Stars with a core mass greater than about 30 M\u2299 become dynamically unstable due to electron-positron pair production when their central temperature reaches 1.5-2.0 x 109 0K. The collapse and subsequent explosion of stars with core masses of 45, 52, and 60 M\u2299 is calculated. The range of the final velocity of expansion (3,400 \u2013 8,500 km/sec) and of the mass ejected (1 \u2013 40 M\u2299) is comparable to that observed for type II supernovae.
\r\nAn implicit scheme of hydrodynamic difference equations (stable for large time steps) used for the calculation of the evolution is described.
\r\nFor fast evolution the turbulence caused by convective instability does not produce the zero entropy gradient and perfect mixing found for slower evolution. A dynamical model of the convection is derived from the equations of motion and then incorporated into the difference equations.
\r\n", "doi": "10.7907/TJZ7-D968", "publication_date": "1967", "thesis_type": "phd", "thesis_year": "1967" }, { "id": "thesis:6946", "collection": "thesis", "collection_id": "6946", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04192012-090557368", "primary_object_url": { "basename": "Helliwell_tm_1963.pdf", "content": "final", "filesize": 28928687, "license": "other", "mime_type": "application/pdf", "url": "/6946/1/Helliwell_tm_1963.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "The Nodal Boundary Condition Method : Wave Functions and Transition Probabilities for Atoms with Two Valence Electrons", "author": [ { "family_name": "Helliwell", "given_name": "Thomas McCalfree", "clpid": "Helliwell-Thomas-McCalfree" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "A method is presented for computing valence atomic wave functions and transition probabilities. This method, called the \"nodal boundary condition method\", is a modified self-consistent-field approach to eliminate the need for calculating wave functions for the core electrons, wave functions, and transition probabilities for several atoms and ions having two valence electrons.
\r\n\r\nVarious other approaches to the problem of calculating atomic wave functions are reviewed, so that the assumptions and approximations of the nodal boundary condition method may be placed in perspective. The results of the present calculations are compared in detail with previous results whenever possible applications and extensions of the method are briefly discussed.
", "doi": "10.7907/MGYT-HF26", "publication_date": "1963", "thesis_type": "phd", "thesis_year": "1963" }, { "id": "thesis:7257", "collection": "thesis", "collection_id": "7257", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:11062012-103119433", "primary_object_url": { "basename": "Levine_ph_1963.pdf", "content": "final", "filesize": 66988501, "license": "other", "mime_type": "application/pdf", "url": "/7257/1/Levine_ph_1963.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Phase Space Formulation of the Quantum Many-Body Problem", "author": [ { "family_name": "Levine", "given_name": "Paul Hersh", "clpid": "Levine-Paul-Hersh" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" }, { "family_name": "von Roos", "given_name": "Oldwig", "clpid": "von-Roos-O" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "By means of a quantum mechanical phase space distribution function\r\nintroduced by von Roos, the Schroedinger equation for a non-relativistic\r\nsystem of N identical particles with scalar interactions is transformed\r\ninto a quantum mechanical generalization of the Liouville equation,\r\nthereby formulating the problem in terms of a generalized density in\r\nphase space, a quantity of primary interest in most treatments of the\r\ncorresponding classical system (or \"plasma\"). This transformation permits\r\na parallel development of the theories of classical and quantum plasmas\r\nand thus allows the quantum many-body problem to be discussed virtually\r\ncompletely in classical terms. In particular, a kinetic theory of\r\nquantum plasmas is obtained by deriving the quantum analogue of the BBGKY\r\nhierarchy, and applying thereto approximation techniques similar to those\r\nof Rostocker and Rosenbluth, and Bogoliubov. The point of departure from\r\nsimilar previous studies based on the Wigner distribution function is that\r\nthe proper exchange symmetry can be tractably introduced into the formalism.
\r\n\r\nAttention is first focused on the Hartree and Hartree-Fock approximations,\r\nin which case the quantum BBGKY system reduces to a simple quantum\r\ngeneralization of the Vlasov equation. This equation is used to study\r\nthe response of spatially homogeneous systems to weak external forces,\r\nand the associated problems of plasmon and spin-wave excitations. It is\r\nalso used to derive the quantum and exchange corrected equations of\r\ninviscid hydrodynamical transport which are then applied to the problem\r\nof sound propagation in the degenerate electron gas.
\r\n\r\nThe second part of the study is concerned with the theory of the\r\nmany-electron atom in the Hartree and Hartree-Fock approximations.\r\nThe relevant quantum Vlasov equations lead naturally to a \"statistical\"\r\ntheory of the atom which reduces to the Thomas-Fermi-Amaldi and Thomas Fermi\r\nmodels (respectively) as \u0127 \u2192 0. For \u0127 \u2260 0, the quantum and\r\nexchange corrections to these models are simultaneously generated. The\r\nquantum hydrodynamical theory developed earlier is used to determine\r\nthe influence of these corrections on the boundary conditions of the\r\nmodel, and a theory of the compressed atom is consequently obtained.\r\nConsidered in somewhat less detail are the effects of non-zero temperature,\r\nnet orbital angular momentum, relativity and correlations, as well as\r\ntime dependent processes.
\r\n\r\nThe final part deals with the problem of the degenerate electron\r\ngas with a uniform neutralizing background. Going beyond the Hartree-Fock approximation, the pair correlation functions for particles with\r\n\"parallel\" and \"anti-parallel\" spin are obtained by neglecting three particle\r\ncorrelations. From these functions, a quantum-mechanical collision\r\nintegral is derived which differs from that obtained by Silin\r\nand Guernsey and conjectured by Wyld and Pines in that dynamical exchange\r\neffects are included. Also obtained from the pair correlation function\r\nis an expression for the \"correlation energy\" which reduces in the high\r\ndensity limit to the result of Gell-Mann and Brueckner. At intermediate\r\ndensities an additional term appears in the energy due to the screening\r\nof the exchange interaction by the dielectric properties of the medium.\r\nIt is evaluated in the high density limit and found to be -0.151 r_s ln r_s\r\nRyd/electron in marked disagreement with the corresponding value obtained\r\nby DuBois.
