UNT Theses and Dissertations - 353 Matching Results
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- A Precision Angular Correlation Table and Calculation of Geometrical Correction Factors
- In recent years y-y angular correlations have been very useful in confirming the spins of excited nuclear states. Angular correlation techniques have also been employed to study the electric and magnetic character of excited nuclear states. With these things in mind, it was decided to design, construct, and test a precision angular correlation table.
- Cross Section for the 165/Ho (n, 2n) 164/Ho Reaction at 15.6 MeV
- It was the purpose of this investigation to bring together the ideas and procedures involved in the measurement of (n, 2n) reaction cross sections. Some of the inherent properties of the material under investigation (Holium) are involved in determining these relationships.
- Electron Spin Resonance Absorption in Benzophenone Phenylhydrazone Negative Ion
- This thesis reports an electron spin resonance absorption study of the hyperfine interaction between nuclei and a single "nearly-free" electron in dilute solutions of the benzophenone phenylhydrazone free radical in tetrahydrofuran.
- Temperature Dependence of Line Widths of the Inversion Spectra of Ammonia
- One of the purposes of this work is to investigate modifications that have to be made to a standard source-modulation microwave spectrograph so that it can be used to study gases at various temperatures. Another objective in this work is to determine experimentally the function of temperature that describes how the line widths of microwave spectral lines vary with changing temperature. The most important segment of the study is the temperature dependence of the line width since from an accurate knowledge of this temperature dependence one is able to determine what molecular force fields are present and the relative importance of parts of the molecular force field.
- Size Dependence in the Electrical Conductivity of Bismuth
- In the present investigation, measurements were made at liquid-helium temperatures on single-crystal bismuth samples which had a stair-step geometry in order to study several thicknesses during one helium run. These samples were also thinned to extend the thickness range of the steps to a thinner region. In addition J.E. Parrott's theory is extended to include a diagonal anisotropic relaxation-time tensor and the effect of holes on the size effect. A discussion of the theory of Parrott, and the extension of Parrott's theory in connection with the experimental results is presented.
- Magnetomorphic Oscillations in Cadmium Cylinders
- The work presented here is an experimental investigation of the effect of cylindrical geometry on electrical conductivity, in which single-crystal samples of cadmium at the temperature of liquid helium are used, with the diameter on the order of the electron mean free path.
- Operation and Control of a Radiofrequency Ion Source
- This thesis examines the operation and control of a radiofrequency ion source.
- Analyzing Magnet System for the Electrostatic Accelerator
- 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.
- Thermomagnetic Effects in Antimony at 4.2 [degrees]K
- The purpose of this investigation was to study the thermoelectric effects in a single crystal of antimony at liquid-helium temperatures.
- Vertex Functions in K-Meson-Nucleon Scattering
- The purpose of this study was to investigate some theoretical approaches to the scattering of positive k-mesons by nucleons in an attempt to explain the experimental data. In this work the problem has been investigated by the technique of the weak coupling approximation.
- A Computer Analysis of Complex Gamma-Ray Spectra
- The purpose of this investigation was to provide a method for determining the relative intensities of all gamma rays in a particular spectrum, and thereby determine the relative transition probabilities.
- A Calculation of the Kaon-Neutron Scattering Cross Section
- 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.
- Galvanomagnetic Phenomena in Arsenic at Liquid Helium Temperatures
- The purpose of this investigation was to study some of the transport effects in a single crystal of arsenic at liquid helium temperatures in a magnetic field up to twenty-four kilogauss. The experimental coefficients determined were the isothermal magnetoresistivity and the isothermal Hall resistivity.
- Dynamical Friction Coefficients for Plasmas Exhibiting Non-Spherical Electron Velocity Distributions
- This investigation is designed to find the net rate of decrease in the component of velocity parallel to the original direction of motion of a proton moving through an electron gas exhibiting a non-spherical velocity distribution.
- Electron Transport in Bismuth at Liquid Helium Tempratures
- To obtain information on the band structure of bismuth, galvanomagnetic potentials were measured in a single crystal at liquid-helium and liquid-nitrogen temperatures. These measurements were analyzed for information on the different carriers, particularly for the existence of a high-mobility band of holes.
- A Correction Factor for the First Born Approximation
- This thesis looks at a Schroedinger equation and the Born approximation.
