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Optically Detected Magnetic Resonance Studies on π-conjugated semiconductor systems

Description: Optically Detected Magnetic Resonance (ODMR) techniques were used to investigate the dynamics of excitons and charge carriers in π-conjugated organic semiconductors. Degradation behavior of the negative spin-1/2 electroluminescence-detected magnetic resonance (ELDMR) was observed in Alq3 devices. The increase in the resonance amplitude implies an increasing bipolaron formation during degradation, which might be the result of growth of charge traps in the device. The same behavior of the negativ… more
Date: December 6, 2011
Creator: Chen, Ying
Partner: UNT Libraries Government Documents Department
open access

Measurement of muon neutrino and antineutrino induced single neutral pion production cross sections

Description: Elucidating the nature of neutrino oscillation continues to be a goal in the vanguard of the efforts of physics experiment. As neutrino oscillation searches seek an increasingly elusive signal, a thorough understanding of the possible backgrounds becomes ever more important. Measurements of neutrino-nucleus interaction cross sections are key to this understanding. Searches for {nu}{sub {mu}} {yields} {nu}{sub e} oscillation - a channel that may yield insight into the vanishingly small mixing pa… more
Date: December 1, 2010
Creator: Anderson, Colin & U., /Yale
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

A Simplified Spherical Harmonic Method for Coupled Electron-Photon Transport Calculations

Description: In this thesis we have developed a simplified spherical harmonic method (SP{sub N} method) and associated efficient solution techniques for 2-D multigroup electron-photon transport calculations. The SP{sub N} method has never before been applied to charged-particle transport. We have performed a first time Fourier analysis of the source iteration scheme and the P{sub 1} diffusion synthetic acceleration (DSA) scheme applied to the 2-D SP{sub N} equations. Our theoretical analyses indicate that t… more
Date: December 1, 1996
Creator: Josef, John A.
Partner: UNT Libraries Government Documents Department
open access

K vacancy production in medium-Z heavy ion collisions

Description: During slow encounters between projectile and target atoms, the electronic atomic wave functions of the two collision partners distort and form molecular orbitals (MOs). K vacancy formation in slow heavy-ion collisions, which occur when electrons are excited out of the 2psigma and 1ssigma MOs, is considered. Experimental work using 200 MeV Kr ions is described. The main interest is the excitation of electrons from the 1ssigma MO. The 1ssigma vacancy production is only observed in very asymmetri… more
Date: December 1, 1975
Creator: Anholt, R.
Partner: UNT Libraries Government Documents Department
open access

Measurement of direct CP violation in b -> scc and b -> dcc quark transitions using B+ -> J/psiK+ and B+ -> J/psi pi+ decays

Description: This thesis describes the measurement of the direct CP violation in the b {yields} sc{bar c} transition using the decay B{sup +} {yields} J/{psi}K{sup +}, and in the b {yields} dc{bar c} transition using the decay B{sup +} {yields} J/{psi}{pi}{sup +}. The decays of B{sup +} mesons are reconstructed in approximately 2.8 fb{sup -1} of data recorded by D0 detector in 2002-2007 during Run II of Fermilab Tevatron collider. Using the unbinned likelihood fit, a signal of 40,222 {+-} 242 of B{sup +} {y… more
Date: December 1, 2008
Creator: Holubyev, K.
Partner: UNT Libraries Government Documents Department
open access

The oxidation behavior of SiC sintered with Al-B-C and improved oxidation resistance via heat treatments

Description: The oxidation behavior of high strength and high toughness SiC, sintered with Al, B, and C (ABC-SiC), was examined. Kinetic data were acquired and the parabolic rate constant for oxidation was determined and compared with literature data on various SiC materials. The role of secondary phases on the oxide morphology was explored. ABC-SiC was compared to commercially available SiC, Hexoloy, and SiC sintered with 10% yttrium aluminum garnet (YAG). Two-step sintering (pre-coarsening) was employed w… more
Date: December 1, 1997
Creator: Sixta, M.
Partner: UNT Libraries Government Documents Department
open access

Developments and Applications of Electrophoresis and Small Molecule Laser Desorption Ionization Mass Spectrometry

Description: Ultra-sensitive native fluorescence detection of proteins with miniaturized one- and two-dimensional polyacrylamide gel electrophoresis was achieved with laser side-entry excitation, which provides both high excitation power and low background level. The detection limit for R-phycoerythrin protein spots in 1-D SDS-PAGE was as low as 15 fg, which corresponds to 40 thousand molecules only. The average detection limit of six standard native proteins was 5 pg per band and the dynamic range spanned … more
Date: December 1, 2007
Creator: Zhang, Hui
Partner: UNT Libraries Government Documents Department
open access

Precision Measurement of Neutrino Oscillation Parameters with KamLAND

Description: This dissertation describes a measurement of the neutrino oscillation parameters #1;{Delta}m{sup 2}{sub 21}, θ{sub 12} and constraints on θ{sub 13} based on a study of reactor antineutrinos at a baseline of ∼ 180 km with the KamLAND detector. The data presented here was collected between April 2002 and November 2009, and amounts to a total exposure of 2.64 � 0.07 � 10{sup 32} proton-years. For this exposure we expect 2140 � 74(syst) antineutrino candidates from react… more
Date: December 12, 2011
Creator: KamLAND, & O'Donnell, Thomas
Partner: UNT Libraries Government Documents Department
open access