\r\n", "doi": "10.7907/2JYR-A438", "publication_date": "1963", "thesis_type": "phd", "thesis_year": "1963" }, { "id": "thesis:6608", "collection": "thesis", "collection_id": "6608", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:08192011-115123033", "primary_object_url": { "basename": "Engelbrecht_ca_1962.pdf", "content": "final", "filesize": 4144798, "license": "other", "mime_type": "application/pdf", "url": "/6608/1/Engelbrecht_ca_1962.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Photoproduction of Neutral Pions in Complex Nuclei", "author": [ { "family_name": "Engelbrecht", "given_name": "Christian Albertus", "clpid": "Engelbrecht-Christian-Albertus" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "The photoproduction of neutral pions from complex nuclei is expressed in terms of the photoproduction from single nucleons by means of the direct interaction model and the impulse approximation. A summation over all final states of the nucleus is performed by means of a closure approximation.
\r\n\r\nWithin the framework of the independent particle model of the nucleus, the nuclear matrix elements are evaluated exactly for closed shell nuclei, the final results being expressed in terms of the nucleon density and the two-particle correlation functions in the nuclear ground state. For quantitative purposes the correlation functions are calculated both in the ease of a Fermi gas and for harmonic oscillator wave functions.
\r\n\r\nThe differential cross section is decomposed into an elastic part, which leaves the nucleus in its ground state, and an inelastic part. The elastic cross section has a coherent peak close to the forward direction. The inelastic part is suppressed at small angles because of the contribution from the correlation functions, which is a manifestation of the exclusion principle.
\r\n\r\nThe interactions of the produced pion with the nucleus are included by means of the optical model. Numerical integrations are performed using an approximate wave function for the pion.
\r\n\r\nNeutral pions can also be produced by the interaction with the electrostatic field of the nucleus. This process is related to the lifetime of the pion for decay into two photons.
\r\n\r\nWhen compared with the available experimental results, the theoretically predicted cross sections seem to be too low. Possible reasons for this discrepancy are discussed.
", "doi": "10.7907/W82V-D913", "publication_date": "1962", "thesis_type": "phd", "thesis_year": "1962" }, { "id": "thesis:6571", "collection": "thesis", "collection_id": "6571", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:08032011-143635344", "primary_object_url": { "basename": "Miller_cr_1962.pdf", "content": "final", "filesize": 12140878, "license": "other", "mime_type": "application/pdf", "url": "/6571/1/Miller_cr_1962.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "On the Orientation of Dust Grains in Interstellar Space", "author": [ { "family_name": "Miller", "given_name": "Charles Robert", "clpid": "Miller-Charles-Robert" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" }, { "family_name": "Mathews", "given_name": "Jon", "clpid": "Mathews-J" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "The observed polarization of starlight is regarded as being due to absorption by interstellar dust. A mechanism for alignment of the dust grains, due to Davis and Greenstein, is analyzed. A dissipative torque, due to paramagnetic relaxation in the grains, tends to line up a spinning dust grain in the interstellar magnetic field. This aligning torque is opposed by the randomizing effect of collisions with interstellar hydrogen. The aim of this paper is to find the distribution of orientations which results. The analysis is carried out through use of the Fokker-Planck equation. The solution is carried to completion for the case of small magnetic fields and nearly spherical dust grains, and the resulting polarization parameter is found. The spectrum of relaxation times due to the collisions is also found.
\r\n", "doi": "10.7907/9A8Q-2G27", "publication_date": "1962", "thesis_type": "phd", "thesis_year": "1962" }, { "id": "thesis:4717", "collection": "thesis", "collection_id": "4717", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-12022004-155343", "primary_object_url": { "basename": "Duck_im_1961.pdf", "content": "final", "filesize": 3539999, "license": "other", "mime_type": "application/pdf", "url": "/4717/1/Duck_im_1961.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Muon Capture in the Shell Model", "author": [ { "family_name": "Duck", "given_name": "Ian Morley", "clpid": "Duck-Ian-Morley" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" }, { "family_name": "Mathews", "given_name": "Jon", "clpid": "Mathews-J" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nAn effective weak interaction Hamiltonian due to Primakoff has been used in conjunction with the shell model of the nucleus to predict [...] meson capture rates to the bound states of [...], [...] and [...]. All three of these nuclei have a slow inverse [...] decay which should permit detection of a capture by an experiment which is easier than that necessary when the inverse [...] decay is fast. The [...] and [...] capture rates are predictable with sufficient confidence to constitute a test for the presence of the induced pseudoscalar interaction in [...] capture, but are not sufficiently sensitive to the presence of the conserved vector current in the weak interaction to decide on its existence. The [...] predictions are interesting from the point of view of nuclear structure, in that they are an analogue of \"allowed but unfavored\" transitions in [...] decay theory, and the capture rate is reduced due to the different space symmetries of the states involved. Central values of the predicted capture rates to bound states are, in [...]; [...]; and in [...].", "doi": "10.7907/VWWY-B590", "publication_date": "1961", "thesis_type": "phd", "thesis_year": "1961" }, { "id": "thesis:458", "collection": "thesis", "collection_id": "458", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-02022006-093244", "primary_object_url": { "basename": "Kohler_d_1959.pdf", "content": "final", "filesize": 4241492, "license": "other", "mime_type": "application/pdf", "url": "/458/1/Kohler_d_1959.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Observations on the Lifetimes of the 3.37-Mev 2\u207a State of Be\u00b9\u2070 and of the 6.14-Mev 3\u207b State of O\u00b9\u2076", "author": [ { "family_name": "Kohler", "given_name": "Donald Alvin", "clpid": "Kohler-Donald-Alvin" } ], "thesis_advisor": [ { "family_name": "Barnes", "given_name": "Charles A.", "clpid": "Barnes-C-A" }, { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" }, { "family_name": "Fowler", "given_name": "William A.", "clpid": "Fowler-W-A" }, { "family_name": "Lauritsen", "given_name": "Thomas", "clpid": "Lauritsen-T" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nAn upper limit for the lifetime of the 3.37-Mev 2+ state of Be10 has been established by use of a Doppler shift technique. Be10 nuclei were produced by the Be9 (d,p)Be10 reaction and those protons leaving the Be10 in its 3.37-Mev excited state were used to select [...] rays emitted by Be10* nuclei having a well defined recoil velocity. The energy of the [...] rays emitted by these nuclei was determined by scintillation spectroscopy. The experiment was designed to look for a possible difference between the [...]