- Stochastic Mechanical Systems
- To understand the phenomena associated with such stochastic processes and to predict, at least qualitatively, the behavior of mechanical systems within environments which are completely random in time, new mechanical tools are necessary. Fortunately, the derivation of these tools does not necessitate a complete departure from existing theories. In fact, they may be considered as an extension of the well-defined theory of the integral transform, in particular, the exponential Fourier integral transform.
- D-D and D-T Neutron Excitation of Energy Levels in Cs133
- The purpose of this experiment was to make positive assignment of the Cs133 energy levels excited by the inelastic scattering of neutrons.
- Energy Losses of Protons Projected through a Plasma Due to Collisions with Electrons of the Plasma for a Variety of Non-Maxwellian Electron Velocity Distributions
- The purpose of this thesis is to study energy losses suffered by protons in traversing a plasma through collision with the electrons of the plasma. For these electrons a variety of non-Maxwellian velocity distributions are assumed.
- A Study of Emitter Drift in Transistors
- The purpose of this investigation was to determine the parameters of emitter drift and to suggest a mechanism for this phenomenon.
- Shubnikov-de Haas Effect in Arsenic
- This thesis studies the Shubnikov-de Haas effect in arsenic.
- Gurevich Magnetomorphic Oscillations in Single Crystals of Aluminum at Helium Temperatures
- The Sondheimer theory was tested by looking for oscillatory phenomena in a group of single crystals representing a range in dimensions from matchbox geometry to thin-film geometry. The single crystals were identical with respect to impurity content, strain, orientation, surface condition, and probe placement.
- Size Effect in the Electrical Conductivity of Bismuth
- If a physical dimension of a metallic specimen is comparable with, or smaller than, the mean free path of the conduction electrons, then the observed electrical conductivity will be less than that of a conventional bulk sample. This phenomenon is called a size effect, and is the result of electron scattering from the specimen surfaces. In the present investigation, measurements were made on electropolished monocrystalline specimens ranging from matchbox geometry to thick-film geometry in order to obtain further information on the size effect in bismuth at liquid helium temperatures.
- Effect of Sample Geometry on Magnetomorphic Oscillations in the Hall Effect in Cadium at Liquid-Helium Temperatures
- This thesis presents observations on size-effect oscillations in the Hall effect in an oriented single crystal of highly pure cadmium at liquid-helium temperatures. All measurements were made in transverse magnetic field.
- Boundary Scattering of Electrons in Thin Cadmium Single Crystals
- In the present investigation, zinc was plated onto a cadmium crystal to determine the effect on the scattering parameter.
- Cross Section Measurements in Praseodymium-141 as a Function of Neutron Bombarding Energy
- Using the parallel disk method of activation analysis, the (n,2n) reaction cross section in 141-Pr was measured as a function of neutron energy in the range 15.4 to 18.4 MeV. The bombarding neutrons were produced from the 3-T(d,n)4-He reaction, where the deuterons were accelerated by the 3-MV Van de Graff generator of the North Texas Regional Physics Laboratory in Denton, Texas.
- Phase Shift Determination for Elastic Potential Scattering, Using the IBM 360-50 Computer
- The primary objective of this paper is to present a computerized method for the extraction of phase shifts from an angular distribution. This was accomplished using a least squares curve fitting routine.
- Nuclear Reactions on the Palladium Isotopes
- The problem of interest in this investigation was to determine the cross sections of five nuclear reactions which occur when irradiating natural palladium with neutrons which have energy values of 15.1, 15.9, and 16.3 MeV. The cross sections were measured relative to a copper monitor which was "sandwitched" in with the palladium target.
- A Study of the Decay Levels of 169/Tm69
- The purpose of this investigation was to study the radiations of the 169/Tm nucleus as it de-excites after the electron capture decay of the 169/Yb. Numerous unreported gammas were present in the sample. The origins of these gamma rays were found.
- Carbon Contamination Measurements in Single Silicon Crystals
- 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.
- The Effects of Lead Placement and Sample Shape in the Measurement of Electrical Resistivity
- This thesis is a study of the effects of lead placement and sample shape in the measurement of electrical resistivity.
- A Method for Calculating Foil Depression Factors
- As disc-shaped detectors are one of the primary means of measuring the neutron density, a better solution is desirable if the error due to the depression factor is to be made negligible. In this paper, an attempt is made to solve this problem in the oblate spheroidal co-ordinate system which most nearly describes the disc-shaped detector, so that solutions may be obtained that describe depression factors for detectors of varying thicknesses and radii.
