Quantized Hydrodynamics (open access)

Quantized Hydrodynamics

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.
System: The UNT Digital Library
A Decay Scheme for 164 Ho (open access)

A Decay Scheme for 164 Ho

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
System: The UNT Digital Library
Pressure Dependence of Line Widths of Microwave Spectra of Sulphur Dioxide (open access)

Pressure Dependence of Line Widths of Microwave Spectra of Sulphur Dioxide

Measurements of line width parameters for eleven rotational transitions of type (J -- J + 1) of SO2 were made and are reported herein. The line width quantum number (J) trend was obtained. The microwave spectrograph used for these measurements of line width is described. Operational methods to operate the spectrograph are presented and discussed, with particular attention given to how to measure the line width. Suggestions for future avenues of probing this molecule to ascertain the non-uniform behavior of the line width parameter over the quantum number and frequency range are given.
Date: December 1972
Creator: Yang, Wei Han
System: The UNT Digital Library
Measurement of the Atomic-oxygen Concentration under Simulated Upper Atmosphere Conditions (open access)

Measurement of the Atomic-oxygen Concentration under Simulated Upper Atmosphere Conditions

This thesis describes an experimental technique for measuring the atomic-oxygen concentration under simulated upper atmosphere conditions.
Date: January 1970
Creator: Grable, Weliko C.
System: The UNT Digital Library
A Precision Angular Correlation Table and Calculation of Geometrical Correction Factors (open access)

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.
Date: January 1970
Creator: Rowton, Larry James
System: The UNT Digital Library
Cross Section Measurements in Praseodymium-141 as a Function of Neutron Bombarding Energy (open access)

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.
Date: May 1971
Creator: Marsh, Stephen Addison
System: The UNT Digital Library
Phase Shift Determination for Elastic Potential Scattering, Using the IBM 360-50 Computer (open access)

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.
Date: May 1971
Creator: Psencik, James A.
System: The UNT Digital Library
Nuclear Reactions on the Palladium Isotopes (open access)

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.
Date: December 1970
Creator: White, Ronald Lee
System: The UNT Digital Library
A Study of the Decay Levels of 169/Tm69 (open access)

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.
Date: December 1970
Creator: Harris, Robert J.
System: The UNT Digital Library
Carbon Contamination Measurements in Single Silicon Crystals (open access)

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.
Date: December 1970
Creator: Logsdon, Lawrence E.
System: The UNT Digital Library
The Effects of Lead Placement and Sample Shape in the Measurement of Electrical Resistivity (open access)

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.
Date: August 1970
Creator: Stephens, Anthony E.
System: The UNT Digital Library
Investigation of the Uniaxial Stress Dependence of the Effective Mass in N-Type InSb Using the Magnetophonon Effect (open access)

Investigation of the Uniaxial Stress Dependence of the Effective Mass in N-Type InSb Using the Magnetophonon Effect

The magnetophonon effect was used to investigate the uniaxial stress dependence of the effective mass in n-type InSb (indium antimonide).
Date: December 1971
Creator: Alsup, Dale Lynn
System: The UNT Digital Library
Electrical Conductivity in Thin Films (open access)

Electrical Conductivity in Thin Films

This thesis deals with electrical conductivity in thin films. Classical and quantum size effects in conductivity are discussed including some experimental evidence of quantum size effects. The component conductivity along the applied electric field of a thin film in a transverse magnetic field is developed in a density matrix method.
Date: May 1973
Creator: Meyer, Frederick Otto
System: The UNT Digital Library
A Study of Minority Atomic Ion Recombination in the Helium Afterglow (open access)

A Study of Minority Atomic Ion Recombination in the Helium Afterglow

Electron-ion recombination has been under study for many years, but comparisons between theory and experiment have been very difficult, especially for conditions where the ion under evaluation was a minority in concentration. This study describes a direct measurement of the recombination-rate coefficient for the recombination of minority as well as majority ions in the afterglow.
Date: August 1972
Creator: Wells, William E.
System: The UNT Digital Library
Steady-state and Dynamic Probe Characteristics in a Low-density Plasma (open access)

Steady-state and Dynamic Probe Characteristics in a Low-density Plasma

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, and the study of transient ion sheath effects on radio frequency probe admittance.
Date: December 1970
Creator: Bunting, William David
System: The UNT Digital Library
Anisotropic Relaxation Time for Solids with Ellipsoidal Fermi Surfaces (open access)

Anisotropic Relaxation Time for Solids with Ellipsoidal Fermi Surfaces

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.
Date: May 1971
Creator: Fuchser, Troy Denrich
System: The UNT Digital Library
Distribution of Nighttime F-region Molecular Ion Concentrations and 6300 Å Nightglow Morphology (open access)

Distribution of Nighttime F-region Molecular Ion Concentrations and 6300 Å Nightglow Morphology

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-
System: The UNT Digital Library
Magnetomorphic Oscillations in Zinc (open access)

Magnetomorphic Oscillations in Zinc

In making this study it is important to search for ways to enhance and, if possible, make detection of MMO signals simpler in order that this technique for obtaining FS measurements may be extended to other materials. This attempt to improve measurement techniques has resulted in a significant discovery: the eddy-current techniques described in detail in a later section which should allow MMO to be observed and sensitively measured in many additional solids. The second major thrust of the study has been to use the newly discovered eddy-current technique in obtaining the first indisputable observation of MMO in zinc.
Date: August 1970
Creator: Waller, William Marvin
System: The UNT Digital Library
Electron Density and Collision Frequency Studies Using a Resonant Microwave Cavity as a Probe (open access)

Electron Density and Collision Frequency Studies Using a Resonant Microwave Cavity as a Probe