-ray Doppler shifts produced when the recoil nuclei were stopped in a metal foil and when the nuclei were allowed to recoil into vacuum. A small statistically insignificant difference in shift was observed which allowed only an upper limit of about 2.0 x 10(-13) seconds for the half-life [mean life: [...] seconds] to be inferred. This limit to the mean life is compared with theoretical estimates of the lifetime based on different nuclear models.\r\n\r\nThe lifetime of the 6.14-Mev 3- state of O16 has been measured by means of a recoil technique. The spatial distribution of decays of recoiling O16 nuclei, produced by the F19[...]O16+ reaction, was studied with a highly collimated [...]-ray detector. Comparison with the corresponding results obtained when the [...] nuclei were stopped at the target surface by an evaporated metallic layer provided a convenient means of determining the lifetime. A value for this half-life of (8.6 +/- 4.0) x 10(-12) seconds [mean life: [...] = (1.2 +/- 0.6) x 10(-12) seconds] has been found, consistent with previously established limits. The measured value of the mean life is compared with the theoretical values of the lifetime according to various nuclear models.", "doi": "10.7907/ERYR-RC89", "publication_date": "1959", "thesis_type": "phd", "thesis_year": "1959" }, { "id": "thesis:2041", "collection": "thesis", "collection_id": "2041", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05252004-105255", "primary_object_url": { "basename": "Zachariasen_f_1956.pdf", "content": "final", "filesize": 2211574, "license": "other", "mime_type": "application/pdf", "url": "/2041/1/Zachariasen_f_1956.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Photodisintegration of the Deuteron", "author": [ { "family_name": "Zachariasen", "given_name": "Fredrik", "clpid": "Zachariasen-Fredrik" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "The Chew meson theory has been applied in an attempt to explain the observed resonance occurring in the photodisintegration of the deuteron at an energy of about 250 Mev. The resonance is interpreted as being due to the rescattering of a virtual photoproduced meson in the J = 3/2, T = 3/2 state from one of the two nucleons, the meson being finally absorbed. The impulse approximation is used to describe the scattering. Results are obtained for the total cross section as a function of energy in qualitative agreement with experiment, but though an asymmetry in the angular distribution is found, it does not give a different cross section at 0[degrees] and 180[degrees] as seems to be required by the data.", "doi": "10.7907/KKDZ-ET45", "publication_date": "1956", "thesis_type": "phd", "thesis_year": "1956" }, { "id": "thesis:2617", "collection": "thesis", "collection_id": "2617", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06162004-135505", "primary_object_url": { "basename": "Mozer_fs_1956.pdf", "content": "final", "filesize": 5605863, "license": "other", "mime_type": "application/pdf", "url": "/2617/1/Mozer_fs_1956.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Experimental Determination and Theoretical Analysis of the Elastic Scattering of Protons by Beryllium", "author": [ { "family_name": "Mozer", "given_name": "Forrest S.", "clpid": "Mozer-Forrest-S" } ], "thesis_advisor": [ { "family_name": "Fowler", "given_name": "William A.", "clpid": "Fowler-W-A" }, { "family_name": "Lauritsen", "given_name": "Charles Christian", "clpid": "Lauritsen-C-C" }, { "family_name": "Lauritsen", "given_name": "Thomas", "clpid": "Lauritsen-T" }, { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nFifteen angular distributions and three excitation curves for the reaction [...] have been run in the energy region between 200-3000 kev, Measurements of [...] and [...] were made at 333 kev and near 470 kev. This data has been analyzed and fitted in terms of the following states in [...]; an s-wave [...] state near 330 kev; a p-wave [...] state near 980 kev; an s-wave [...] state near 998 kev; a p-wave [...] state near 1084 kev; and an s-wave [...] state near 1330 kev.", "doi": "10.7907/84KG-8D29", "publication_date": "1956", "thesis_type": "phd", "thesis_year": "1956" }, { "id": "thesis:348", "collection": "thesis", "collection_id": "348", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-01262004-103546", "primary_object_url": { "basename": "Mills_wr_1955.pdf", "content": "final", "filesize": 3366078, "license": "other", "mime_type": "application/pdf", "url": "/348/1/Mills_wr_1955.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Absolute Measurements of Internal Conversion Coefficients", "author": [ { "family_name": "Mills", "given_name": "William Raymond", "clpid": "Mills-William-Raymond" } ], "thesis_advisor": [ { "family_name": "Lauritsen", "given_name": "Thomas", "clpid": "Lauritsen-T" }, { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" }, { "family_name": "Fowler", "given_name": "William A.", "clpid": "Fowler-W-A" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "NOTE: text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nA magnetic lens spectrometer has been used to measure electron yields from the internal conversion of certain nuclear gamma rays. Auxiliary experiments have been performed to determine the effective solid angle of the spectrometer. A technique which has previously proven to be successful has been tested and employed in the measurement of gamma-ray yields by means of a scintillation counter. The combination of conversion electron and gamma yield measurements constitutes an experimental determination of an internal conversion coefficient, and by comparison with theory it is possible to make gamma-ray multipole order assignments.\r\n\r\nBi207 decays to an isomeric state of Pb207 at 1.63 Mev which emits two successive gamma rays with energies 1.06 and 0.57 Mev, the decay proceeding through a level at 0.57 Mev. Internal conversion lines from both transitions have been observed previously. We have measured the conversion coefficients and found the 1.06-Mev line to be M4 with E2 indicated for the 0.57-Mev line.\r\n\r\nUsing the reaction [...] we have observed internal conversion lines from the decay of the first two excited states of F19. The transition energies are 109.1 ? 1.0 and 196.8 ? 