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**Department:**Department of Physics

**Resource Type:**Thesis or Dissertation

### Absolute Beta Counting Using Thick Sources

**Date:**1950

**Creator:**Anderson, Miles E., 1926-

**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.

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### Accelerator Mass Spectrometry Studies of Highly Charged Molecular Ions

**Date:**December 1994

**Creator:**Kim, Yong-Dal

**Description:**The existence of singly, doubly, and triply charged diatomic molecular ions was observed by using an Accelerator Mass Spectrometry (AMS) technique. The mean lifetimes of 3 MeV boron diatomic molecular ions were measured. No isotopic effects on the mean lifetimes of boron diatomic molecules were observed for charge state 3+. Also, the mean lifetime of SiF^3+ was measured.

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### Analysis of Biological Materials Using a Nuclear Microprobe

**Date:**December 2014

**Creator:**Mulware, Stephen Juma

**Description:**The use of nuclear microprobe techniques including: Particle induced x-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) for elemental analysis and quantitative elemental imaging of biological samples is especially useful in biological and biomedical research because of its high sensitivity for physiologically important trace elements or toxic heavy metals. The nuclear microprobe of the Ion Beam Modification and Analysis Laboratory (IBMAL) has been used to study the enhancement in metal uptake of two different plants. The roots of corn (Zea mays) have been analyzed to study the enhancement of iron uptake by adding Fe (II) or Fe (III) of different concentrations to the germinating medium of the seeds. The Fe uptake enhancement effect produced by lacing the germinating medium with carbon nanotubes has also been investigated. The aim of this investigation is to ensure not only high crop yield but also Fe-rich food products especially from calcareous soil which covers 30% of world’s agricultural land. The result will help reduce iron deficiency anemia, which has been identified as the leading nutritional disorder especially in developing countries by the World Health Organization. For the second plant, Mexican marigold (Tagetes erecta), the effect of an arbuscular mycorrhizal fungi (Glomus intraradices) for the ...

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### Analyzing Magnet System for the Electrostatic Accelerator

**Date:**August 1954

**Creator:**Young, Thomas E.

**Description:**This thesis describes the design and construction of a linear accelerator, specifically, a positive-ion source, a high voltage supply, an accelerating column, and the necessary associated vacuum system.

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**Permallink:**digital.library.unt.edu/ark:/67531/metadc130409/

### Anderson Localization in Two-Channel Wires with Correlated Disorder: DNA as an Application

**Date:**December 2007

**Creator:**Bagci, V. M. Kemal

**Description:**This research studied the Anderson localization of electrons in two-channel wires with correlated disorder and in DNA molecules. It involved an analytical calculation part where the formula for the inverse localization length for electron states in a two-channel wire is derived. It also involved a computational part where the localization length is calculated for some DNA molecules. Electron localization in two-channel wires with correlated disorder was studied using a single-electron tight-binding model. Calculations were within second-order Born-approximation to second-order in disorder parameters. An analytical expression for localization length as a functional of correlations in potentials was found. Anderson localization in DNA molecules were studied in single-channel wire and two-channel models for electron transport in DNA. In both of the models, some DNA sequences exhibited delocalized electron states in their energy spectrum. Studies with two-channel wire model for DNA yielded important link between electron localization properties and genetic information.

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### Angular Dependence of the Stopping Processes and the Yields of Ion-induced Electron Emission from Channeled MEV Protons in <100> Silicon Foils

**Date:**December 1993

**Creator:**Zhao, Zhiyong

**Description:**The present work reports the experimental evidence of anomalous energy loss, energy straggling, and the corresponding ion-induced electron emission yields of channeled protons in silicon.

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**Permallink:**digital.library.unt.edu/ark:/67531/metadc279025/

### The Angular Distribution and Total Flux of Neutrons Obtained from the Deuterium-Tritium Reaction

**Date:**1956

**Creator:**Duggan, Jerome L.

**Description:**Mono-energetic neutrons have been produced with the low-voltage Cockroft-Walton accelerator at North Texas State College using two different reactions. It is the purpose of this paper to report the angular distribution and total flux of the neutrons obtained from the T(D,n) reaction.

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### The Angular Distribution of the Deuterium-Deuterium Neutrons with 100 Kev Deuterons

**Date:**1956

**Creator:**Hackfield, Bobby J.

**Description:**It is the purpose of this paper to present the experimental techniques used in obtaining. 3.25 MeV neutrons from the H2(d,n)He3 reaction, as well as an analysis of the experimental data.

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### Anisotropic Relaxation Time for Solids with Ellipsoidal Fermi Surfaces

**Date:**May 1971

**Creator:**Fuchser, Troy Denrich

**Description:**Many solids have Fermi surfaces which are approximated as ellipsoids. A comprehensive solution for the magnetoconductivity of an ellipsoid is obtained which proves the existence of a relaxation time tensor which can be anisotropic and which is a function of energy only.

