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The Stopping Power of Amorphous and Channelled Silicon at All Energies as Computed with the Binary Encounter Approximation

Description: This thesis utilizes the binary encounter approximation to calculate the stopping power of protons penetrating silicon. The main goal of the research was to make predictions of the stopping power of silicon for low-energy and medium-energy channelled protons, in the hope that this will motivate experiments to test the theory developed below. In attaining this goal, different stopping power theories were compared and the binary encounter approach was applied to random (non-channelled) and high-e… more
Date: December 1994
Creator: Bickel, David, 1970-
Partner: UNT Libraries

Microwave Cavity Test for Superconductivity

Description: The first part of this paper describes the Meissner effect in superconductors which serves as the most definitive evidence for superconductivity. It is shown that the microwave perturbation technique may be used to demonstrate this effect. By measuring the changes of resonant frequency and inverse quality factor Q of a microwave cavity with a small volume of sample loading, the Meissner effect can be shown by using the Slater perturbation equation. The experimental system is described with deta… more
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Date: December 2001
Creator: Tang, Shan
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Theoretical Study of Second Harmonic Generation of a Blue Laser at 486 nm Using a BBO Crystal in a Standing Wave Buildup Cavity

Description: For a spectroscopy purpose, we are interested in producing continuous wave (CW) UV laser light at 243 nm with at least 2 mW power. The theory of nonlinear optics suggests that we should be able to produce a desired 2.9 mW of 243 nm light by second harmonic generation (SHG) from a 50 mW blue laser at 486 nm using a BBO crystal in a build up cavity. The most important physical parameters are calculated. A 10 mm Brewster cut BBO crystal can provide phase matching conditions for coupling two … more
Date: May 2002
Creator: Khademian, Ali
Partner: UNT Libraries
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Photoelectric Emission Measurements for CVD Grown Polycrystalline Diamond Films

Description: We examined CVD grown polycrystalline diamond films having different methane concentrations to detect defects and study the possible correlation between the methane concentration used during the growth process and the defect density. SEM and Raman results show that the amorphous and sp2 carbon content of the films increases with methane concentration. Furthermore, photoelectric emission from diamond is confirmed to be a two-photon process, hence the electrons are emitted from normally unoccupie… more
Date: August 1999
Creator: Hassan, Tarek
Partner: UNT Libraries

Growing carbon nanotubes by chemical vapor deposition technique.

Description: Carbon nanotubes were synthesized in the laboratory using chemical vapor deposition at different methane concentration. I found that a methane concentration of 4 sccm was ideal for well recognizable carbon nanotubes. A higher concentration led to fewer nanotube growth and silicon carbide structure. Coating the sample first with Fe(NO3)3 created a catalyst base on the substrate for the nanotube to adhere and grow on.
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Date: May 2000
Creator: Rajan, Harihar V.
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A Technique for Increasing the Optical Strength of Single-Crystal NaCl and KCl Through Temperature Cycling

Description: This thesis relates a technique for increasing the optical strength of NaCl and KCl single-crystal samples. The 1.06-μm pulsed laser damage thresholds were increased by factors as large as 4.6 for a bulk NaCl single-crystal sample. The bulk laser damage breakdown threshold (LDBT) of the crystal was measured prior to and after heat treatment at 800*C using a Nd:YAG laser operating at 1.06 μm. Bulk and surface LDBTs were also studied on samples annealed at 400° C. These samples showed differences… more
Date: May 1983
Creator: Franck, Jerome B. (Jerome Bruce)
Partner: UNT Libraries
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Dynamic Screening via Intense Laser Radiation and Its Effects on Bulk and Surface Plasma Dispersion Relations

Description: Recent experimentation with excitation of surface plasmons on a gold film in the Kretschmann configuration have shown what appears to be a superconductive effect. Researchers claimed to see the existence of electron pairing during scattering as well as magnetic field repulsion while twisting the polarization of the laser. In an attempt to explain this, they pointed to a combination of electron-electron scattering in external fields as well as dynamic screening via intense laser radiation. Th… more
Date: August 2017
Creator: Lanier, Steven t
Partner: UNT Libraries

