Neste trabalho as diversas propostas de \'\'Trajetórias Coletivas\" apresentadas na literatura foram derivadas a partir de uma análise local das equações dinâmicas de Hartree Fock Dependente do Tempo. Estas propostas foram comparadas e condições de validade obtidas para hamiltonianas semiclássicas que tem apenas termos de 2ª ordem nos momentos. Uma análise cuidadosa da parametrização de Determinantes de Slater permitiu- nos explorar as características geométricas da teoria de Hartree-Fock Dependente do tempo e construir as trajetórias num formalismo covariante. Esta análise foi aplicada a um modelo esquemático de três níveis SU(3). / In this work, the many proposals of Collective Paths\" that have appeared in literature, were derived through a local analysis of the Time Dependent Hartree Fock dynamics. Those proposals were compared and validity conditions obtained for Semiclassical Hamiltonians which have only quadratic terms in momenta. A careful analysis of the parametrization of Slater Determinants allowed us to exploit the geometrical features of the Time Dependent Hartree Fock Theory and construct the Paths in a covariant way. The analysis was applied to a three level model (SU(3)).

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3759. Adviser: Roy A. Axford. Includes bibliographical references (leaves 309-311) Available on microfilm from Pro Quest Information and Learning.

Several comprehensive but time consuming neutronic codes are available for performing nuclear reactor and fuel cycle evaluations. In addition, simple models utilizing collision probability theory are used to perform similar tasks with reasonable accuracy. However, the current collision probability theory treats the heterogeneous reactor configurations with a two region unit cell model. This model does not address several important reactor parameters including spatial self-shielding effects and simultaneous use of different reactor fuels within a reactor core. This dissertation studies the fidelity of expanding the collision probability theory to address the stated shortcomings through analyzing two problems. Problem 1 analyzes the effects of self-shielding. The cylindrical fuel region is divided into several sub-regions and an overall equivalent escape probability from the entire fuel region is developed based on the identified neutron transmission and escape probabilities within each fuel sub-region. The multiplication factor and radioisotopic inventory results based on modified V:BUDS (Visualize: Burnup, Depletion, Spectrum) code are in good agreement with benchmark scenarios for a reactor unit cell. The accurate multiplication factor calculation allows more accurate studies on the maximum fuel burnup and radionuclide inventories of interest in nuclear non-proliferation studies. Problem 2 analyzes the effects of simultaneous use of different fuels within a fuel lattice where the zero neutron leakage assumption across the unit cell boundaries is not valid. The developed methodology expands capabilities of the collision probability theory to a supercell model that allows existence of two different fuels. The radioisotopic inventory results for different fuels obtained from the modified V:BUDS code are in excellent agreement with the benchmark problems. These accurate results may be used in general fuel cycle and transmutation studies within power reactors.

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<p>The nearly oblate deformed Au nuclei show rotational bands built on multi quasiparticle excitations [Bou89, Bou92, Gue03, Gue01, Ven92]. Several of these bands are built on rotationally aligned high-j proton and neutron excitations. In many cases bands consisting of two or three signature partner E2 sequences are observed. For some fo these bands signature inversion is found and this feature gives a great challenge to the theoretical models. In this study the researcher performed TRS and CSM calculations for all high-j rotational bands in the p186-194s Au nuclei aiming to predict the signature splitting and inversion phemomena, alignments, gains in alignments, gains in alignment and band crossing frequencies observed.</p>

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The angular anisotropy, $ omega$, of individual fission products produced from the $ sp{238} rm U( sp{12}$C, f) 119.9 MeV incident heavy-ion induced fission reaction, was modelled in terms of the angular momentum, l, conferred upon the intermediate nucleus. Evidence of incomplete momentum transfer led to a model treating fission products as being the result of two fission inducing processes: complete fusion resulting in compound nucleus formation, and an $ alpha$-transfer incomplete fusion process. The average angular anisotropies for each of the two processes were calculated to be, $ omega sb{ rm CF}$ = 2.57, and $ omega sb alpha$ = 1.71, respectively, which fit well to the experimental data. A new method was developed to estimate the total kinetic energy release of heavy-ion fission events leading to individual fission products from the above reaction. The average total $ langle$E$ sb{ rm k}{ rangle} approx 195$ MeV calculated using the new method is consistent with other experimental data, and with theories regarding heavy-ion induced fission.

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