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  Partner: UNT Libraries
 Degree Discipline: Physics
 Collection: UNT Theses and Dissertations
Decoherence, Master Equation for Open Quantum Systems, and the Subordination Theory

Decoherence, Master Equation for Open Quantum Systems, and the Subordination Theory

Date: August 2005
Creator: Giraldi, Filippo
Description: This thesis addresses the problem of a form of anomalous decoherence that sheds light into the spectroscopy of blinking quantum dots. The system studied is a two-state system, interacting with an external environment that has the effect of establishing an interaction between the two states, via a coherence generating coupling, called inphasing. The collisions with the environment produce also decoherence, named dephasing. Decoherence is interpreted as the entanglement of the coherent superposition of these two states with the environment. The joint action of inphasing and dephasing generates a Markov master equation statistically equivalent to a random walker jumping from one state to the other. This model can be used to describe intermittent fluorescence, as a sequence of "light on" and "light off" states. The experiments on blinking quantum dots indicate that the sojourn times are distributed with an inverse power law. Thus, a proposal to turn the model for Poisson fluorescence intermittency into a model for non-Poisson fluorescence intermittency is made. The collision-like interaction of the two-state system with the environment is assumed to takes place at random times rather than at regular times. The time distance between one collision and the next is given by a distribution, called the ...
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Design and Construction of a Positive Radio-Frequency Ion Source for the Production of Negative Ions

Design and Construction of a Positive Radio-Frequency Ion Source for the Production of Negative Ions

Date: August 1958
Creator: Thompson, B. Cecil
Description: 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.
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Design and Testing of a Coincidence System

Design and Testing of a Coincidence System

Date: January 1961
Creator: Barnes, W. L., Jr.
Description: This paper is concerned with the design, testing and performance of a coincidence system, the proposed North Texas State College accelerator.
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Design and Testing of a Corona Column and a Closed Gas Distribution System for a Tandem Van de Graaff Voltage Generator

Design and Testing of a Corona Column and a Closed Gas Distribution System for a Tandem Van de Graaff Voltage Generator

Date: June 1962
Creator: Gray, Thomas Jack
Description: The purpose of this study had been to design and test a corona column and an insulating gas distribution system for a small tandem Van de Graaff. The intent of this paper is to describe the gas handling system and to compare experimentally the effects of corona electrode shape on the corona current carried between adjacent sections of the column.
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Design and Testing of a Positive Ion Accelerator and Necessary Vacuum System

Design and Testing of a Positive Ion Accelerator and Necessary Vacuum System

Date: August 1953
Creator: McKay, Vern A.
Description: This thesis is a study of the design and testing of a positive ion accelerator and necessary vacuum system.
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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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Dielectric Relaxation of Aqueous Solutions at Microwave Frequencies for 3[less than or equal to]f[less than or equal to]35 GHz. Using a Loaded Microwave Cavity Operating in the TM010 Mode

Dielectric Relaxation of Aqueous Solutions at Microwave Frequencies for 3[less than or equal to]f[less than or equal to]35 GHz. Using a Loaded Microwave Cavity Operating in the TM010 Mode

Date: August 1994
Creator: Wang, Henry F. S. (Henry Fu-Sen)
Description: The frequency dependence and temperature dependence of the complex dielectric constant of water is of great interest. The temperature dependence of the physical properties of water given in the literature, specific heat, thermal conductivity, electric conductivity, pH, etc. are compared to the a. c. (microwave) and d. c. conductivity of water with a variety of concentration of different substances such as HC1, NaCl, HaS04, etc. When each of these properties is plotted versus inverse absolute temperature, it can be seen that each sample shows "transition temperatures". In this work, Slater's perturbation equations for a resonant microwave cavity were used to analyze the experimental results for the microwave data.
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