Graduation date: 1997

Graduation date: 1995

Thesis (Ph. D.)--Oregon Graduate Center, 1980.

No description available.

In recent and upcoming years new lasers are being constructed withever higher intensity. These lasers open up the possibility of probingthe high intensity regime of particle physics, which will lead to etherconrming our current models in this regime or the discovery of beyondstandard model physics. However most previous theoretical results in thisarea are based old assumptions about the intensity and shape of the laserpulse that are no longer valid. In this thesis we calculate the tree-levelprobabilities for multi photon emission from an electron propagating inan arbitrary plane wave electromagnetic eld. We show that the classicallimit of our result agrees with the purely classical description of the sameevent. We calculate the soft emission correction to non-linear Comptonscattering. We conclude that our results are infrared divergent and arguethat this will be solved by including loop contributions to the process. Ourresults provide an important component for the theoretical predictions forthe outcome of scattering experiments in high intensity background eld.This thesis will add to the understanding of high intensity QED.

There are two principal techniques for performing Monte Carlo electron transport computations. The first, and least common, is the full track-structure method. This method individually models all physical electron interactions including elastic scatter, electron impact ionization, radiative losses and excitations. However, because of the near infinite size of electron interaction cross-sections and highly anisotropic scattering behavior, this method requires an enormous amount of computation time. Alternatively, the Condensed History (CH) method for electron transport lumps the average effects of multiple energy loss and scattering events into one single pseudo-event, or step. Because of this approximation, the CH method can be orders of magnitude faster than the trackstructure method. While the CH method is reasonably accurate in many situations, it can be inaccurate for simulations involving microscopic site sizes such as those often found in radiation biology. For radiation biology and other microdosimetry applications, a computational device called a Field Programmable Gate Array (FPGA) is capable of executing track-structure Monte Carlo electron transport simulations as fast as, or faster than a standard computer performing transport via the CH method—and, it does so with the additional accuracy and level of detail provided by the track-structure method. In this dissertation, data from FPGA based track-structure electron transport computations are presented for five test cases, ranging in complexity from simple slab-style geometries to radiation biology applications involving electrons incident on endosteal bone surface cells. Even for the most complex test case presented, an FPGA is capable of evaluating track-structure electron transport problems more than 500 times faster than a standard computer can perform the same track-structure simulation, and with comparable accuracy.

Abstract In this study, ZrN films were deposited on silicon wafer¡Bcopper and aluminum sheets by reactive sputtering of Zr target at room temperature in a mixed N2-Ar atmosphere with N2 gas flow rates of 5 and 6 sccm. Films of ZrN about 1£gm thick were annealed at various temperatures in order to study the grain growth and the inter-diffusion of atoms. Electron probe X-ray microanalyzer¡]EPMA¡^ showed that the as-deposited ZrN films were stoichiometric. The ring patterns of electron diffraction in transmission electron microscope (TEM) indicated that only ZrN was present without any Zr metal. The grain size of ZrN showed no apparent change after annealing at 900¢J and 1000¢J, but showed that¡]200¡^ orientation is preferred to ¡]111¡^orientation. No Zr-Si compound were found at the ZrN/Si interface after annealing. It was revealed that the ZrN grain size in the ZrN/Si interface was about 5¡ã15 nm, then broadened to columnar structure of 20¡ã50nm in diameter away from the interface. The grain size of ZrN on Cu substrate was 3¡ã15 nm at the ZrN/Cu interface and leave away from the interface was 10¡ã80 nm. No Cu-Zr compound was found at the interface after annealing at 650¢J for 1 hour.

Hole-doped colossal magnetoresistance (CMR) materials La1-xAxMnO3 (A=alkaline metal, 0≤x≤1) has been extensively studied because of its colossal magnetoresistance (CMR) characteristic in a magnetic field. Recently, many suspicious electron-doped CMR materials have been reported. However, none of these ¡§pure phases¡¨ were supported directly by experiment evidences, instead, various impurity phases were found. The La0.7Ce0.3MnO3 (LCeMO) target forming by a solid state reaction method, after analyzing its crystal structure and electric transport properties, is also found to be decomposed into CeO2 impurity and a La deficient La1-dMnO3 phases. This is believed to because the doped Ce4+ ions transforming the Mn3+ ions to Mn2+ whose larger ionic radius (aMn2+ =0.83Å), comparing to that of Mn3+(0.645Å), makes the MnO6 structure instable. Therefore, instead of forming an instable phase, the sample prefers to decompose into different phases. In this study, we propose to grow LCeMO films on an in-plane-enlarged STO bottom layer which was grown under a tensile strain on MgO (c=4.216Å) substrate. We found that all as grown films exhibits insulating behavior. Nevertheless, the samples after a rapid thermal annealing process can easily decompose the films into multiphase.

Thesis (M.Sc.)--York University, 2007. Graduate Programme in Physics and Astronomy. / Typescript. Includes bibliographical references (leaves 77-79). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR38785

Thesis (Ph. D.)--Lehigh University, 2001. / Includes vita. Includes bibliographical references (leaves 200-206).