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### Anomalous Behavior in the Rotational Spectra of the v₈=2 and the v₈=3 Vibrations for the ¹³C and ¹⁵N Tagged Isotopes of the CH₃CN Molecule in the Frequency Range 17-95 GHz

**Date:**December 1990

**Creator:**Al-Share, Mohammad A. (Mohammad Abdel)

**Description:**The rotational microwave spectra of the three isotopes (^13CH_3^12C^15N, ^12CH_3^13C^15N, and ^13CH_3^13C^15N) of the methyl cyanide molecule in the v_8=3, v_8=2, v_7=1 and v_4=1 vibrational energy levels for the rotational components 1£J£5 (for a range of frequency 17-95 GHz.) were experimentally and theoretically examined. Rotational components in each vibration were measured to determine the mutual interactions in each vibration between any of the vibrational levels investigated. The method of isotopic substitution was employed for internal tuning of each vibrational level by single and double substitution of ^13C in the two sites of the molecule. It was found that relative frequencies within each vibration with respect to another vibration were shifted in a systematic way. The results given in this work were interpreted on the basis of these energy shifts. Large departure between experimentally measured and theoretically predicted frequency for the quantum sets (J, K=±l, ϑ=±1), Kϑ-l in the v_8=3 vibrational states for the ^13c and ^15N tagged isotopes of CH_3CN showed anomalous behavior which was explained as being due to Fermi resonance. Accidently strong resonances (ASR) were introduced to account for some departures which were not explained by Fermi resonance.

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### Antiferromagnetic Ordering in Picryl-Amino-Carbazyl

**Date:**August 1964

**Creator:**Porter, Wilbur A.

**Description:**The purpose of the experiment was to investigate other paramagnetic salts to determine whether the W. B. perchlorate type peak was more common than previously suspected. An organic salt, picryl-n-amino-carbazyl, was chosen.

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### Application of the Finite Element Method to Some Simple Systems in One and Two Dimensions.

**Date:**May 2002

**Creator:**Hunnell, Jason C.

**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-dimensional unbound quantum mechanical system of a square barrier potential and also provided accurate results.

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### Application of the Wigner Formalism to a Slightly Relativistic Quantum Plasma

**Date:**August 1967

**Creator:**Harper, John H.

**Description:**A slightly relativistic fermion gas is described by the dynamical theory obtained from the Wigner distribution function. The problem is approached in a self-consistent manner including the two-body Darwin Hamiltonian. The goal is to find the departures from equilibrium and dispersion relations for wave propagation in the gas.

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**Permallink:**digital.library.unt.edu/ark:/67531/metadc130850/

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

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**Date:**May 2002

**Creator:**Failla, Roberto

**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 quantum information by analyzing and demonstrating Bell's inequality and by discussing the problems related to decoherence and error-correcting. II: The growing need for a better understanding of complex processes has stimulated the development of new and more advanced data analysis techniques. The purpose of this research was to investigate some of the already existing techniques (Hurst's rescaled range and relative dispersion analysis), to develop a software able to process time series with these techniques, and to get familiar with the theory of diffusion processes.

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**Permallink:**digital.library.unt.edu/ark:/67531/metadc3092/

### Automatic Frequency Control of Microwave Radiation Sources

**Date:**August 1979

**Creator:**Payne, Bobby D.

**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.

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### Backscattering from Prolate Spheroids at Microwave Frequencies

**Date:**1956

**Creator:**Sybert, Jim

**Description:**This thesis examines backscattering from prolate spheroids at microwave frequencies.

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**Permallink:**digital.library.unt.edu/ark:/67531/metadc107919/

### Ballistic Deposition: Global Scaling and Local Time Series.

**Date:**December 2003

**Creator:**Schwettmann, Arne

**Description:**Complexity can emerge from extremely simple rules. A paradigmatic example of this is the model of ballistic deposition (BD), a simple model of sedimentary rock growth. In two separate Problem-in-Lieu-of Thesis studies, BD was investigated numerically in (1+1)-D on a lattice. Both studies are combined in this document. For problem I, the global interface roughening (IR) process was studied in terms of effective scaling exponents for a generalized BD model. The model used incorporates a tunable parameter B to change the cooperation between aggregating particles. Scaling was found to depart increasingly from the predictions of Kardar-Parisi-Zhang theory both with decreasing system sizes and with increasing cooperation. For problem II, the local single column evolution during BD rock growth was studied via statistical analysis of time series. Connections were found between single column time series properties and the global IR process.

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### Boundary Scattering of Electrons in Thin Cadmium Single Crystals

**Date:**August 1968

**Creator:**Fortmayer, Gary William

**Description:**In the present investigation, zinc was plated onto a cadmium crystal to determine the effect on the scattering parameter.

