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open access

Advanced far infrared blocked impurity band detectors based on germanium liquid phase epitaxy

Description: This research has shown that epilayers with residual impurity concentrations of 5 x 10{sup 13} cm{sup {minus}3} can be grown by producing the purest Pb available in the world. These epilayers have extremely low minority acceptor concentrations, which is ideal for fabrication of IR absorbing layers. The Pb LPE growth of Ge also has the advantageous property of gettering Cu from the epilayer and the substrate. Epilayers have been grown with intentional Sb doping for IR absorption on lightly doped… more
Date: May 1, 1998
Creator: Olsen, C.S.
open access

The applicability of certain Monte Carlo methods to the analysis of interacting polymers

Description: The authors consider polymers, modeled as self-avoiding walks with interactions on a hexagonal lattice, and examine the applicability of certain Monte Carlo methods for estimating their mean properties at equilibrium. Specifically, the authors use the pivoting algorithm of Madras and Sokal and Metroplis rejection to locate the phase transition, which is known to occur at {beta}{sub crit} {approx} 0.99, and to recalculate the known value of the critical exponent {nu} {approx} 0.58 of the system … more
Date: May 1, 1998
Creator: Krapp, D.M. Jr.
open access

Applications of electrochemically-modulated liquid chromatography (EMLC): Separations of aromatic amino acids and polycyclic aromatic hydrocarbons

Description: The research in this thesis explores the separation capabilities of a new technique termed electrochemically-modulated liquid chromatography (EMLC). The thesis begins with a general introduction section which provides a literature review of this technique as well as a brief background discussion of the two research projects in each of the next two chapters. The two papers which follow investigate the application of EMLC to the separation of a mixture of aromatic amino acids and of a mixture of … more
Date: March 27, 1998
Creator: Deng, L.
open access

A Compton camera for spectroscopic imaging from 100 keV to 1 MeV

Description: A review of spectroscopic imaging issues, applications, and technology is presented. Compton cameras based on solid state semiconductor detectors stands out as the best system for the nondestructive assay of special nuclear materials. A camera for this application has been designed based on an efficient specific purpose Monte Carlo code developed for this project. Preliminary experiments have been performed which demonstrate the validity of the Compton camera concept and the accuracy of the cod… more
Date: December 31, 1998
Creator: Earnhart, J. R. D.
open access

Construction of Effective Electromagnetic Currents for Two-Body Quasipotential Equations

Description: A systematic algebraic approach for the construction of effective electro-magnetic currents consistent with relativistic two-body quasipotential equations is presented. This approach generalizes the Mandelstam formalism and applies it to a generic quasipotential reduction method. The use of Ward-Takahashi identities for the effective currents guarantees conservation of current matrix elements involving any combination of bound and scattering states. This approach is shown to reproduce previous … more
Date: September 1, 1998
Creator: Krioukov, Dmitri
open access

Control of nonlinear systems using periodic parametric perturbations with application to a reversed field pinch

Description: In this thesis, the possibility of controlling low- and high-dimensional chaotic systems by periodically driving an accessible system parameter is examined. This method has been carried out on several numerical systems and the MST Reversed Field Pinch. The numerical systems investigated include the logistic equation, the Lorenz equations, the Roessler equations, a coupled lattice of logistic equations, a coupled lattice of Lorenz equations, the Yoshida equations, which model tearing mode fluctu… more
Date: June 1, 1998
Creator: Mirus, Kevin A.
open access

Controlling fluctuations and transport in the reversed field pinch with edge current drive and plasma biasing

Description: Two techniques are employed in the Madison Symmetric Torus (MST) to test and control different aspects of fluctuation induced transport in the Reversed Field Pinch (RFP). Auxiliary edge currents are driven along the magnetic field to modify magnetic fluctuations, and the particle and energy transport associated with them. In addition, strong edge flows are produced by plasma biasing. Their effect on electrostatic fluctuations and the associated particle losses is studied. Both techniques are ac… more
Date: September 1, 1998
Creator: Craig, D.J.G.
open access

Effect of uniaxial stress on gallium, beryllium, and copper-doped germanium hole population inversion lasers

Description: The effects of stress on germanium lasers doped with single, double, and triple acceptors have been investigated. The results can be explained quantitatively with theoretical calculations and can be attributed to specific changes in the energy levels of acceptors in germanium under stress. In contrast to previous measurements, gallium-doped Ge crystals show a decrease in lasing upon uniaxial stress. The decrease seen here is attributed to the decrease in heavy hole effective mass upon applicati… more
Date: May 1998
Creator: Chamberlin, D. R.
open access

Effects of low-temperature catalytic pretreatments on coal structure and reactivity in liquefaction. Final technical report, Volume 1 - effects of solvents, catalysts and temperature conditions on conversion and structural changes of low-rank coals

Description: The main objectives of this project were to study the effects of low-temperature pretreatments on coal structure and their impacts on subsequent liquefaction. The effects of pretreatment temperatures, catalyst type, coal rank, and influence of solvent were examined. Specific objectives were to identify the basic changes in coal structure induced by catalytic and thermal pretreatments, and to determine the reactivity of the catalytically and thermally treated coals for liquefaction. In the origi… more
Date: January 1, 1998
Creator: Huang, Lili; Schobert, H.H. & Song, Chunshan
open access

