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  Partner: UNT Libraries
 Degree Discipline: Physics
 Collection: UNT Theses and Dissertations
A Determination of the Bothe Depression Factor for Discs in Water

A Determination of the Bothe Depression Factor for Discs in Water

Date: August 1950
Creator: Patton, Bob
Description: 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.
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A Determination of the Fine Structure Constant Using Precision Measurements of Helium Fine Structure

A Determination of the Fine Structure Constant Using Precision Measurements of Helium Fine Structure

Date: August 2010
Creator: Smiciklas, Marc
Description: Spectroscopic measurements of the helium atom are performed to high precision using an atomic beam apparatus and electro-optic laser techniques. These measurements, in addition to serving as a test of helium theory, also provide a new determination of the fine structure constant α. An apparatus was designed and built to overcome limitations encountered in a previous experiment. Not only did this allow an improved level of precision but also enabled new consistency checks, including an extremely useful measurement in 3He. I discuss the details of the experimental setup along with the major changes and improvements. A new value for the J = 0 to 2 fine structure interval in the 23P state of 4He is measured to be 31 908 131.25(30) kHz. The 300 Hz precision of this result represents an improvement over previous results by more than a factor of three. Combined with the latest theoretical calculations, this yields a new determination of α with better than 5 ppb uncertainty, α-1 = 137.035 999 55(64).
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A Deuterium-Deuterium Type Neutron Source

A Deuterium-Deuterium Type Neutron Source

Date: 1951
Creator: Windham, Pat M.
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.
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The Dielectric Constant of Galvinoxyl

The Dielectric Constant of Galvinoxyl

Date: May 1968
Creator: Mizell, Michael E.
Description: The molecules in many substances are know to undergo at characteristic temperatures a change in their rotational freedom in the solid state, signifying either a change in structure of the material of the onset of limited rotation of the molecule about some symmetry axis. The purpose of this research was to determine from dielectric constant measurements over the 100°K-420°K temperature range whether or not the organic free radical galvinoxyl and its diamagnetic parent molecule, dihydroxydiphenylmethane, undergo any such transitions.
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Dipole Moments of Diphenyl Compounds with Conjugated Double Bonds

Dipole Moments of Diphenyl Compounds with Conjugated Double Bonds

Date: 1950
Creator: Spalding, Dan W.
Description: This thesis is a continuation of a study of molecular moments begun by Joseph T. Fielder. In his paper he discussed the theory and the equipment necessary for such a study. It is the purpose of this paper to set forth modifications of his equipment, to present data obtained with this modified equipment, and to interpret this data.
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Dipole Moments of Olefenic Diesters

Dipole Moments of Olefenic Diesters

Date: 1951
Creator: Shipley, Floyd D.
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.
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Dipole Moments of Olefinic Esters

Dipole Moments of Olefinic Esters

Date: 1952
Creator: Poteet, Horace M.
Description: It is the purpose of this thesis to investigate the applicability of the Debye equation to measurements dipole moments of polar compounds in dilute solutions of non-polar solvents more fully than has been done by previous workers at this institution.
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Distribution of Nighttime F-region Molecular Ion Concentrations and 6300 Å Nightglow Morphology

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

Date: December 1970
Creator: Brasher, William Ernest, 1939-
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.
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The Diurnal Variation of Cosmic Radiation

The Diurnal Variation of Cosmic Radiation

Date: August 1965
Creator: Fowler, Brooks C.
Description: The primary purpose of this investigation was to study the diurnal variation of cosmic-ray intensity.
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A dynamic and thermodynamic approach to complexity.

A dynamic and thermodynamic approach to complexity.

Date: August 2003
Creator: Yang, Jin
Description: The problem of establishing the correct approach to complexity is a very hot and crucial issue to which this dissertation gives some contributions. This dissertation considers two main possibilities, one, advocated by Tsallis and co-workers, setting the foundation of complexity on a generalized, non-extensive , form of thermodynamics, and another, proposed by the UNT Center for Nonlinear Science, on complexity as a new condition that, for physical systems, would be equivalent to a state of matter intermediate between dynamics and thermodynamics. In the first part of this dissertation, the concept of Kolmogorov-Sinai entropy is introduced. The Pesin theorem is generalized in the formalism of Tsallis non-extensive thermodynamics. This generalized form of Pesin theorem is used in the study of two major classes of problems, whose prototypes are given by the Manneville and the logistic map respectively. The results of these studies convince us that the approach to complexity must be made along lines different from those of the non-extensive thermodynamics. We have been convinced that the Lévy walk can be used as a prototype model of complexity, as a condition of balance between order and randomness that yields new phenomena such as aging, and multifractality. We reach the conclusions that ...
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