- A Determination of the Bothe Depression Factor for Discs in Water
- The purpose of this work is to determine experimentally the depression of the neutron density by a detecting foil. The depression factor is known as the "self-shading" of the foil.
- Variational Wave Function for Sodium
- The practical method of applying the variation principle to the calculation of the energy of an atom demands a trial function which contains variable parameters. The previous work done using this approach was based on the use of some combination of hydrogenic wave functions containing parameters inserted in appropriate places. The present calculation of the energy of the eleven-electron atom has been brought about using this method.
- Neutron Density Depression Due to an Oblate Spheroidal Detector
- In this paper, two projects have been undertaken. First, Workman's calculations have been checked to a higher degree of approximation to determine the accuracy of his method. Second, a new set of boundary conditions has been developed for obtaining solutions of the neutron diffusion equation which do not depend on the solution of the equation inside the detector.
- Foil Depression Factors for Disc-shaped Detectors
- The generalized data which are presented in this thesis are the culmination of the determination of the foil depression factor using oblate spheroidal coordinates.
- Thermomagnetic Phenomena in Antimony at Liquid Helium Temperatures
- The purpose of this investigation was to study head-transport phenomena in a single crystal of antimony at liquid helium temperatures. In particular, the longitudinal and transverse components of the thermal resistivity tensor were measured as a function of magnetic field up to eighteen kilogauss.
- Thermal Properties of a Single Crystal of Bismuth at Liquid-helium Temperatures
- The purpose of this investigation was the determination of the thermal conduction properties of a single crystal of bismuth at liquid-helium temperatures in magnetic fields up to eighteen kilogauss.
- Extinguishment of a Low-pressure Argon Discharge by a Magnetic Field
- The experiment in this study involves the extinguishment of a low-pressure argon discharge by a magnetic field.
- A Vacuum Tube for an Electrostatic Accelerator
- The purpose of this study has been to design a prototype accelerating tube, to determine the correct point shape and spacing needed to produce corona current along the tube for the case of negative-point-to-positive-plane discharge, and to study the voltage-gradient characteristics of short sections of the tube when they were evacuated to a low internal pressure.
- Magnetically Driven Instabilities in Gas Discharges
- In the present experiment a gas discharge plasma generator was designed and constructed and a search was made for evidence of a plasma instability due to the influence of an externally applied magnetic field. The evidence for such an unstable mode of operation is too indirect to make a possible conclusion, but an approach to more certain identification will be indicated.
- The Use of Mossbauer Effect for the Study of Recoilless Rayleigh Scattering of Low-Energy Gamma Rays from Sodium Chloride
- Evidence that recoilless emission and absorption exist may be shown by an experiment in which the source gamma rays are allowed to pass through a suitable absorber to a detector.
- Magnetic Susceptibility of a Crystalline Free Radical
- The entirety of the investigation discussed in this paper was confined to a study of the spin resonance properties of unpaired electrons of an organic free radical. In the remainder of the paper the theory of electron spin resonance, the apparatus used in the investigation, and the experimental results obtained are discussed in that order.
- Proton Nuclear Magnetic Resonance in Mica
- The experiments to be described here were undertaken for the purpose of determining, if possible, by NMR techniques whether or not the hydroxyl protons in mica are bound in a regular crystalline array, and, if so, whether or not the hydroxyl protons occur in reasonably isolated pairs as in waters of hydration.
- Some Galvanomagnetic and Thermomagnetic Effects in a Single Crystal of Antimony
- The purpose of this investigation is to develop techniques of experimentation in the field of electron transport phenomena.
- Backscattering from Prolate Spheroids at Microwave Frequencies
- This thesis examines backscattering from prolate spheroids at microwave frequencies.
- Design and Construction of a Positive Radio-Frequency Ion Source for the Production of Negative Ions
- It is the purpose of this paper to present a detailed account of the design and construction of this positive-ion source and associated equipment.
- Design and Testing of a Coincidence System
- This paper is concerned with the design, testing and performance of a coincidence system, the proposed North Texas State College accelerator.
- Quaternion Representation of Crystal Space Groups
- This investigation is designed to find quaternion operators which will generate selected space groups and which are more convenient to manipulate in some important types of problems.
- Nuclear Magnetic Resonance in Hydrated Crystals - Potassium Oxalate Monohydrate
- The problem of this study was the measurement of the proton-proton separation in the water molecule of hydration in a single crystal of potassium oxalate monohydrate.