1.5 kev as determined from the conversion lines. The experimental internal conversion coefficients indicate the following multipole order assignments, in agreement with other data: 109 kev, E1; 197 kev, E2.\r\n\r\nThe first excited state of Na23 at 440 kev has been produced in [...]. We have measured the conversion coefficient of the 440-kev transition and assign it either E1 or M1, the experimental uncertainties preventing a definite assignment. Results of other work are cited which indicate M1 is correct.\r\n\r\nWe have attempted to measure the conversion coefficient of the 470-kev line in Na24 produced in [...]. The low intensity of the line, however, permits only the statement that it is of multipole order less than [...].\r\n\r\nThe lens spectrometer has also been employed to survey the low energy gamma ray spectrum resulting from [...] and [...]. The electron spectra from external photoelectric converters suggest lines at 118 ? 5 and 275 ? 15 kev from the first reaction and 196.5 ? 4 kev from the latter.", "doi": "10.7907/E32D-W195", "publication_date": "1955", "thesis_type": "phd", "thesis_year": "1955" }, { "id": "thesis:264", "collection": "thesis", "collection_id": "264", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-01222004-092833", "primary_object_url": { "basename": "Speisman_g_1955.pdf", "content": "final", "filesize": 1457377, "license": "other", "mime_type": "application/pdf", "url": "/264/1/Speisman_g_1955.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "The Neutron-Proton Mass Difference", "author": [ { "family_name": "Speisman", "given_name": "Gerald", "clpid": "Speisman-Gerald" } ], "thesis_advisor": [ { "family_name": "Feynman", "given_name": "Richard Phillips", "clpid": "Feynman-R-P" }, { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nIt is proposed than the neutron-proton and [...] mass differences are produced by the electromagnetic field. In order to make the quantum electrodynamic mass corrections convergent, it is necessary to cut off the photon propagation function and the anomalous moment interaction of the neutron and proton for high virtual proton masses. The cutoff masses required to give the observed mass differences are of the order of the proton mass. These cutoffs are in agreement with the relatively small changes nucleon moments appear to undergo when nucleons form nuclei, and with experiments on electron-neutron and electron-proton scattering. A classical interpretation of the neutron-proton mass difference is discussed. A justification of the quantum electrodynamic calculation based on quantum field theory is also given.", "doi": "10.7907/SSHW-9C33", "publication_date": "1955", "thesis_type": "phd", "thesis_year": "1955" }, { "id": "thesis:365", "collection": "thesis", "collection_id": "365", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-01272004-091647", "primary_object_url": { "basename": "Woodruff_to_1955.pdf", "content": "final", "filesize": 4263623, "license": "other", "mime_type": "application/pdf", "url": "/365/1/Woodruff_to_1955.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "On the Orthogonalized Plane Wave Method for Calculating Energy Eigenvalues in a Periodic Potential", "author": [ { "family_name": "Woodruff", "given_name": "Truman Owen", "clpid": "Woodruff-Truman-Owen" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" }, { "family_name": "Feynman", "given_name": "Richard Phillips", "clpid": "Feynman-R-P" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "The orthogonalized plane wave OPW method is used in the first step towards determination of self-consistent solutions of the Hartree-Fock equations (with Slater's free-electron simplification of the exchange terms) for electrons in a diamond-type crystal. For illustrative purposes, the techniques developed are applied to the determination of energy eigenvalues of the valence and lowest conduction states with zero wave vector in silicon crystal. The initial crystal potential is computed from the charge distribution obtained by placing the atoms forming the crystal on the points of the appropriate space lattice. The atomic charge distributions are determined from simple orthogonalized Slater functions, which can be easily constructed for all atoms, rather than from Hartree or Hartree-Fock atomic functions. A procedure for determining sufficiently good approximations to the wave functions and energy eigenvalues for the core electrons in the initial crystal potential is given. The importance for the convergence and accuracy of the OPW method of using core wave functions which are eigenfunctions of the same operator used to determine the valence and excited states is emphasized. The secular determinant of the OPW method is factored by using appropriate linear combinations of orthogonalized plane waves in the trial function for the valence and excited states. In this connection a detailed exposition is given of a method for obtaining explicit representation matrices for the group of the wave vector, which can then be used to construct basis functions for these representations from sets of orthogonalized plane waves.", "doi": "10.7907/4BC1-0895", "publication_date": "1955", "thesis_type": "phd", "thesis_year": "1955" }, { "id": "thesis:43", "collection": "thesis", "collection_id": "43", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-01072004-090642", "primary_object_url": { "basename": "Kameny_sl_1955.pdf", "content": "final", "filesize": 4391977, "license": "other", "mime_type": "application/pdf", "url": "/43/1/Kameny_sl_1955.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "The \u03b1-Particle model of O\u00b9\u2076", "author": [ { "family_name": "Kameny", "given_name": "Stanley Leonard", "clpid": "Kameny-Stanley-Leonard" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nThe [alpha]-Particle model is re-derived and used to calculate the energy levels of O16, extending the work of Dennison to include all levels up to 15 Mev.\r\n\r\nWave functions for low lying levels are used to compute the lifetimes of the first four excited levels of O16.\r\n\r\nIn addition, the model is applied to furnish core wave functions for a partially-excited-core shell model of O17. The lifetime of the 870 Kev level and the electric quadrupole and magnetic moments of the ground state are computed.\r\n\r\nThe energy level predictions are found to be in good agreement with experiment, but the lifetime predictions are only fair. The O17 model can provide quantitative agreement with the lifetime only.\r\n\r\nThe evidence favoring either of the two identification schemes proposed by Dennison is not conclusive.", "doi": "10.7907/3044-7176", "publication_date": "1955", "thesis_type": "phd", "thesis_year": "1955" }, { "id": "thesis:45", "collection": "thesis", "collection_id": "45", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-01072004-095620", "primary_object_url": { "basename": "Karzas_wj_1955.pdf", "content": "final", "filesize": 3369389, "license": "other", "mime_type": "application/pdf", "url": "/45/1/Karzas_wj_1955.