Approach to Quantum Information starting from Bell's Inequality (Part I) and Statistical Analysis of Time Series Corresponding to Complex Processes (Part II)

Description: I: Quantum information obeys laws that subtly extend those governing classical information, making possible novel effect such as cryptography and quantum computation. Quantum computations are extremely sensitive to disruption by interaction of the computer with its environment, but this problem can be overcome by recently developed quantum versions of classical error-correcting codes and fault-tolerant circuits. Based on these ideas, the purpose of this paper is to provide an approach to quantu… more
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Date: May 2002
Creator: Failla, Roberto
Partner: UNT Libraries
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Application of the Finite Element Method to Some Simple Systems in One and Two Dimensions.

Description: The finite element method (FEM) is reviewed and applied to the one-dimensional eigensystems of the isotropic harmonic oscillator, finite well, infinite well and radial hydrogen atom, and the two-dimensional eigensystems of the isotropic harmonic oscillator and the propagational modes of sound in a rectangular cavity. Computer codes that I developed were introduced and utilized to find accurate results for the FEM eigensolutions. One of the computer codes was modified and applied to the one-dime… more
Date: May 2002
Creator: Hunnell, Jason C.
Partner: UNT Libraries
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Automatic Frequency Control of Microwave Radiation Sources

Description: Resonant cavity controlled klystron frequency stabilization circuits and quartz-crystal oscillator frequency stabilization circuits were investigated for reflex klystrons operating at frequencies in the X-band range. The crystal oscillator circuit employed achieved better than 2 parts in 10 in frequency stability. A test of the functional properties of the frequency standard was made using the Stark effect in molecules.
Date: August 1979
Creator: Payne, Bobby D.
Partner: UNT Libraries

Brownian Movement and Quantum Computers

Description: This problem in lieu of thesis is a discussion of two topics: Brownian movement and quantum computers. Brownian movement is a physical phenomenon in which the particle velocity is constantly undergoing random fluctuations. Chapters 2, 3 and 4, describe Brownian motion from three different perspectives. The next four chapters are devoted to the subject of quantum computers, which are the signal of a new era of technology and science combined together. In the first chapter I present to a reader … more
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Date: December 2004
Creator: Habel, Agnieszka
Partner: UNT Libraries
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Maxwell's Equations from Electrostatics and Einstein's Gravitational Field Equation from Newton's Universal Law of Gravitation Using Tensors

Description: Maxwell's equations are obtained from Coulomb's Law using special relativity. For the derivation, tensor analysis is used, charge is assumed to be a conserved scalar, the Lorentz force is assumed to be a pure force, and the principle of superposition is assumed to hold. Einstein's gravitational field equation is obtained from Newton's universal law of gravitation. In order to proceed, the principle of least action for gravity is shown to be equivalent to the maximization of proper time along a … more
Date: May 2004
Creator: Burns, Michael E.
Partner: UNT Libraries
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Surface Segregation in Multi-component Systems: Modeling Binary Ni-Al Alloys Using the BFS Method

Description: Although the study of surface segregation has a great technological importance, the work done in the field was for a long time largely restricted to experimental studies and the theoretical work was neglected. However, recent improvements in both first principles and semi-empirical methods are opening a new era for surface scientists. A method developed by Bozzolo, Ferrante, and Smith (BFS) is particularly suitable for complex systems and several aspects of the computational modeling of surface… more
Date: August 2004
Creator: Kasmi, Azeddine
Partner: UNT Libraries
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The Classical Limit of Quantum Mechanics

Description: The Feynman path integral formulation of quantum mechanics is a path integral representation for a propagator or probability amplitude in going between two points in space-time. The wave function is expressed in terms of an integral equation from which the Schrodinger equation can be derived. On taking the limit h — 0, the method of stationary phase can be applied and Newton's second law of motion is obtained. Also, the condition the phase vanishes leads to the Hamilton - Jacobi equation. The s… more
Date: December 1977
Creator: Hefley, Velton Wade
Partner: UNT Libraries
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Test of Gauge Invariance: Charged Harmonic Oscillator in an Electromagnetic Field

