UNT Theses and Dissertations - 42 Matching Results

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Proton-Induced L-shell X-Rays of Pr, Sm, Eu, Gd, and Dy

Description: Characteristic L-shell x rays of the five rare earths Pr, Sm, Eu, Gd, and Dy were studied in this work. The x rays were produced by ionization from 0.3 to 2.0 MeV protons from the 2.0 MV Van de Graaff at North Texas State University. Total L-shell ionization and x-ray production cross sections were measured for Sm and compared to the BEA, CBEA and PWBA theories. Total L-shell ionization cross sections were measured for Pr, Eu, Gd, and Dy and compared to the BEA, CBEA, and PWBA. The CBEA and PW… more
Date: August 1974
Creator: Abrath, Frederick G.
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Inversion-Asymmetry Splitting of the Conduction Band in N-Type Indium Antimonide

Description: The origin of the Shubnikov-de Haas effect, the strain theory developed by Bir and Pikus, and a simple, classical beating-effects model are discussed. The equipment and the experimental techniques used in recording the Shubnikov-de Haas oscillations of n-type indium antimonite are described. The analysis of the experimental data showed that the angular anisotropy of the period of SdH oscillations at zero stress was unmeasurable for low concentration samples as discussed by other workers. Thus t… more
Date: December 1976
Creator: Bajaj, Bhushan D.
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Distribution of Nighttime F-region Molecular Ion Concentrations and 6300 Å Nightglow Morphology

Description: The purpose of this study is two-fold. The first is to determine the dependence of the molecular ion profiles on the various ionospheric and atmospheric parameters that affect their distributions. The second is to demonstrate the correlation of specific ionospheric parameters with 6300 Å nightglow intensity during periods of magnetically quiet and disturbed conditions.
Date: December 1970
Creator: Brasher, William Ernest, 1939-
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Steady-state and Dynamic Probe Characteristics in a Low-density Plasma

Description: The problem with which this investigation is concerned is that of determining the steady-state and dynamic characteristics of the admittance of a metallic probe immersed in a laboratory plasma which has the low electron densities and low electron temperatures characteristic of the ionospheric plasma. The problem is separated into three related topics: the design and production of the laboratory plasma, the measurement of the steady-state properties of dc and very low frequency probe admittance,… more
Date: December 1970
Creator: Bunting, William David
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Relaxation Time Measurements for Collision Processes in the Surface Layers of Conductors and Semiconductors Near 10 Ghz

Description: This thesis represents one phase of a joint effort of research on the properties of liquids and solids. This work is concerned primarily with the microwave properties of solids. In this investigation the properties exhibited by conductor and semiconductor materials when they are subjected to electromagnetic radiation of microwave frequency are studied. The method utilized in this experiment is the perturbation of a resonant cavity produced by introduction of a cylindrically shaped sample into i… more
Date: December 1973
Creator: Childress, Larry Wayne
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Quantized Hydrodynamics

Description: The object of this paper is to derive Landau's theory of quantized hydrodynamics from the many-particle Schroedinger equation. Landau's results are obtained, together with an additional term in the Hamiltonian.
Date: August 1972
Creator: Coomer, Grant C.
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K-Shell Ionization Cross Sections For Elements Se To Pd: 0.4 To 2.0 MeV

Description: K-Shell ionization cross section for protons over the energy range of 0.4 to 2.0 MeV have been measured on thin targets of the elements Se, Br, Rb, Sr, Y, Mo and Pd. Total x-ray and ionization cross sections for the K-shell are reported. The experimental values of the ionization cross sections are compared to the non-relativistic plane-wave Born approximation, the binary-encounter approximation, the constrained binary-encounter approximation, and the plane-wave Born approximation with correctio… more
Date: December 1974
Creator: Criswell, Tommy L.
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Electron Density and Collision Frequency Studies Using a Resonant Microwave Cavity as a Probe

Description: Electron densities and collision frequencies were obtained on a number of gases in a dc discharge at low pressures (0.70-2mm of Hg). These measurements were performed by microwave probing of a filament of the dc discharge placed coaxially in a resonant cavity operating in a TM₀₁₀ mode. The equipment and techniques for making the microwave measurements employing the resonant cavity are described. One of the main features of this investigation is the technique of differentiating the resonance sig… more
Date: May 1973
Creator: Freeman, Ronald Harold
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Target Thickness Dependence of Cu K X-Ray Production for Ions Moving in Thin Solid Cu Targets

Description: Measurements of the target thickness dependence of the target x-ray production yield for incident fast heavy ions are reported for thin solid Cu targets as a function of both incident projectile atomic number and energy. The incident ions were F, Al, Si, S, and CI. The charge state of the incident ions was varied in each case to study the target x-ray production for projectiles which had an initial charge state, q, of q = Z₁, q = Z₁ - 1, and q < Z₁ - 1 for F, Al, Si, and S ions and q = Z₁ - 1 a… more
Date: December 1977
Creator: Gardner, Raymond K.
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A Decay Scheme for 164 Ho