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "The Effects of Atomic Electrons on Nuclear Radiation", "author": [ { "family_name": "Karzas", "given_name": "William James", "clpid": "Karzas-William-James" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" }, { "family_name": "Feynman", "given_name": "Richard Phillips", "clpid": "Feynman-R-P" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "NOTE:Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nThe effects of the atomic electrons on nuclear gamma emission are considered. It is found that the electrons, excited by the nuclear electrostatic field, can emit gamma rays coherently with the nucleus and thus add to the observed intensity of radiation. The correction is computed for K electrons, for electric dipole and quadrupole radiation, and is found to be small, of the order of a few per cent, for energies equal to the K binding energy. It drops rapidly with increasing energy, varying inversely as the square of the gamma ray energy. The Z-dependence of the effect is essentially Z[superscript negative 1]. For gamma ray energies corresponding to electron transitions between bound levels large resonances may occur, but they are of narrow width and their observation would be fortuitous.", "doi": "10.7907/P9P1-C330", "publication_date": "1955", "thesis_type": "phd", "thesis_year": "1955" }, { "id": "thesis:78", "collection": "thesis", "collection_id": "78", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-01092004-102615", "primary_object_url": { "basename": "Liberman_da_1955.pdf", "content": "final", "filesize": 2641619, "license": "other", "mime_type": "application/pdf", "url": "/78/1/Liberman_da_1955.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "17.63 and 18.14 Mev States in Be\u2078", "author": [ { "family_name": "Liberman", "given_name": "David Arthur", "clpid": "Liberman-David-Arthur" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nThe experimental data relating to the 17.63 and 18,14 Mev states in Be8 is analyzed. It is shown that all available measurements are consistent with the assumption that both states have [...]. Since these states are obtained by bombarding [...] with protons, they must be .formed principally by p-wave protons. Ordinarily [...] terms would be expected in angular distributions for reactions involving these states, but they are not observed. From this it is concluded that a certain value of the channel spin ratio [...] is required. It is then shown that this value may be obtained on the assumption of an independent particle model with either jj or LS coupling. The particle and radiation widths are computed for these states using both LS and jj coupling schemes, and the results are found to be in order-of-magnitude agreement with experiment.", "doi": "10.7907/GFQP-E623", "publication_date": "1955", "thesis_type": "phd", "thesis_year": "1955" }, { "id": "thesis:1688", "collection": "thesis", "collection_id": "1688", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05092003-080704", "primary_object_url": { "basename": "Reynolds_hk_1953.pdf", "content": "final", "filesize": 7752571, "license": "other", "mime_type": "application/pdf", "url": "/1688/1/Reynolds_hk_1953.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "The Proton Stopping Cross Section of Gases at Low Energies", "author": [ { "family_name": "Reynolds", "given_name": "Harlan Kendall", "clpid": "Reynolds-Harlan-Kendall" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nProton stopping cross sections for gases and vapors were measured in the energy range 30 to 600 kev. A beam of protons was passed through a chamber with thin aluminum end walls containing the gas or vapor to be measured. The energy of the beam was measured before and after passing through the chamber and with and without the gas in the beam in order to measure the energy loss in the foils and in the gas. The beam was accelerated by an electrostatic generator, and the beam energies measured by an electrostatic analyzer and magnetic spectrometer.\r\n\r\nThe substances measured were air, H[subscript 2], He, N[subscript 2], O[subscript 2], Ne, A, Kr, Xe, H[subscript 2]O, CO[subscript 2], CH[subscript 4], C[subscript 2]H[subscript 2], C[subscript 2]H[subscript 4], C[subscript 6]H[subscript 6], NH[subscript 3], NO, and N[subscript 2]O. Bragg's rule was tested by comparison of NH[subscript 3] with N[subscript 2]/2 + 3H[subscript 2]/2, NO with N[subscript 2]/2 + O[subscript 2]/2 etc., for H[subscript 2]O, NH[subscript 3], NO, and N[subscript 2]O, and found to be valid above 150 kev, except for NO. On the assumption of Bragg's rule, the stopping cross section of carbon was calculated from the data on the hydrocarbons, CO[subscript 2], and oxygen and hydrogen. The results were consistent for energies above 100 kev. The mean excitation potentials calculated from the measured stopping cross sections are: Oxygen, I = 103[...]5 ev; nitrogen, I = 89.5[...]4 ev; carbon, I = 7.24[...]3 ev; and helium, I = 32.8[...]1.5 ev.", "doi": "10.7907/XGRY-HH72", "publication_date": "1953", "thesis_type": "phd", "thesis_year": "1953" }, { "id": "thesis:10568", "collection": "thesis", "collection_id": "10568", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:11212017-144140524", "type": "thesis", "title": "I. Retardation Corrections in the Helium Atom. II. Self Energy of an Electron in a Magnetic Field", "author": [ { "family_name": "Robbins", "given_name": "Howard Murray", "clpid": "Robbins-Howard-Murray" } ], "thesis_advisor": [ { "family_name": "Feynman", "given_name": "Richard Phillips", "clpid": "Feynman-R-P" }, { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "Part I.
\r\n\r\nAn analysis is made of the errors which arise\r\nfor absolute levels and fine structure separations\r\nfrom the use, for the interaction of two electrons,\r\nof the nonretarded Breit expression instead of the\r\ntrue retarded interaction. The effects on the fine\r\nstructure turn out to be too small for observation.\r\nThe correction to the ground state energy may\r\nbecome observable if the experimental accuracy is\r\nincreased. This is probably not the case for any \r\nexcited level.
\r\n\r\nPart II.
\r\n\r\nThe exact propagation function for a Dirac\r\nelectron in an arbitrarily intense magnetic field\r\nis derived in closed form as a parametric integral.\r\nUsing the exact relativistic wave functions and\r\nthe exact of order e2, due to the emission and \r\nreabsorption in closed form as double parametric \r\nintegrals. These integrals are shown to possess\r\nan asymptotic expansion in the small parameter H/m2.\r\nThis expansion is not a pure power series but involves\r\nalso terms of the form Hkln(m2/H). The terms\r\nof order H agrees with the known correction to the \r\nmagnetic moment. The terms of order H2\r\nand Hkln(m2/H) are exhibited\r\nand discussed.