Effects of pore fluids in the subsurface on ultrasonic wave propagation

Description: This thesis investigates ultrasonic wave propagation in unconsolidated sands in the presence of different pore fluids. Laboratory experiments have been conducted in the sub-MHz range using quartz sand fully saturated with one or two liquids. Elastic wave propagation in unconsolidated granular material is computed with different numerical models: in one-dimension a scattering model based on an analytical propagator solution, in two dimensions a numerical approach using the boundary integral equa… more
Date: May 1, 1998
Creator: Seifert, P.K.
open access

Fourier transform photoelectron diffraction and its application to molecular orbitals and surface structure

Description: Photoemission intensities from the molecular orbitals of c(2x2)CO/Pt(111) over a wide photon energy range were measured and analyzed by the same methods developed for structural studies using core levels. The 4{sigma} orbital center of gravity is found to be concentrated between the C and O atoms, while that of the 5{sigma} orbital lies between the C atom and the Pt surface. The C 1s photoelectron diffraction was used to determine the adsorption geometry. The earlier ambiguity that multiple sca… more
Date: November 30, 1998
Creator: Zhou, Xin
open access

Gas Phase Chromatography of some Group 4, 5, and 6 Halides

Description: Gas phase chromatography using The Heavy Element Volatility Instrument (HEVI) and the On Line Gas Apparatus (OLGA III) was used to determine volatilities of ZrBr{sub 4}, HfBr{sub 4}, RfBr{sub 4}, NbBr{sub 5}, TaOBr{sub 3}, HaCl{sub 5}, WBr{sub 6}, FrBr, and BiBr{sub 3}. Short-lived isotopes of Zr, Hf, Rf, Nb, Ta, Ha, W, and Bi were produced via compound nucleus reactions at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory and transported to the experimental apparatus using a He ga… more
Date: October 1, 1998
Creator: Sylwester, Eric Robert
open access

The influence of surface topography on the forming friction of automotive aluminum sheet

Description: Interest in utilizing aluminum alloys in automobiles has increased in recent years as a result of the desire to lower automobile weight and, consequently, increase fuel economy. While aluminum alloy use in cast parts has increased, outer body panel applications are still being investigated. The industry is interested in improving the formability of these sheet alloys by a combination of alloy design and processing. A different avenue of improving the formability of these alloys may be through p… more
Date: May 1, 1998
Creator: Kramer, P. A.
open access

Inner-shell photoionized x-ray lasers

Description: The inner-shell photoionized x-ray lasing scheme is an attractive method for achieving x-ray lasing at short wavelengths, via population inversion following inner-shell photoionization (ISPI). This scheme promises both a short wavelength and a short pulse source of coherent x rays with high average power. In this dissertation a very complete study of the ISPI x-ray laser scheme is done concerning target structure, filter design and lasant medium. An investigation of the rapid rise time of x-ray… more
Date: June 1, 1998
Creator: Moon, S. J.
open access

Interfacial characterization and analytical applications of chemically-modified surfaces

Description: The goal of this work is to explore several new strategies and approaches to the surface modification and the microscopic characterization of interfaces in the areas mainly targeting sensor technologies that are of interest to environmental control or monitoring, and scanning probe microscopies techniques that can monitor interfacial chemical reactions in real time. Centered on the main theme, four specific topics are presented as four chapters in this dissertation following the general introdu… more
Date: February 23, 1998
Creator: Wang, J.
open access

Laser-plasma interactions relevant to Inertial Confinement Fusion

Description: Research into laser-driven inertial confinement fusion is now entering a critical juncture with the construction of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL). Many of the remaining unanswered questions concerning NIF involve interactions between lasers and plasmas. With the eventual goal of fusion power in mind, laser-plasma interactions relevant to laser fusion schemes is an important topic in need of further research. This work experimentally addres… more
Date: November 2, 1998
Creator: Wharton, Kenneth Bradford
open access

Markov transitions and the propagation of chaos

Description: The propagation of chaos is a central concept of kinetic theory that serves to relate the equations of Boltzmann and Vlasov to the dynamics of many-particle systems. Propagation of chaos means that molecular chaos, i.e., the stochastic independence of two random particles in a many-particle system, persists in time, as the number of particles tends to infinity. We establish a necessary and sufficient condition for a family of general n-particle Markov processes to propagate chaos. This conditio… more
Date: December 1, 1998
Creator: Gottlieb, A.
open access

Measurement of time dependent B{sub d}{sup 0} {bar B}{sub d}{sup 0} mixing parameter using opposite side lepton and D* meson in p{bar p} collisions at {radical}s = 1.8 TeV

Description: This thesis presents the results from the investigation of time dependent B{sub d}{sup 0} {bar B}{sub d}{sup 0} mixing in B {yields} lepton X, B{sub d}{sup 0} {yields} D*{sup -} {yields} {bar D}{sup 0} {pi}{sup -}, {bar D}{sup 0} {yields} K{sup +} {pi}{sup -} channel in p{bar p} collisions at {radical}s = 1.8 TeV using 110 pb{sup -1} data collected with the CDF detector at the Fermilab Tevatron Collider. The {bar D}{sup 0} vertex is reconstructed. The B{sub d}{sup 0} decay length is estimated u… more
Date: January 13, 1998
Creator: Vandenbrink, S.C.
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