Physics Commons^™

Gamma-Ray Optical Studies Of ⁷³Ge And ⁵⁷Fe, Walter Carlton Mcdermott Iii

Physics Theses & Dissertations

The research described herein is among the first attempts to test one of the more popular theories for development of a gamma-ray laser. This work is a "marriage" between the Borrmann effect, which is a consequence of the dynamical theory of x-ray diffraction, and time-filtering which comes from time-domain Mossbauer spectroscopy.

Our experiments involved the search for a nuclear Borrmann effect and the subsequent time-filtering effect using ⁵⁷Fe and ⁷³Ge. In both cases, no nuclear Borrmann effect was observed; however, the methodology and criteria necessary for such an observation with any isotope were documented. The procedures necessary for …

The Projector Basis Method For Electronic Band Structure Calculations, Christopher Haas

Dissertations, Theses, and Masters Projects

Over the last several decades, two methods have emerged as the standard tools for the calculation of electronic band structures. These methods, the Car-Parinello plane wave method and the linear augmented plane wave method (LAPW), each have strengths and weaknesses in different regimes of physical problems. The Car-Parinello algorithm is ideal for calculations with soft pseudopotentials and large numbers of atoms. The LAPW method, on the other hand, easily handles all-electron and hard-core pseudopotential calculations with a small number of atoms. The projector basis method, presented here, is a hybrid mixed basis method which allows the calculation of moderately large …

Modelling An Optical Fiber Bragg Grating, Claudio Oliveira Egalon

Electrical & Computer Engineering Theses & Dissertations

A theoretical investigation of a single mode optical fiber with one and two superimposed Bragg grating is presented. The formulation relies in the determination of an approximate solution in the asymptotic region of one of the fiber parameters. A correction is then applied to the asymptotic solution using the Method of the Successive Approximations also known as the Piccard Method. The approximation was then compared to the numerical solution using the Runge-Kutta method. Assuming that each Bragg grating has modulation frequencies given by Ω₁ and Ω₂, it has been found that the second Bragg grating shifts the …