Description: The present investigation was prompted by several considerations. In previous studies there was considerable variance with regard to the reported values for the half-lives of the isomeric and ground states in 164 Ho. There was also considerable variance with regard to the values reported for the branching ratios and the relative intensities of the transitions. Thus a further study of the problem was needed.
Date: December 1972
Creator: Guertin, James
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Shubnikov-de Haas Effect Under Uniaxial Stress: A New Method for Determining Deformation Potentials and Band Structure Information in Semiconductors

Description: The problem with which this investigation is concerned is that of demonstrating the applicability of a particular theory and technique to two materials of different band structure, InSb and HgSe, and in doing so, determining the deformation potentials of these materials. The theory used in this investigation predicts an inversion-asymmetry splitting and an anisotropy of the Fermi surface under uniaxial stress. No previous studies have ever verified the existence of an anisotropy of the Fermi su… more
Date: December 1972
Creator: Hathcox, Kyle Lee
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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
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Microwave Properties of Liquids and Solids, Using a Resonant Microwave Cavity as a Probe

Description: The frequency shifts and Q changes of a resonant microwave cavity were utilized as a basis for determining microwave properties of solids and liquids. The method employed consisted of varying the depth of penetration of a cylindrical sample of the material into a cavity operating in the TM0 1 0 Mode. The liquid samples were contained in a thin-walled quartz tube. The perturbation of the cavity was achieved by advancing the sample into the cavity along the symmetry axis by employing a micrometer… more
Date: May 1974
Creator: Hong, Ki H.
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A Classical Theory of the Dielectric Susceptibility of Anharmonic Crystals

Description: An expression for the dielectric susceptibility tensor of a cubic ionic crystal has been derived using the classical Liouville operator. The effect of cubic anharmonic forces is included as a perturbation on the harmonic crystal solution, and a series expansion for the dielectric susceptibility is developed. The most important terms in the series are identified and summed, yielding an expression for the complex susceptibility with an anharmonic contribution which is linearly dependent on temper… more
Date: May 1976
Creator: Kennedy, Howard V.
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Theoretical Cross Section for Light Scattering from Superfluid Helium-4

Description: The finite lifetime of the bound roton pair is included in the theoretical light scattering cross section to explain the shape of the peak in the observed Raman light scattering cross section in He II. A model Hamiltonian is used to describe interactions between quasiparticles for the helium system. The equation of motion for the bound roton pair state, which is taken to be a collective mode of quasiparticle pairs, is solved. The cross section for light scattering is then derived using Fermi's … more
Date: May 1976
Creator: Latham, W. Peters, Jr., 1948-2016.
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K-Shell Ionization Cross Sections of Selected Elements from Fe to As for Proton Bombardment from 0.5 to 2.0 MeV

Description: The problem with which this investigation is concerned is that of making experimental measurements of proton-induced K-shell x-ray production cross sections and to study the dependence of these cross sections upon the energy of the incident proton. The measurements were made by detection of the characteristic x-rays emitted as a consequence of the ionization of the K-shell of the atom. The method for relating this characteristic x-ray emission to the x-ray production cross section is discussed … more
Date: December 1973
Creator: Lear, Richard Dean
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A Study of L-Shell X-Ray Production Cross Sections Due to [Hydrogen-1], [Helium-4], and [Lithium-7] Ion Bombardment of Selected Thin Rare Earth and ₈₂Pb Targets

Description: Thin target L-Shell x-ray production cross sections for protons incident on ₆₂Sm and ₇₀Yb in the energy range of 0.3 to 2.4 MeV/amu, alpha particles incident on ₆₂Sm, ₇₀Yb, and ₈₂Pb in the energy range of 0.15 to 4.8 MeV/amu, and lithium ions incident on ₅₈Ce, ₆₀Nd, ₆₂Sm, ₆₆Dy, ₆₇Ho, ₇₀Yb, and ₈₂Pb in the energy range of 0.8 to 4.4 MeV/amu have been measured. The cross section data have been compared to the planewave Born approximation (PWBA) and the PWBA modified to include binding energy and … more
Date: May 1978
Creator: Light, Glenn Michael
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Cross Section Measurements in Praseodymium-141 as a Function of Neutron Bombarding Energy

Description: 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.
Date: May 1971
Creator: Marsh, Stephen Addison
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Microwave Line Widths of the Asymmetric Top Formic Acid Molecule

Description: This work consisted of an experimental investigation of the formic acid (HCOOH) molecule's rotational spectrum. Measurements of line widths were obtained for J = 5, 12, 13, 19, and 20 for a pressure range from 1 to 10 microns. A linear behavior between Av and p was observed as predicted by theory. The line width parameter Avp was observed to depend on the quantum number J. Hard sphere collision diameters b1 were calculated using the obtained AvP values. These deduced hard sphere values were fo… more
Date: August 1974
Creator: Maynard, Wayne R.
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Partner: UNT Libraries
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