Thesis (Ph. D.)--Florida State University, 2006. / Advisors: Vasken Hagopian, Sharon Hagopian, Florida State University, College of Arts and Sciences, Dept. of Physics. Title and description from dissertation home page (viewed Sept. 15, 2005). Document formatted into pages; contains xiv, 155 pages. Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago, Dept. of Physics, December 2000. / Includes bibliographical references. Also available on the Internet.

Made available in DSpace on 2014-10-09T12:51:43Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:34Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:51:43Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:34Z (GMT). No. of bitstreams: 0 / Medidas das secções de choque de fotonêutrons do 9Be, 13C e 17O foram obtidas no intervalo de energia entre 1,6 e 10,8 MeV, utilizando radiação gama de alta resolução em energia (3 a 21 eV) produzida na captura de nêutrons térmicos por 21 materiais alvo, quando posicionados no interior de um canal tangencial, junto ao núcleo do reator de pesquisa IEAR1 (5 MW) do IPEN/CNEN-SP. As amostras foram irradiadas no interior de um sistema detector de nêutrons “Long Counter”, de geometria 4π, a 520,5 cm de distância do alvo de captura. O fluxo de raios gama foi determinado por meio da análise do espectro gama obtido fazendo uso de um detector de estado sólido do tipo Ge(Li) (EG&G ORTEC, 25 cm3, 5%), previamente calibrado com raios gama de captura produzidos por uma amostra padrão de nitrogênio (Melamina). A secção de choque de fotonêutron foi medida para o espectro de raios gama de captura de cada alvo (secção de choque composta). Uma metodologia de inversão de matrizes para a resolução de problemas inverso discretos foi utilizada para a deconvolução do conjunto de valores experimentais da secção de choque composta, com a finalidade de obter a secção de choque em valores específicos de energia de excitação (energia das linhas gama principais dos alvos de captura). As secções de choque obtidas, nas energias das linhas gama principais de todos os alvos, foram comparadas com as medidas realizadas por outros autores utilizando diferentes fontes de radiação gama. Uma boa concordância foi observada entre os resultados experimentais deste trabalho com as relatados na literatura. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

No description available.

Made available in DSpace on 2014-10-09T12:36:14Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:20Z (GMT). No. of bitstreams: 1 03765.pdf: 4268943 bytes, checksum: 1eabaa58f9bf24d34593d59bf89ff6ca (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:36:14Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:20Z (GMT). No. of bitstreams: 1 03765.pdf: 4268943 bytes, checksum: 1eabaa58f9bf24d34593d59bf89ff6ca (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

In this thesis the entanglement properties of atom-atom, atom-photon, and photon-photon are investigated. The recent developments of quantum computation as well as quantum information and communication have attracted much interest in the generation of these entanglements in the laboratory. To generate atom-photon entanglement, I discuss a model system in the cavity QED setup. By using a four-level atom and two resonant cavity modes, we can generate atom-photon entanglement almost deterministically. An extension of the above model to a six-level atom and again two resonant cavity modes can generate entangled photon pairs by appropriately adjusting system parameters. I then investigate the atom-atom entanglement in a 1D harmonic trap. I show the dependence of the pair entanglement on the scattering length and temperature, as well as the particle symmetry requirement (bosons or fermions). Among many peculiar properties in a 1D system, we briefly discuss the Fermi-Bose duality". While the entanglement properties of a single-channel model have recently been obtained for 1D and 3D systems, I thus study the entanglement of a multi-channel process in a cylindrical harmonic trap. I discuss the dependence of entanglement on the trap geometry. Finally I present detailed studies of the spin mixing between two Rb87 atoms in a single lattice site. The topic is emphasized on various motional state approximations and dipolar effect. Various motional state approximations can cause up to 20% error to experimental data. I also find that the dipolar interaction can lead to an experimentally observable frequency shift in a cylindrical harmonic trap with very large aspect ratio. The spin mixing of spin-2 manifold has also been discussed.

The treaty verification field is of renewed importance as continued nuclear weapons disarmament is prioritized nationally in partnership with other nuclear weapons states. This interest has led to research and development on technologies that could support future U.S. verification missions. A technology employing pulses of high-energy photons from an electron linear accelerator is one technique under consideration. High-energy photons are advantageous as an interrogation source because they penetrate thick shielding and can generate neutrons inside a measurement object. The neutrons would then multiply when presented with an object containing fissile material and allow for detection in a time domain immediately after the pulse. The purpose of this work was to develop an understanding of neutron behavior following a high-energy photon pulse and then develop a tool set to analyze data from this region to determine if a measurement object contains multiplying material, the mass of that material if present, and the moderation in the measurement object. Results indicate the tool sets developed were able to determine multiplication was present accurately in 3 out of 4 realistic verification objects. Additionally the state of the moderation in each object was able to be determined, and the mass could potentially be determined by calibrating to representative samples.

Made available in DSpace on 2014-10-09T12:37:14Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:04Z (GMT). No. of bitstreams: 1 04783.pdf: 1232325 bytes, checksum: c8fd8eb06b52eca9b9846e965159285b (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP