Thesis (M.S. in Chemistry)--University of California, Berkeley, Jan. 1958. / Also issued as UCRL 8020. Includes bibliographical references (leaves 31-33).

Thesis (M.S. in Chemistry)--University of California, Berkeley, Novmber 1956. / Includes bibliographical references (leaves 34-35).

Thesis (Ph. D. in Chemistry)--University of California, Berkeley, June 1956. / Includes bibliographical references (leaves 71-74).

Thesis (Ph. D. in Chemistry)--University of California, Berkeley, September 1960. / "UCRL-9083." TID-4500 (15th Ed.). Includes bibliographical references (leaves 144-151).

Thesis--University of California, Berkeley, November 1956. / "Contract no. W-7405-eng-48." Bibliography: leaves 114-121.

Thesis (Ph. D.)--Oregon State University, 2011. / Printout. Includes bibliographical references (leaves 91-95). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Foram medidos os \"yields\" de eletrofissão do 236 ANTPOT u e 238 ANTPOT u na faixa de 5 a 30 MeV, bem como as distribuições angulares dos fragmentos de eletrofissão, utilizando o feixe de elétrons do Acelerador Linear do Instituto de Física da Universidade de São Paulo. É apresentado um formalismo para análise das distribuições angulares dos fragmentos de foto e eletrofissão, a partir do qual é estudada a competição entre os canais de quadrupolo na fotofissão do 238 ANTPOT u. Desenvolveu-se um novo método de análise para a obtenção de contribuições multipolares , diferentes de El, no processo da fotofissão, que permite obter o \"yield\" integrado dos multipolos adicionais a partir da análise simultânea da foto e eletrofissão, mais o formalismo dos fótons virtuais em DWBA. Através do \"unfolding\" das secções de choque dos multipolos adicionais foram obtidas ressonâncias gigantes de E2 para 236 ANTPOT u e 238 ANTPOT. U, com picos em (10,7 ± 0,2) MeV e (9,9 ± 0,2) MeV, e larguras de (7,8 ± 0,2) MeV e (8,7 ± 0,2) MeV, respectivamente . As posições das ressonâncias E2 estão em razoável acordo com as previsões de Bohr e Mottelson: Ep = 60. A POT -1/3 MeV. As larguras são compatíveis com um possível \"splitting\" triplo das ressonâncias. Foram mostradas evidências quanto a uma mistura de Ml na faixa 6-7 MeV. / Measurements of electrofission yields of 236u and 238u were perfomed in the energy range of 5 to 30 MeV, as well as angular distribution of electrofission fragments using the electron beam of the Linear Accelerator of the Physics Institute of the University of São Paulo. A formalism for the analysis of angular distribution of photo and electrofission fragments is presented, from which a competition between the quadrupole channels in the photo fission of 238u is studied. A new method of analysis to obtain the multipole contribution, other than El, in the process of photofission was developed, which allows the obtainment of the integrated yield on the additional multipoles, from the simultaneous analysis of photo and electrofission using the formalism of virtual photons in OWBA. Through the unfolding of the additional multipoles cross sections the E2 giant resonances were obtained for the 236u and 238u, presenting peaks at (10.7 ± 0.2) MeV and (9.9 ± 0.2) MeV, and widths of (7.8 ± 0.2) MeV and (8.7±0.2) MeV, respectively. The positions of these E2 resonances are in reasonable agreement with the predictions of Bohr and Mottelson: Ep = 60 A -1/3 MeV. The width are compatible with a possible triple splitting of the resonances. Evidences of a Ml mixture were shown in the energy range of 6 to 7 MeV.

An experimental study of the pion-induced fission, ⁶Li (π⁺, ³He) ³He, has been performed at TRIUMF using 60, 80 and 100 MeV pions. Angular distributions for this reaction at these energies, along with the energy dependence at fixed center-of-mass angles, are presented. Two theoretical models of this reaction predict widely differing angular and energy dependences. Prior to this experiment, the available data on the ⁶Li (π⁺, ³He) ³He reaction (and its inverse, ³He (³He, π⁺) ⁶Li) were insufficient to determine which of the two calculations better represent the reaction. The new data presented here have thoroughly tested these two models in this energy regime and have determined their suitability in their descriptions of the ⁶Li (π⁺, ³He) ³He reaction. From these data (and from results previously published for the inverse ³He (³He, π⁺) ⁶Li reaction at an equivalent pion energy of 15.4 MeV), the differential cross-sections were fit to an orthogonal Legendre polynomial series at each energy. These fits allowed the total cross-section to be extracted as a function of pion energy between 15.4 and 100 MeV. The total cross-section, and the center-of-mass differential cross-section at a fixed center-of-mass angle, were found to exhibit an exponential decrease with pion energy over this range. The coefficients of these polynomial fits also clearly show the growing importance of higher-order partial-waves with increasing energy. Finally, a phenomenological search for systematics in the world data of the ⁶Li (π⁺, ³He) ³He and ³He (³He, π⁺) ⁶Li reactions was made. This attempt was successful in finding a dependence of the reaction upon the spin-state of the exit channel which is similar to that previously seen in (p, π⁺) experimental data. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

