ages for the formation of stony meteorites and the earth; they support the conclusion that the major period of chemical and physical differentiation in the solar system occurred in a narrow interval at about this time. This result disagrees with the Ar^(40)-K^(40) ages of 5 to 13 x 10^9 years determined from other iron meteorites. A wide variety of isotopic-age investigations now seem experimentally feasible on iron meteorites that contain silicates.",
}
@article {CaltechAUTHORS_https://authors.library.caltech.edu/id/eprint/5259,
    title ="Fission Barrier of Thallium-201",
    author = "Burnett, Donald S. and Gatti, Raymond C.",
    journal = "Physical Review",
    volume = "134",
    number = "5B",
    pages = "B952-B963",
    month = "June",
    year = "1964",
    
    issn = "0031-899X",
    
    url = "https://resolver.caltech.edu/CaltechAUTHORS:BURpr64",
    note = "©1964 The American Physical Society \n\nReceived 23 December 1963 \n\nThe work of adopting the least squares fitting program to the theoretical functions, data fittings proper, and all activities directly concerned with the computers were carried out by Claudette Rugge. Her outstnading contribution to this work deserves the highest recognition. \n\nWe are grateful to Bernard G. Harvey and the staff of the 88-in. cyclotron for help and cooperation with the experimental work. We also acknowledge the valuable assistance of Jean Rees and Joan Phillips in preparing this manuscript in helping with the scanning. We are grateful to Ray Nix and John Huizenga for very valuable discussions. We appreciate the support given by the General Electric Company in enabling one of us (Price) to take part in these experiments. \n\nThis work was done under the auspices of the U.S. Atomic Energy Commission.",
    revision_no = "5",
    abstract = "A new method involving the detection of fission fragments in mica has been applied to the measurement of the fission cross section of the compound nucleus Tl201 produced by bombardments of Au197 with helium ions. These data have been interpreted in terms of an expression for the ratio of fission to neutron-emission probabilities similar to those used conventionally, but modified to include the effect of quantum-mechanical barrier penetrability. In this way a height of 22.5±1.5 MeV was found for the fission barrier of Tl201 and a lower limit on the width could be established. The above value of the barrier, when interpreted on the basis of the liquid-drop theory, leads to an accurate determination of the ratio of the electrostatic to the surface energy of nuclei. This serves to establish the constant of proportionality between the \"fissionability parameter\" x and the value of Z2/A as follows: x=(Z2/A)/(48.4±0.5). This measured barrier height, when added to the ground-state mass of Tl201, gives a saddle-point mass of this nucleus equal to 200.9949±0.0015 mass units (carbon scale).",
}