", "doi": "10.7907/0VR6-PP86", "publication_date": "1952", "thesis_type": "phd", "thesis_year": "1952" }, { "id": "thesis:32", "collection": "thesis", "collection_id": "32", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-01052005-143146", "primary_object_url": { "basename": "Inonu_ei_1952.pdf", "content": "final", "filesize": 3951256, "license": "other", "mime_type": "application/pdf", "url": "/32/1/Inonu_ei_1952.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Interpretation of Large Ionization Bursts Observed at High Altitudes in High Pressure Chambers Under Thick Shields", "author": [ { "family_name": "\u0130n\u00f6n\u00fc", "given_name": "Erdal Ismet", "clpid": "\u0130n\u00f6n\u00fc-Erdal-Ismet" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "NOTE: Text not renderable in plain ASCII is indicated by [...]. Abstract is included in .pdf document.\r\n\r\nAn attempt is made to explain the ionization bursts containing 400 - 1600 particles observed at high altitudes in high pressure chambers heavily shielded with lead, in terms of short-lived neutral mesons produced by primary protons colliding with shield nuclei; neutral mesons instantly decay into photons which initiate electron cascades in the shield resulting in an ionization burst inside the chamber. The primary interaction is treated by means of a simple model for multiple meson production which assumes constant cross section, complete inelasticity and constant multiplicity throughout the energy region [...] ev; 1/3 of the primary energy is assumed to go into neutral mesons.\r\n\r\nThe contribution of the soft component of high energy air showers is estimated and found to be negligible at all altitudes. An analysis of burst data obtained by Neher and Biehl at three altitudes (307 gm, 616 gm, 1030 gm) then shows that the majority of high altitude bursts can be explained by neutral mesons produced in the primary encounter; but not a negligible fraction must be attributed to secondary collisions. From the data of Neher-Biehl and Fahy mean free paths of 185 [plus or minus] 20 gm in air and 355 [plus or minus] 55 gm in lead are deduced.\r\n", "doi": "10.7907/4NYG-0E88", "publication_date": "1952", "thesis_type": "phd", "thesis_year": "1952" }, { "id": "thesis:16302", "collection": "thesis", "collection_id": "16302", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:02232024-173017112", "primary_object_url": { "basename": "Day_RB_1951.pdf", "content": "final", "filesize": 21193530, "license": "other", "mime_type": "application/pdf", "url": "/16302/1/Day_RB_1951.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Angular Distributions of Some \u03b3-rays Produced in Nuclear Reactions", "author": [ { "family_name": "Day", "given_name": "Robert Briggs", "clpid": "Day-Robert-Briggs" } ], "thesis_advisor": [ { "family_name": "Fowler", "given_name": "William A.", "clpid": "Fowler-W-A" }, { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "Measurement of the angular distributions of they-rays produced\r\nin nuclear reactions promises to be a fruitful method in helping to\r\ndetermine the spins and parities of the nuclear states involved. The\r\nmethods and apparatus for doing this for proton reactions on light\r\nnuclei are described. Results are given for the following reactions:\r\nF19(p,\u03b1\u03b3)O16 at various resonances between 850 and 1400 kev,\r\nC12(p,\u03b3)N13 at the 1696 kev resonance, and C13(p,\u03b3)N14 at the 1754\r\nkev resonance. A short account is given of the principles involved\r\nin the calculation of angular distributions. This is followed by a\r\ndiscussion of the experimental results in terms of the spins and\r\nparities of the states. For the fluorine reaction this has already\r\nbeen done by Chao. The C12(p,\u03b3)N13 resonance seems to be due to a\r\ncompound nucleus with spin 3/2 and even parity. For the C13(p,\u03b3)N14\r\nresonance the theory does not permit a definite assignment to be\r\nmade on the basis of this experiment.", "doi": "10.7907/mfsw-2m02", "publication_date": "1951", "thesis_type": "phd", "thesis_year": "1951" }, { "id": "thesis:10515", "collection": "thesis", "collection_id": "10515", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10132017-101145132", "primary_object_url": { "basename": "Helstrom_CW_1951.pdf", "content": "final", "filesize": 25772713, "license": "other", "mime_type": "application/pdf", "url": "/10515/1/Helstrom_CW_1951.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Production and Annihilation of Antiprotons", "author": [ { "family_name": "Helstrom", "given_name": "Carl Wilhelm", "clpid": "Helstrom-Carl-Wilhelm" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "If protons and neutrons are Dirac particles, as one \r\nusually assumes, the corresponding antiparticles should ex\u00adist, \r\nbut these have never been observed. The coupling of \r\nnucleons with the meson field offers processes by which\r\nthese particles could be created in energetic collisions be\u00adtween \r\nnucleons and mesons or other nucleons. In this thesis \r\nthe pseudoscalar meson theory is used to calculate cross-sec\u00adtions \r\nfor the production of antiprotons in such collision processes. \r\nThese are applied to estimate the numbers of antiprotons to be \r\nexpected from the interaction of cosmic\u00ad ray particles with the \r\nnucleons of the atmosphere. It is found that meson production is \r\nabout 60 times more frequent than antinucleon production for the \r\ncomplete primary cosmic\u00ad ray spectrum, but that antinucleon production \r\nis of compar\u00adable probability with meson production for energies \r\ngreater than about 1011 e.v. Cross-sections are also \r\ncalculated for the annihilation of antiprotons in collisions \r\nwith protons and neutrons, with emission of mesons.\r\n", "doi": "10.7907/RCCV-Z308", "publication_date": "1951", "thesis_type": "phd", "thesis_year": "1951" }, { "id": "thesis:10474", "collection": "thesis", "collection_id": "10474", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10022017-101440348", "primary_object_url": { "basename": "Ruderman_MA_1951.pdf", "content": "final", "filesize": 28807600, "license": "other", "mime_type": "application/pdf", "url": "/10474/1/Ruderman_MA_1951.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "I. Electron Decay of the \u03c0-Meson. II. A Non-Linear Field Theory", "author": [ { "family_name": "Ruderman", "given_name": "Malvin Avram", "clpid": "Ruderman-Malvin-Avram" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" }, { "family_name": "Finkelstein", "given_name": "Robert J.", "clpid": "Finkelstein-Robert-J" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "Part I.
