Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisors: Gerald W. Hoffmann and C. Fred Moore. Vita. "Center of mass energy" written as symbols in title. Includes bibliographical references. Also available from UMI.

Orientador: Donato Giorgio Torrieri / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-30T22:50:16Z (GMT). No. of bitstreams: 1 Gambini_GuillermoGeraldoRivera_M.pdf: 5712404 bytes, checksum: 0da05d8acbfc173eed212a7f6e4f6e27 (MD5) Previous issue date: 2016 / Resumo: A equação de Gribov, Levin e Ryskin (GLR) é uma equação de evolução para as funções de distribuição dos gluons que respeita o limite de Froissart. Motivado pelo fato do fluxo elíptico v2 apresentar scaling no momento transversal, na rapidez, no tamanho do sistema, etc. e pela similaridade que esses scalings possuem com o scaling de Bjorken, modificamos a equação GLR adicionando uma dependência angular a ela. Dessa maneira, temos uma equação diferencial parcial não linear do tipo 2+1 que pode apresentar instabilidades nas soluções, gerando v2. A forma geral das soluções foi inspirada pela descomposição de Fourier para a distribuição de momentos das partículas produzidas em colisões entre íons pesados. Duas soluções para os modos instáveis são obtidas e seus significados físicos discutidos / Abstract: The Gribov-Levin-Ryskin (GLR) equation is an evolution equation for gluon distribution functions which respects Froissart's bound. Motivated by the non-obviousness of elliptic flow v2 scaling in transverse momentum, rapidity, system size, etc. being explained by Hydrodynamics, and the similarity they have with Bjorken scaling, the GLR equation is modified by adding an angular dependence to it; therefore, turning it into a 2+1 nonlinear partial differential equation, which can present instabilities in its solutions, generating v2. The general form of the solutions was inspired by the Fourier decomposition for the momentum distribution of produced particles in heavy-ion collisions. Two solutions for the unstable modes are found and their physical meaning is discussed / Mestrado / Física / Mestre em Física / 1370446/2014 / 151922/2014-4 / CAPES / CNPQ

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The effect of ion irradiation and annealing on the microstructure and migration behaviour of implanted Sr and Ag in SiC have been investigated. SiC is used as the main barrier for fission products in modern high temperature gas cooled reactors. An understanding of the transport behaviour of the implanted ions under irradiation by swift heavy ions (SHI) will shed some light into SiC’s effectiveness in the retention of fission products. The diffusion behaviour of silver (Ag) and strontium (Sr) implanted separately into SiC was investigated after irradiation by xenon ions and isochronal annealing methods from 1100 ˚C up to temperatures of 1500 ˚C in step of 100 ˚C for 5 hours. Ion implantation and ion irradiation were performed at room temperature. The implantation fluences in all cases were in the order of 2×10 16 ions per cm 2 . Some of the implanted samples were then irradiated by SHI at different fluences (i.e. 3.4×10 14 and 8.4×10 14 ions per cm 2 ). The implantation depth profiles before and after irradiation and annealing were determined by Rutherford backscattering spectroscopy (RBS). The microstructure of SiC individually implanted with Ag and Sr were investigated using Raman spectroscopy and scanning electron microscopy (SEM). Implantation of Ag and Sr amorphized the SiC, while SHIs irradiation of the as-implanted SiC resulted in limited recrystallization of the initially amorphized SiC. Annealing at 1100 °C caused more recrystallization on the un-irradiated but implanted samples compared to SHI irradiated samples. This poor recrystallization of the irradiated SiC samples was due to the amount of impurities (i.e. concentration of Ag or Sr atoms) retained after annealing at 1100 o C. Raman and SEM results showed that annealing of the un-irradiated but implanted samples at 1100 °C resulted in large average crystal size compared to the irradiated samples annealed in the same conditions. RBS results showed that SHI irradiation alone induced no change in the implanted Ag and Sr. However, annealing the SHI irradiated samples iscohonally up to 1500 ˚C showed a strong diffusion and release of Ag and Sr as compared to the un-irradiated but implanted samples. The differences in the migration behavior of Ag and Sr is due to the difference in SiC structure and recrystallization in the irradiated and un-irradiated but implanted samples. / Thesis (PhD (Physics))--University of Pretoria, 2019. / National Research Foundation (NRF) and The World Academy of Sciences (TWAS). / Physics / PhD (Physics) / Unrestricted

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<p> This report presents a study of the sputtering of vacuum deposited thin films of cadmium sulphide on a (111) face of single crystal silicon by Rutherford backscattering (RBS) technique. Cadmium was found to be preferentially sputtered when bombarded to high fluences of 80 kV Bi+ while no significant preferential sputtering was observed in the case of 40 kV Ar+ bombardment. </p> <p> The structural study by reflection high energy electron diffraction (RHEED) revealed that the films grew epitaxially in the wurtzite structure. The epitaxial relations are (00.1) Cds || (111) Si with [10.0] II [110] Si. </p> <p> Scanning electron microscope (SID4) microphotographs showed smooth surface features with a large grain size (surface grain size was ~ 83 nm) for a film of about 60 nm thickness. </p> <p> The basic structure did not change with highest fluences of Bi+ (Sxlo16 ions/cm2 ) and Ar+ (6.7xlo16 ions/cm2). He+ beam channeling was done for unbombarded and bombarded CdS films. It was found that the critical angle of channeling for cadmium increased for bombarded samples while for sulfur the statistics were too poor for any conclusion. </p> <p> Saturation fluences for bismuth and argon retention were observed and are compared with calculated values. </p> / Thesis / Master of Engineering (MEngr)

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