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 signal of the loaded cavity in order to make accurate measurements of the resonant frequency and half-power point frequencies.
Date: May 1973
Creator: Freeman, Ronald Harold
System: The UNT Digital Library
Fluid Spheres in General Relativity: Exact Solutions and Applications to Astrophysics (open access)

Fluid Spheres in General Relativity: Exact Solutions and Applications to Astrophysics

Exact solutions to Einstein's field equations in the presence of matter are presented. A one parameter family of interior solutions for a static fluid is discussed. It is shown that these solutions can be joined to the Schwarzschild exterior, and hence represent fluid spheres of finite radius. Contained within this family is a set of solutions which are gaseous spheres defined by the vanishing of the density at the surface. One such solution yields an analytic expression which corresponds to the asymptotic numerical solution of Oppenheimer and Volkoff for the degenerate neutron gas. These gaseous spheres have ratios of specific heats that lie between one and two in the vicinity of the origin, increasing outward, but remaining less than the velocity of light throughout.
Date: December 1978
Creator: Whitman, Patrick G.
System: The UNT Digital Library
CO₂-Laser Induced Hot Electron Magneto-Transport Effects in n-InSb (open access)

CO₂-Laser Induced Hot Electron Magneto-Transport Effects in n-InSb

The effects of optical heating via infrared free carrier absorption on the electron magneto-transport properties of n-InSb at helium temperatures have been studied for the first time. Oscillatory photoconductivity (OPC) type structure is seen in the photon energy dependence of the transport properties. A C0₂ laser (hω = 115 to 135 meV) was used as the optical source. Concentrations between 1 x 10¹⁵ cm⁻³ and 2 x 10¹⁶ cm⁻³ were studied. The conclusions of this study are that the energy relaxation of high energy photoexcited electrons, generated by free carrier absorption of C0₂ laser radiation in degenerate n-InSb at liquid helium temperatures, is by emission of a maximum number of optical phonons, and that this relaxation mechanism produces OPC type structure in the photon energy dependence of the electron temperature of the conduction band electron gas. This structure is seen, therefore, in the transport properties of the sample, including the Shubnikovde Haas effect, the effective absorption coefficient, and the photoconductivity (mobility) response (lower concentrations only). In addition, the highest concentration studied, nₑ = ~2 x 10¹⁶ cm⁻³, sets an experimental lower limit on the concentration at which electron-electron scattering will become the dominant energy relaxation mechanism for the photoexcited electrons, …
Date: August 1979
Creator: Moore, Bradley T.
System: The UNT Digital Library
Line Width Parameters and Center Frequency Shifts in the Rotational Spectrum of Methyl Cyanide (open access)

Line Width Parameters and Center Frequency Shifts in the Rotational Spectrum of Methyl Cyanide

Measurement of the line width parameters of a molecule is of interest because collision diameters can be calculated from them. This gives an effective size of the molecule when it is involved in interactions with other molecules. Further, specific types of interactions can be inferred from detailed information about the dependence of the line width upon pressure. In this paper, an experiment for measuring line width parameters for methyl cyanide is described and the results of the experiment are analyzed. This investigation was successful in obtaining precise values for the line width parameter for the J-J' = 0-1, J-J'= 1-2, and J-J' = 2-3 transitions of methyl cyanide which agree with experimental values of other researchers where available. It was found that standing waves were the dominant effect in the measurement of center frequency shift.
Date: May 1978
Creator: Swindle, David L.
System: The UNT Digital Library
Inversion-Asymmetry Splitting of the Conduction Band in N-Type Indium Antimonide (open access)

Inversion-Asymmetry Splitting of the Conduction Band in N-Type Indium Antimonide

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 the Fermi surfaces of InSb are nearly spherical at low concentration. It was also shown that the Fermi surface of a high concentration sample of InAs is also nearly spherical. The advantages of using the magnetic field modulation and phase sensitive detection techniques in determining the beats are given. The simple, classical beating-effects model is able to explain the experimental beating effect data in InSb. The computer programs used to obtain the theoretical values of the beat nodal position, SdH frequencies, average frequency, the Fermi surface contours, and the energy eigenvalues are given.
Date: December 1976
Creator: Bajaj, Bhushan D.
System: The UNT Digital Library
Formation of Supersaturated Alloys by Ion Implantation and Pulsed-Laser Annealing (open access)

Formation of Supersaturated Alloys by Ion Implantation and Pulsed-Laser Annealing

Supersaturated substitutional alloys formed by ion implantation and rapid liquid-phase epitaxial regrowth induced by pulsed-laser annealing have been studied using Rutherford-backscattering and ion-channeling analysis. A series of impurities (As, Sb, Bi, Ga, In, Fe, Sn, Cu) have been implanted into single-crystal (001) orientation silicon at doses ranging from 1 x 10^15/cm2 to 1 x 10^17/cm2. The samples were subsequently annealed with a Ω-switched ruby laser (energy density ~1.5 J/cm2, pulse duration 15 x 10-9 sec). Ion-channeling analysis shows that laser annealing incorporates the Group III (Ga, In) and Group V (As, Sb, Bi) impurities into substitutional lattice sites at concentrations far in excess of the equilibrium solid solubility. Channeling measurements indicate the silicon crystal is essentially defect free after laser annealing. The maximum Group III and Group V dopant concentrations that can be incorporated into substitutional lattice sites are determined for the present laser-annealing conditions. Dopant profiles have been measured before and after annealing using Rutherford backscattering. These experimental profiles are compared to theoretical model calculations which incorporate both dopant diffusion in liquid silicon and a distribution coefficient (k') from the liquid. It is seen that a distribution coefficient (k') far greater than the equilibrium value (k0) is required for …
Date: August 1979
Creator: Wilson, Syd Robert
System: The UNT Digital Library