\r\n\r\nA \u03c0-meson decays into \u00b5-meson and neutrino at least 1000 times faster than\r\ninto an electron and a neutrino. After summarizing the difficulties in\r\nassuming that electrons or \u00b5-mesons interact with nucleons through the\r\nintermediary of the \u03c0-meson, the decay of the \u03c0 is discussed for the symmetric\r\ncoupling scheme in which electrons and \u00b5-mesons interact directly with\r\nnucleons. Selection rules rigorously forbid this decay for the most choices of\r\nthe \u03c0-meson field and the form of nuclear \u03b2-decay. For the very special\r\ncase of pseudoscalar meson and pseudovector \u03b2-decay (with arbitrary mixtures\r\nof scalar, vector and tensor) the decay rate for \u03c0 \u2192 (\u00b5,v) proceeds 104\r\ntimes as fast as \u03c0 \u2192 (\u00b5,v) and 10+3 as fast as \u03c0 \u2192 (photon, e, v).\r\nThis result is independent of perturbation theory. Agreement with the\r\nobserved lifetime can be obtained if the divergent integral is cut off at \r\nthe nucleon Compton wavelength.
\r\n\r\n\r\nPart II.
\r\n\r\nA unitary theory of particles is investigated, mostly on the classical level.\r\nThe Dirac and the Klein-Gordon equations are augmented\r\nby simple non-linear terms. Interpreted as wave equations for\r\nclassical fields they contain a much richer variety of solutions than\r\nthe customary linear theories. Particles, instead of having independent \r\nexistences as singularities, appear only as intense localized regions of\r\nstrong field. Solutions of the field equations are subject to the\r\nboundary condition that the fields be regular everywhere and that all\r\nobservable integrals be finite. For simple angular and temporal\r\ndependence the wave equation reduces to a set of ordinary differential\r\nequations. The boundary condition leads to a non-linear eigenvalue\r\nproblem whose solutions are systematically described in the phase plane.\r\nNumerical solutions are found for some typical cases. The masses of the\r\nparticles are positive; the number carrying unit charge is small. The\r\nscalar field variables can be interpreted in terms of operators according to\r\nthe usual commutation rules, but the particles are unstable when perturbed\r\nby quantum fluctuations. The application of anti-commutation rules to the \r\nspinor fields has no classical limit. The lack of satisfactory recipe for\r\nquantizing classical spinor fields makes the interpretation of the particle-like\r\nsolutions obscure.
", "doi": "10.7907/XK5P-ZD23", "publication_date": "1951", "thesis_type": "phd", "thesis_year": "1951" }, { "id": "thesis:10506", "collection": "thesis", "collection_id": "10506", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10112017-143307471", "primary_object_url": { "basename": "Woodbury_EJ_1951.pdf", "content": "final", "filesize": 17786405, "license": "other", "mime_type": "application/pdf", "url": "/10506/1/Woodbury_EJ_1951.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Capture Cross Section of C\u00b9\u00b3 for Low Energy Protons", "author": [ { "family_name": "Woodbury", "given_name": "Eric John", "clpid": "Woodbury-Eric-John" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "In order to measure the capture cross section of C13 at the\r\nlowest possible energy a scintillation detector in conjunction with\r\na high current ion source was developed. Because of heat dissipation\r\nproblems the ion source was pulsed and suitable electronic circuitry\r\nwas developed to take advantage of the peak currents available.\r\nWith this equipment it was found possible to obtain proton currents\r\nof one milliampere and a detection efficiency of eight percent.
\r\n\r\n\r\nAt 128 kilovolts the capture cross section is,
\r\n\r\n\u03c3 = 5.0 \u00b1 1.0 x 10-33 cm2
\r\n\r\n\r\nOf the resulting radiation approximately eighty percent is 8 Mev in\r\nenergy while the remaining is either a two or three step cascade\r\nwith gamma ray energies between two and four million volts of energy.
\r\n\r\nIn the equation,
\r\n\r\n\u03c3 = a/E e-b/E 1/2
\r\n\r\n\r\nb = 5.96 Mev1/2, and a = 10-2 Mev barn.
", "doi": "10.7907/9KQX-4335", "publication_date": "1951", "thesis_type": "phd", "thesis_year": "1951" }, { "id": "thesis:4293", "collection": "thesis", "collection_id": "4293", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-10282008-150916", "primary_object_url": { "basename": "O'Reilly_jd_1950.pdf", "content": "final", "filesize": 3436850, "license": "other", "mime_type": "application/pdf", "url": "/4293/1/O'Reilly_jd_1950.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "A Study of the Physical and Chemical Composition of Homogenous and Inhomogenous Models of the Sun", "author": [ { "family_name": "O'Reilly", "given_name": "James Donald", "clpid": "O'Reilly-James-Donald" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "In part I a radiative envelope, convective core model of the sun has been constructed on the assumption that the radiative opacity is due entirely to a Russell Mixture of heavy elements. The effect of scattering opacity is taken into account. Following the method of Schwarzschild and using the latest available data on the cross-section of the N[superscript 14] reaction, an estimate of the central temperature and composition of the sun has been made. It is found that the central temperature is approximately 17.5x10[superscript 6] \u00b0K, and that hydrogen, helium and heavy element abundances are .66, .31 and .03 respectively. A comparison is made with the results obtained from other recent investigations, and with the results of spectroscopic analysis of the solar atmosphere.\r\n\r\nIn part II the requirements of stability, energy generation and age of the sun are used to construct models of the sun in which the mean molecular weight of the envelope differs from that of the core. The physical and chemical properties of three such models are listed. A comparison with the results of spectroscopic analysis is made, and the conclusion is drawn that the latter are more in accord with the assumption of chemical homogeneity in the sun. A note is appended upon the results of a recent similar investigation by Ledoux.\r\n", "doi": "10.7907/13JF-3147", "publication_date": "1950", "thesis_type": "phd", "thesis_year": "1950" }, { "id": "thesis:17419", "collection": "thesis", "collection_id": "17419", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06072025-085830795", "primary_object_url": { "basename": "Cohen_ER_1949.pdf", "content": "final", "filesize": 34621625, "license": "other", "mime_type": "application/pdf", "url": "/17419/1/Cohen_ER_1949.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Angular Distributions in the Elastic Scattering of Protons by Light Nuclei. Analysis of the Reactions Li\u2077(pp)Li\u2077 and Be\u2079(pp)Be\u2079", "author": [ { "family_name": "Cohen", "given_name": "Emanuel Richard", "clpid": "Cohen-Emanuel-Richard" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "Use has been made of the Clebsch-Gordon series\r\nto evaluate the matrix elements involved in the onelevel\r\ndispersion model for the elastic scattering of\r\nprotons by light nuclei. The results have been used\r\nto describe the resonances at 440 kev and 1024 kev\r\nin the scattering of protons by lithium and the resonances\r\nat 988 and 1077 kev in beryllium. The 440\r\nkev lithium resonance seems to be definitely due to\r\nincident p-waves forming a compound state of Be8\r\nwith J = 1. The 1024 kev lithium resonance is tentatively\r\nidentified as due to s-wave forming a state\r\nwith J = 1, but more complete experimental data is\r\nnecessary before a definite assignment can be made.\r\nThe 988 kev beryllium resonance is ascribed to a\r\nlevel with J = 2 in B10 formed by incident a-wave\r\nprotons and the observed \u03b3-radiation is therefore\r\nelectric dipole. The narrow resonance at 1077 has\r\nbeen ascribed to incident d-wave and J = 0.
