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open access

A search for sterile neutrinos in MINOS

Description: MINOS, the Main Injector Neutrino Oscillation Search, is a long baseline neutrino oscillation experiment based at Fermilab National Accelerator Laboratory. The experiment uses a neutrino beam, which is measured 1 km downstream from its origin in the Near detector at Fermilab and then 735 km later in the Far detector at the Soudan mine. By comparing these two measurements, MINOS can attain a very high precision for parameters in the atmospheric sector of neutrino oscillations. In addition to pre… more
Date: December 1, 2007
Creator: Osiecki, Thomas Henry
Partner: UNT Libraries Government Documents Department
open access

Measurements of Direct CP Violation, CPT Symmetry, and Other Parameters in the Neutral Kaon System

Description: The authors present precision measurements of the direct CP violation parameter, Re({epsilon}{prime}/{epsilon}), the kaon parameters, {Delta}m and {tau}{sub S}, and the CPT tests, {phi}{sub {+-}} and {Delta}{phi}, in neutral kaon decays. These results are based on the full dataset collected by the KTeV experiment at Fermi National Accelerator Laboratory during 1996, 1997, and 1999. This dataset contains {approx} 15 million K {yields} {pi}{sup 0}{pi}{sup 0} decays and {approx} 69 million K {yiel… more
Date: December 1, 2007
Creator: Worcester, Elizabeth Turner
Partner: UNT Libraries Government Documents Department
open access

Processing and Protection of Rare Earth Permanent Magnet Particulate for Bonded Magnet Applications

Description: Rapid solidification of novel mixed rare earth-iron-boron, MRE{sub 2}Fe{sub 14}B (MRE = Nd, Y, Dy; currently), magnet alloys via high pressure gas atomization (HPGA) have produced similar properties and structures as closely related alloys produced by melt spinning (MS) at low wheel speeds. Recent additions of titanium carbide and zirconium to the permanent magnet (PM) alloy design in HPGA powder (using He atomization gas) have made it possible to achieve highly refined microstructures with mag… more
Date: December 1, 2007
Creator: Sokolowski, Peter Kelly
Partner: UNT Libraries Government Documents Department
open access

M5Si3(M=Ti, Nb, Mo) Based Transition-Metal Silicides for High Temperature Applications

Description: Transition metal silicides are being considered for future engine turbine components at temperatures up to 1600 C. Although significant improvement in high temperature strength, room temperature fracture toughness has been realized in the past decade, further improvement in oxidation resistance is needed. Oxidation mechanism of Ti{sub 5}Si{sub 3}-based alloys was investigated. Oxidation behavior of Ti{sub 5}Si{sub 3}-based alloy strongly depends on the atmosphere. Presence of Nitrogen alters th… more
Date: December 1, 2007
Creator: Tang, Zhihong
Partner: UNT Libraries Government Documents Department
open access

A measurement of the top quark mass in 1.96 TeV proton-antiproton collisions using a novel matrix element method

Description: A measurement of the top quark mass in t{bar t} {yields} l + jets candidate events, obtained from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector, is presented. The measurement approach is that of a matrix element method. For each candidate event, a two dimensional likelihood is calculated in the top pole mass and a constant scale factor, 'JES', where JES multiplies the input particle jet momenta and is designed to account for the systematic uncer… more
Date: December 1, 2007
Creator: Freeman, John C.
Partner: UNT Libraries Government Documents Department
open access

Analysis of Protein-RNA and Protein-Peptide Interactions in Equine Infectious Anemia

Description: Macromolecular interactions are essential for virtually all cellular functions including signal transduction processes, metabolic processes, regulation of gene expression and immune responses. This dissertation focuses on the characterization of two important macromolecular interactions involved in the relationship between Equine Infectious Anemia Virus (EIAV) and its host cell in horse: (1) the interaction between the EIAV Rev protein and its binding site, the Rev-responsive element (RRE) and … more
Date: December 1, 2007
Creator: Lee, Jae-Hyung
Partner: UNT Libraries Government Documents Department
open access

Control of Laser Plasma Based Accelerators up to 1 GeV

Description: This dissertation documents the development of a broadband electron spectrometer (ESM) for GeV class Laser Wakefield Accelerators (LWFA), the production of high quality GeV electron beams (e-beams) for the first time in a LWFA by using a capillary discharge guide (CDG), and a statistical analysis of CDG-LWFAs. An ESM specialized for CDG-LWFAs with an unprecedented wide momentum acceptance, from 0.01 to 1.1 GeV in a single shot, has been developed. Simultaneous measurement of e-beam spectra and … more
Date: December 3, 2007
Creator: Nakamura, Kei
Partner: UNT Libraries Government Documents Department
open access

Measurements of CP asymmetries and branching fractions of two-body charmless decays of B^0 and B^0_s mesons