SOFIA (Studies On FIssion with Aladin) est un programme expérimental innovant qui a pour objectif la mesure de plusieurs observables de la fission nucléaire : les taux de production isotopiques des fragments de fission, l'énergie cinétique totale des fragments, et la multiplicité des neutrons prompts. Ces informations sont obtenues pour une large variété d'actinides et de pré-actinides. Le recours à la cinématique inverse (le système fissionnant est le faisceau et non pas la cible) est le seul moyen d'identifier les fragments à la fois en charge et en masse. Le travail de doctorat présenté dans cette thèse porte sur l'expérience menée en Octobre 2014 et dédiée à la mesure de la fission de ² ³ ⁶ U induite par excitation coulombienne, soit l'analogue de la fission de ² ³⁵U induite par neutron.Les expériences SOFIA ont lieu à GSI (Darmstadt, Allemagne), la seule installation au monde capable de délivrer un faisceau d'uranium ² ³⁸ de 1 GeV par nucléon. Ce faisceau primaire subit une première fragmentation, dont les produits sont sélectionnés par le FRS (FRagment Separator) afin de former un faisceau secondaire du noyau d'intérêt, en l'occurrence ² ³ ⁶ U, qui est guidé vers l'expérience SOFIA où sa fission est déclenchée.Certains noyaux proches de ² ³ ⁶ U sont également transmis par le FRS : il est donc nécessaire de procéder à l'identification en masse et en charge du système fissionnant, puis d'identifier les deux fragments de fission. Dans les deux cas, l'identification, réalisée événement par événement, repose sur la mesure simultanée de la perte d'énergie dans un gaz, de la rigidité magnétique et du temps de vol. Seules les fissions induites par excitation coulombiennes sont pertinentes : la contribution des réactions nucléaires à la production des fragments doit donc être mesurée et soustraite.L'analyse présentée dans ce document inclut l'identification du faisceau secondaire en masse et en charge, l'identification en charge des fragments de fission, l'estimation de la contribution des réactions nucléaires, et finalement les taux de production des éléments obtenus dans la fission de ² ³ ⁶ U. Ces résultats sont comparés à ceux d'autres mesures réalisées sur SOFIA, et à des résultats antérieurs obtenus par d'autres techniques. / SOFIA (Studies On FIssion with Aladin) is an innovative experimental program which aims to measure several fission observables — the isotopic fission yields, the total kinetic energy of the fragments and the prompt neutron multiplicity, for a wide range of actinides and pre-actinides. The use of inverse kinematics (the fissioning system is the beam instead of the target) is the only way to fully identify fragments in charge and mass. The PhD work presented in this thesis concerns the experiment conducted in October 2014, and is focused on the Coulomb-induced fission of ² ³ ⁶ U, which can be regarded as the analog of the neutron-induced fission of ² ³⁵U.The SOFIA experiments take place in GSI (Darmstadt, Germany) because it is the sole facility in the world which delivers a beam of ² ³⁸U at 1 AGeV. This beam is fragmented and the products are selected by the FRS (FRagment separator) in order to deliver a secondary beam of nuclei of interest - ² ³ ⁶ U in our case, which is then guided to the SOFIA setup where its fission is triggered.Since some nuclides with close atomic and mass numbers to ² ³ ⁶ U are also transmitted by the FRS, it is necessary to identify the fissioning system from the secondary beam first, and then identify both the associated fission fragments. All identifications are performed event by event on the basis of measurements of the energy loss, the magnetic rigidity and the time of flight. Since we are only interested in the Coulomb-induced fission of ² ³ ⁶ U, the contribution of fragmentation fissions on the nuclear charge distribution of fission fragments has to be suppressed.The analysis in this paper involves the isotopic identification of the fissioning system, the nuclear charge identification of the fission fragments, the estimation of the nuclear contribution, and the extraction of the elemental fission yield. The results are then compared to other measurements performed with the SOFIA setup, as well as previous results obtained by other techniques.