\r\n\r\nThe agreement of these assignments with other\r\nexperimental data is discussed.
", "doi": "10.7907/pemf-k490", "publication_date": "1949", "thesis_type": "phd", "thesis_year": "1949" }, { "id": "thesis:17362", "collection": "thesis", "collection_id": "17362", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06022025-152056180", "primary_object_url": { "basename": "Latter_R_1949.pdf", "content": "final", "filesize": 21873492, "license": "other", "mime_type": "application/pdf", "url": "/17362/1/Latter_R_1949.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "A Study of the Two-Meson Hypothesis", "author": [ { "family_name": "Latter", "given_name": "Richard", "clpid": "Latter-Richard" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "An attempt was made to obtain some indication theoretically\r\nas to the tensor character of the heavy and the light me sons\r\nobserved in cosmic rays. For this purpose the two-meson\r\nhypothesis of Bethe and Marshak was accepted. The heavy\r\nmeson which interacts with nucleons was assumed to be either\r\na scalar, a vector, or a pseudoscalar field in agreement\r\nwith nuclear force theories. The light meson was assumed to\r\nbe either a scalar, a pseudoscalar, or a spin \u00bd field in\r\nagreement with the evidence on meson burst production. The\r\nassociated secondary neutral particle was assumed to have\r\nthe same tensor character as the light meson. Conservation\r\nof spin and statistics limited consideration to seven mixed\r\nfields. For each of these fields the decaytime of the heavy\r\nmeson into the light meson and the lifetime of the light\r\nmeson for nuclear capture was computed. Using the most\r\nrecent values of the masses of the heavy and light mesons,\r\nthe decaytime of the heavy meson is \u03c4(scalar \u2192 spin \u00bd)~\r\n1.22x10-8sec., \u03c4(pseudoscalar~spin \u00bd)~1.94x10-9sec.,\r\n\u03c4(vector~spin \u00bd)~1.88x10-8sec., t(vector \u2192 pseudoscalar or\r\nscalar)~6.31x10-7sec., ~(scalar \u2192 pseudoscalar or scalar)~\r\n1.97x10-8sec.. These values are to be compared with the\r\nexperimental value of 10-8sec. In view of the zero mass of\r\nthe neutral secondary particle which makes it possible to\r\nidentify it with a neutrino and the ease of nuclear production\r\nof the heavy meson, the indication is that the heavy and light\r\nmesons are scalar and spin \u00bd fields, respectively.", "doi": "10.7907/yypa-vk52", "publication_date": "1949", "thesis_type": "phd", "thesis_year": "1949" }, { "id": "thesis:7243", "collection": "thesis", "collection_id": "7243", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10222012-141705031", "type": "thesis", "title": "A Study of the Altitude Dependence of the Large Cosmic-Ray Showers", "author": [ { "family_name": "Mills", "given_name": "Mark Muir", "clpid": "Mills-Mark-Muir" } ], "thesis_advisor": [ { "family_name": "Christy", "given_name": "Robert F.", "clpid": "Christy-R-F" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "Assuming primary electrons, the theoretical variation of\r\nshower counting rate with altitude has been computed and a comparison\r\nmade with the observations of Kraybill. Expressed as\r\nthe ratio to sea level, the observed counting rate has a maximum\r\nof 63 as compared to 24 for the theoretical curve. The observed\r\nmaximum is near 27,000 feet while the computed maximum\r\nis at 22,000 feet. Approximations in the calculation and observational\r\nuncertainties may make this difference in the elevations\r\nof the maxima spurious. The approximations are such as to\r\ngive too low a theoretical counting rate, but an estimate of the \r\nmagnitude seems to leave the theoretical maximum counting rate\r\ntoo small by a factor of 1.5 to 2. A computation based upon a\r\nmechanism for the multiple production of secondaries by primary\r\nprotons, which has been proposed by Lewis, Oppenheimer and Wouthuysen,\r\nwould probably lead to better agreement with the observations.
\r\n\r\nThe zenith angle distribution of showers detected by Kraybill\u2019s\r\ncounters at 30,000 feet has been computed and compared\r\nwith one determined by Mr. E.W. Cowan from cloud chamber measurements. The theoretical distribution is twice as broad as the observed\r\none. The angular distribution inferred from the altitude\r\ndependence observed by Kraybill is in much better agreement with\r\nthe theoretical than with the cloud chamber distribution. The\r\ndiscrepancy of the cloud chamber observations may arise from the\r\nfact that it was only possible to assign a direction to the tracks\r\nin 20 to 30 per cent of the photographs.
\r\n", "doi": "10.7907/3HVB-B176", "publication_date": "1948", "thesis_type": "phd", "thesis_year": "1948" } ]