Description: The thesis is organized as follows: Chapter 1 describes the theoretical framework of non-leptonic B{sub (s)}{sup 0} {yields} H{sup +}h{prime}{sup -} decays, with a simple overview of the CP violation mechanism within the Standard Model and of the most used phenomenological approaches in the evaluation of strong interaction contributions. The chapter contains also a review of the theoretical expectations and the current experimental measurements along with a discussion about the importance of st… more
Date: December 1, 2007
Creator: Morello, Michael Joseph & /Pisa, Scuola Normale Superiore
Partner: UNT Libraries Government Documents Department
open access

An atmospheric muon neutrino disappearance measurement with the MINOS far detector

Description: It is now widely accepted that the Standard Model assumption of massless neutrinos is wrong, due primarily to the observation of solar and atmospheric neutrino flavor oscillations by a small number of convincing experiments. The MINOS Far Detector, capable of observing both the outgoing lepton and associated showering products of a neutrino interaction, provides an excellent opportunity to independently search for an oscillation signature in atmospheric neutrinos. To this end, a MINOS data set … more
Date: December 1, 2007
Creator: Gogos, Jeremy Peter
Partner: UNT Libraries Government Documents Department
open access

Mechanisms Associated with Rumpling of Pt-Modified Beta-NiAl Coatings

Description: The formation of surface undulations (i.e. rumpling) at the bond coat/thermally grown oxide (TGO) interface has been shown to cause failure by spallation of the ceramic top coat in aero-turbine systems. Many mechanisms have been proposed concerning the cause of these surface distortions; however, there is little agreement on what may be the dominating cause of the rumpling behavior. Of there mechanisms, the reversible phase transformation from a cubic {beta}-NiAl structure to a face centered te… more
Date: December 1, 2007
Creator: Henderkott, Joseph Peter
Partner: UNT Libraries Government Documents Department
open access

Sum Frequency Generation Vibrational Spectroscopy Studies on ModelPeptide Adsorption at the Hydrophobic Solid-Water and HydrophilicSolid-Water Interfaces

Description: Sum frequency generation (SFG) vibrational spectroscopy has been used to study the interfacial structure of several polypeptides and amino acids adsorbed to hydrophobic and hydrophilic surfaces under a variety of experimental conditions. Peptide sequence, peptide chain length, peptide hydrophobicity, peptide side-chain type, surface hydrophobicity, and solution ionic strength all affect an adsorbed peptide's interfacial structure. Herein, it is demonstrated that with the choice of simple, model… more
Date: December 19, 2007
Creator: York, Roger L.
Partner: UNT Libraries Government Documents Department
open access

The Study of Electromagnetic Wave Propogation in Photonic Crystals Via Planewave Based Transfer (Scattering) Matrix Method with Active Gain Material Applications

Description: In this dissertation, a set of numerical simulation tools are developed under previous work to efficiently and accurately study one-dimensional (1D), two-dimensional(2D), 2D slab and three-dimensional (3D) photonic crystal structures and their defects effects by means of spectrum (transmission, reflection, absorption), band structure (dispersion relation), and electric and/or magnetic fields distribution (mode profiles). Furthermore, the lasing property and spontaneous emission behaviors are st… more
Date: December 1, 2007
Creator: LI, Ming
Partner: UNT Libraries Government Documents Department
open access

Electrospray Ionization Mass Spectrometry: From Cluster Ions to Toxic metal Ions in Biology

Description: This dissertation focused on using electrospray ionization mass spectrometry to study cluster ions and toxic metal ions in biology. In Chapter 2, it was shown that primary, secondary and quarternary amines exhibit different clustering characteristics under identical instrument conditions. Carbon chain length also played a role in cluster ion formation. In Chapters 3 and 4, the effects of solvent types/ratios and various instrumental parameters on cluster ion formation were examined. It was foun… more
Date: December 1, 2007
Creator: Lentz, Nicholas B.
Partner: UNT Libraries Government Documents Department
open access

A Search for the Higgs Boson in its Associated Production with a W Vector Boson in p anti-p Collisions at s**(1/2) = 1.96-TeV

Description: We present the results of a search for the Standard Model Higgs boson in its associated production with a W vector boson in p{bar p} collisions at {radical}s = 1.96 TeV using the complete Run IIA dataset with an integrated luminosity of 1.04 fb{sup -1} collected by the D0 experiment. The salient features of this analysis are the extended geometric acceptance by including the pseudorapidity covered by the end cap calorimeter, optimization in b-tagging and event selection criteria. We observe ver… more
Date: December 1, 2007
Creator: Kaushik, Venkatesh S. & /Texas U., Arlington
Partner: UNT Libraries Government Documents Department
open access

NMR Studies of the Vanadium Spin Dynamics and Spin Structure in LiV2O4, CaV2O4, and (LixV1-x)3BO5 (x is almost equal to 0.33, 0.40)