Description: The gauge-invariant formulation of quantum mechanics is compared to the conventional approach for the case of a one-dimensional charged harmonic oscillator in an electromagnetic field in the electric dipole approximation. The probability of finding the oscillator in the ground state or excited states as a function of time is calculated, and the two approaches give different results. On the basis of gauge invariance, the gauge-invariant formulation of quantum mechanics gives the correct probabil… more
Date: August 1980
Creator: Wen, Chang-tai
Partner: UNT Libraries

Precision Atomic Spectroscopy with an Integrated Electro- Optic Modulator and DBR Diode Laser at 1083nm

Description: We have explored the use of recently developed high speed integrated electro optic modulators and DBR diode lasers as a tool for precision laser studies of atoms. In particular, we have developed a technique using a high speed modulator as a key element and applied it to the study of the fine structure of the 23P state of atomic helium. This state has been of long standing interest in atomic physics and its study has been the aim of several recent experiments using various precision techniques.… more
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Date: December 1999
Creator: Castillega, Jaime
Partner: UNT Libraries
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A Continuously Sensitive Cloud Chamber

Description: A continuous cloud chamber would be a valuable asset to laboratory work in nuclear and atomic physics. For this reason the construction and investigation of a continuously sensitive diffusion cloud chamber has been undertaken. It is the purpose of this paper to report the design and operating characteristics of such a chamber.
Date: 1951
Creator: Hughes, James E.
Partner: UNT Libraries
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Crystalline Polymorphism of Nitrates

Description: The purpose of this study was to investigate the polymorphism of a group of related compounds. Special emphasis was placed upon the temperature at which transitions occurred and a possible correlation of these temperatures with other properties of the compounds.
Date: 1951
Creator: Shepherd, Jimmie G.
Partner: UNT Libraries
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A Deuterium-Deuterium Type Neutron Source

Description: In view of the advantages of its type, the decision to construct a neutron source of the particle accelerator type was made. The purpose of this thesis is to survey the problems encountered in the construction of the source.
Date: 1951
Creator: Windham, Pat M.
Partner: UNT Libraries
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A Two-Dimensional Model Study of Elastic Waves

Description: In seismic field operations complex problems often arise which cannot be solved mathematically. In recent years investigators in both the commercial and academic fields have begun to approach the problems of elastic wave propagation by the use of seismic scale models. This thesis discusses the results measured from simulated seismic activity on a scale model built by the researcher.
Date: 1955
Creator: Fulton, Thomas K.
Partner: UNT Libraries
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Dipole Moments of Olefenic Diesters

Description: It is the purpose of this paper to present experimental data for the determination of the dielectric constant and the dipole moments for a series of olefenic diesters of the cis and trans configurations.
Date: 1951
Creator: Shipley, Floyd D.
Partner: UNT Libraries
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Absolute Beta Counting Using Thick Sources

Description: The problem with which we shall concern ourselves in this paper is the self-scattering and self-absorption of beta particles by the source.
Date: 1950
Creator: Anderson, Miles E., 1926-
Partner: UNT Libraries
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A Positive Ion Source

Description: This paper describes the construction of a positive ion source of the electrodeless discharge type and may be divided into two main topis; (1) the radio frequency oscillator and power amplifier and associated power supply and (2) the ionization chamber.
Date: 1948
Creator: Hannah, Kenneth W.
Partner: UNT Libraries
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The Stereochemistry of Diphenylhexatriene

Description: The problem with which this paper is concerned has as its basis one of the most important properties of the conjugated system of double bonds found in some organic molecules, namely, the ability to exhibit stereoisomerism.
Date: 1948
Creator: Secrest, Everett Leigh
Partner: UNT Libraries
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