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**Permallink:**digital.library.unt.edu/ark:/67531/metadc130996/

### Brownian Movement and Quantum Computers

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**Date:**December 2004

**Creator:**Habel, Agnieszka

**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 the two topics of my problem in lieu of thesis. In the second chapter I explain the idea of Brownian motion, its interpretation as a stochastic process and I find its distribution function. The next chapter illustrates the probabilistic picture of Brownian motion, where the statistical averages over trajectories are related to the probability distribution function. Chapter 4 shows how to derive the Langevin equation, introduced in chapter 1, using a Hamiltonian picture of a bath with infinite number of harmonic oscillators. The chapter 5 explains how the idea of quantum computers was developed and how step-by-step all the puzzles for the field of quantum computers were created. The next chapter, chapter 6, discus the basic quantum unit of information ...

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### A Calculation of the Kaon-Neutron Scattering Cross Section

**Date:**June 1966

**Creator:**Hooper, Robert Gibson

**Description:**The purpose of this investigation was to study the scattering processes of K+ mesons with neutrons. In order to do such a study one must first make certain basic assumptions about the type of interaction involved and then proceed to calculate physically meaningful qualities which describe the processes. Thus, the problem is this: assuming the validity of Feynman's rules for these strongly interacting particles, calculate the differential and total scattering cross sections for the interaction of scalar K+ mesons and neutrons.

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### Carbon Contamination Measurements in Single Silicon Crystals

**Date:**December 1970

**Creator:**Logsdon, Lawrence E.

**Description:**The intent of this investigation was to directly measure the amount of carbon contamination in a single silicon crystal and, in so doing, develop a mathematical procedure that would be applicable to other contaminants in other substances.

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**Permallink:**digital.library.unt.edu/ark:/67531/metadc131331/

### Carbon K-Shell X-Ray and Auger-Electron Cross Sections and Fluorescence Yields for Selected Molecular Gases by 0.6 To 2 .0 MeV Proton Impact

**Date:**August 1986

**Creator:**Bhalla, Raj P. (Raj Pal), 1948

**Description:**Absolute K-shell x-ray cross sections and Auger-electron cross sections are measured for carbon for 0.6 to 2.0 MeV proton incident on CH₄, n-C₄H₁₀ (n-Butane), i-C₄H₁₀ (isobutane), C₆H₆ (Benzene), C₂H₂ (Acetylene), CO and CO₂. Carbon K-shell fluorescence yields are calculated from the measurements of x-ray and Auger-electron cross sections. X-ray cross sections are measured using a variable geometry end window proportional counter. An alternate method is described for the measurement of the transmission of the proportional counter window. Auger electrons are detected by using a constant transmission energy Π/4 parallel pi ate electrostatic analyzer. Absolute carbon K-shell x-ray cross sections for CH₄ are compared to the known results of Khan et al. (1965). Auger-electron cross sections for proton impact on CH₄ are compared to the known experimental values of RΦdbro et al. (1979), and to the theoretical predictions of the first Born and ECPSSR. The data is in good agreement with both the first Born and ECPSSR, and within our experimental uncertainties with the measurements of RΦdbro et al. The x-ray cross sections, Auger-electron cross sections and fluorescence yields are plotted as a function of the Pauling charge, and show significant variations. These changes in the x-ray cross sections are compared ...

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### Carbon Nanotube/Microwave Interactions and Applications to Hydrogen Fuel Cells.

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**Date:**May 2004

**Creator:**Imholt, Timothy James

**Description:**One of the leading problems that will be carried into the 21st century is that of alternative fuels to get our planet away from the consumption of fossil fuels. There has been a growing interest in the use of nanotechnology to somehow aid in this progression. There are several unanswered questions in how to do this. It is known that carbon nanotubes will store hydrogen but it is unclear how to increase that storage capacity and how to remove this hydrogen fuel once stored. This document offers some answers to these questions. It is possible to implant more hydrogen in a nanotube sample using a technique of ion implantation at energy levels ~50keV and below. This, accompanied with the rapid removal of that stored hydrogen through the application of a microwave field, proves to be one promising avenue to solve these two unanswered questions.

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### Chaos and Momentum Diffusion of the Classical and Quantum Kicked Rotor

**Date:**August 2005

**Creator:**Zheng, Yindong

**Description:**The de Broglie-Bohm (BB) approach to quantum mechanics gives trajectories similar to classical trajectories except that they are also determined by a quantum potential. The quantum potential is a "fictitious potential" in the sense that it is part of the quantum kinetic energy. We use quantum trajectories to treat quantum chaos in a manner similar to classical chaos. For the kicked rotor, which is a bounded system, we use the Benettin et al. method to calculate both classical and quantum Lyapunov exponents as a function of control parameter K and find chaos in both cases. Within the chaotic sea we find in both cases nonchaotic stability regions for K equal to multiples of π. For even multiples of π the stability regions are associated with classical accelerator mode islands and for odd multiples of π they are associated with new oscillator modes. We examine the structure of these regions. Momentum diffusion of the quantum kicked rotor is studied with both BB and standard quantum mechanics (SQM). A general analytical expression is given for the momentum diffusion at quantum resonance of both BB and SQM. We obtain agreement between the two approaches in numerical experiments. For the case of nonresonance the ...

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