Description: Strong electron correlation is believed to be an essential and unifying factor in diverse properties of condensed matter systems. Ground states that can arise due to electron correlation effects include Mott insulators, heavy fermion, ferromagnetism and antiferromagnetism, spin glasses, and high-temperature superconductivity. The electronic systems in transition metal oxide compounds are often highly correlated. In this thesis, the author presents experimental studies on three strongly correlat… more
Date: December 1, 2007
Creator: Zong, Xiaopeng
Partner: UNT Libraries Government Documents Department
open access

High-Pressure Catalytic Reactions of C6 Hydrocarbons on PlatinumSingle-Crystals and nanoparticles: A Sum Frequency Generation VibrationalSpectroscopic and Kinetic Study

Description: Catalytic reactions of cyclohexene, benzene, n-hexane, 2-methylpentane, 3-methylpentane, and 1-hexene on platinum catalysts were monitored in situ via sum frequency generation (SFG) vibrational spectroscopy and gas chromatography (GC). SFG is a surface specific vibrational spectroscopic tool capable of monitoring submonolayer coverages under reaction conditions without gas-phase interference. SFG was used to identify the surface intermediates present during catalytic processes on Pt(111) and Pt… more
Date: December 19, 2007
Creator: Bratlie, Kaitlin
Partner: UNT Libraries Government Documents Department
open access

Pattern Formation and Growth Kinetics in Eutectic Systems

Description: Growth patterns during liquid/solid phase transformation are governed by simultaneous effects of heat and mass transfer mechanisms, creation of new interfaces, jump of the crystallization units from liquid to solid and their rearrangement in the solid matrix. To examine how the above processes influence the scale of microstructure, two eutectic systems are chosen for the study: a polymeric system polyethylene glycol-p-dibromobenzene (PEG-DBBZ) and a simple molecular system succinonitrile (SCN)-… more
Date: December 1, 2007
Creator: Teng, Jing
Partner: UNT Libraries Government Documents Department
open access

Advanced Branching Control and Characterization of Inorganic Semiconducting Nanocrystals

Description: The ability to finely tune the size and shape of inorganic semiconducting nanocrystals is an area of great interest, as the more control one has, the more applications will be possible for their use. The first two basic shapes develped in nanocrystals were the sphere and the anistropic nanorod. the II_VI materials being used such as Cadmium Selenide (CdSe) and Cadmium Telluride (CdTe), exhibit polytypism, which allows them to form in either the hexagonally packed wurtzite or cubically packed zi… more
Date: December 31, 2007
Creator: Hughes, Steven Michael
Partner: UNT Libraries Government Documents Department
open access

Development of Carbon Based optically Transparent Electrodes from Pyrolyzed Photoresist for the Investigation of Phenomena at Electrified Carbon-Solution Interfaces

Description: The work presented herein describes a fundamental investigations of carbon as electrode material by using the pyrolysis of photoresist to create an optically transparent material. The development of these carbon-based optically transparent electrodes (C-OTEs) enables investigations of molecular interactions within the electrical double layer, processes that are central to a wide range of important phenomena, including the impact of changes in the surface charge density on adsorption. The electr… more
Date: December 1, 2007
Creator: Donner, Sebastian
Partner: UNT Libraries Government Documents Department
open access

Controlled Dissolution of Surface Layers for Elemental Analysis by Inductively Coupled Plasma-Mass Spectrometry

Description: Determining the composition of thin layers is increasingly important for a variety of industrial materials such as adhesives, coatings and microelectronics. Secondary ion mass spectrometry (SIMS), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), glow discharge optical emission spectroscopy (GDOES), glow discharge mass spectrometry (GDMS), and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) are some of the techniques that are currently employed f… more
Date: December 1, 2007
Creator: Lorge, Susan Elizabeth
Partner: UNT Libraries Government Documents Department
open access

Improving Hardness and Toughness of Boride Composites Based on AIMgB14

Description: The search for new super-hard materials has usually focused on strongly bonded, highly symmetric crystal structures similar to diamond. The two hardest single-phase materials, diamond and cubic boron nitride (cBN), are metastable, and both must be produced at high temperatures and pressures, which makes their production costly. In 2000, a superhard composite based on a low-symmetry, boron-rich compound was reported. Since then, many advances have been made in the study of this AlMgB{sub 14}-TiB… more
Date: December 1, 2007
Creator: Peters, Justin Steven
Partner: UNT Libraries Government Documents Department
open access

Search for Admixture of Scalar Top in the ttbar Lepton+Jets Final State at s**(1/2) = 1.96 TeV

Description: A search for pair production of scalar top (stop) quarks has been performed in the lepton+jets channel in {approx} 1 fb{sup -1} of data at the D0 experiment. Kinematic differences between {tilde t}{sub 1}{bar {tilde t}}{sub 1} and the dominant t{bar t} process are used to separate the two reactions. For stop-quark masses of 145-175 GeV, and chargino masses of 105-135 GeV, to which the stop quarks decay ({tilde t}{sub 1} {yields} {tilde {chi}}{sub 1}{sup +}b), we obtain upper limits on the {tild… more
Date: December 1, 2007
Creator: Park, Su-Jung
Partner: UNT Libraries Government Documents Department
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