Measurement of the neutron ({sup 3}He) spin structure functions at low Q{sup 2}: A CONNECTION BETWEEN THE BJORKEN AND GERASIMOV-DRELL-HEARN SUM RULE

Description: This dissertation presents results of experiment E94-010 performed at Jefferson Laboratory (simply known as JLab) in Hall A. The experiment aimed to measure the low Q{sup 2} evolution of the Gerasimov-Drell-Hearn (GDH) integral from Q{sup 2} = 0.1 to 0.9 GeV{sup 2}. The GDH sum rule at the real photon point provides an important test of Quantum Chromodynamics (QCD). The low Q{sup 2} evolution of the GDH integral contests various resonance models, Chiral Perturbation Theory ({chi}#31;PT) and lat… more
Date: December 1, 2002
Creator: Djawotho, Pibero
Partner: UNT Libraries Government Documents Department
open access

A measurement of the top quark mass with a matrix element method

Description: The authors present a measurement of the mass of the top quark. The event sample is selected from proton-antiproton collisions, at 1.96 TeV center-of-mass energy, observed with the CDF detector at Fermilab's Tevatron. They consider a 318 pb{sup -1} dataset collected between March 2002 and August 2004. They select events that contain one energetic lepton, large missing transverse energy, exactly four energetic jets, and at least one displaced vertex b tag. The analysis uses leading-order t{bar t… more
Date: December 1, 2006
Creator: Gibson, Adam Paul
Partner: UNT Libraries Government Documents Department
open access

Measurement of the top quark mass in the dilepton final state using the matrix element method

Description: The top quark, discovered in 1995 by the CDF and D0 experiments at the Fermilab Tevatron Collider, is the heaviest known fundamental particle. The precise knowledge of its mass yields important constraints on the mass of the yet-unobserved Higgs boson and allows to probe for physics beyond the Standard Model. The first measurement of the top quark mass in the dilepton channel with the Matrix Element method at the D0 experiment is presented. After a short description of the experimental environm… more
Date: December 1, 2008
Creator: Grohsjean, Alexander
Partner: UNT Libraries Government Documents Department
open access

Precision measurement of the top quark mass in the lepton + jets channel using a matrix element method with Quasi-Monte Carlo integration

Description: This thesis presents a measurement of the top quark mass obtained from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector. The measurement uses a matrix element integration method to calculate a t{bar t} likelihood, employing a Quasi-Monte Carlo integration, which enables us to take into account effects due to finite detector angular resolution and quark mass effects. We calculate a t{bar t} likelihood as a 2-D function of the top pole mass m{sub t} … more
Date: December 1, 2009
Creator: Lujan, Paul Joseph & /UC, Berkeley /LBL, Berkeley
Partner: UNT Libraries Government Documents Department
open access

Search for CP violation in B0s to Jpsi Phi

Description: The CDF experiment, which uses p{bar p} collisions at {radical}s = 1.9 TeV produced at the Fermilab Tevatron, is unique in its ability to observe all flavors of B hadrons and measure their properties. Among them, CP violation is of fundamental interest. In the B{sup +} and B{sup 0} systems, measurements of CP violation parameters performed essentially at B factories have borne out the predictions of CKM model. Little is known, experimentally, about CP violation in the B{sub s}{sup 0} system. Th… more
Date: December 1, 2008
Creator: Liu, Chunlei & U., /Pittsburgh
Partner: UNT Libraries Government Documents Department
open access

Precision Rosenbluth Measurement of the Proton Elastic Electromagnetic Form Factors and Their Ratio at Q^2=2.64, 3.20, and 4.10 GeV^2

Description: Due to the inconsistency in the results of the mupGEp/GMp ratio of the proton, as extracted from the Rosenbluth and recoil polarization techniques, high precision measurements of the e-p elastic scattering cross sections were made at Q{sup 2} = 2.64, 3.20, and 4.10 GeV{sup 2}. Protons were detected, in contrast to previous measurements where the scattered electrons were detected, which dramatically decreased-dependent systematic uncertainties and corrections. A single spectrometer measured the … more
Date: December 1, 2005
Creator: Qattan, Issam A.
Partner: UNT Libraries Government Documents Department
open access

Quasiparticle energy studies of bulk semiconductors, surfaces and nanotubes

Description: Effects of many-body effects on electronic excitation energies (quasiparticle band structure) of these materials are explored. GW approximation, including local field effects, for self-energy operator is used to calculate quasi-particle energies. The newly discovered carbon nanotubes are studied; structural stability and band structures are calculated. BN nanotubes are also studied, and their stability is predicted. Unexpected electronic features are predicted for both systems. Filling of carbo… more
Date: December 1, 1994
Creator: Blase, X.F.
Partner: UNT Libraries Government Documents Department
open access

Imaging gene expression in real-time using aptamers

Description: Signal transduction pathways are usually activated by external stimuli and are transient. The downstream changes such as transcription of the activated genes are also transient. Real-time detection of promoter activity is useful for understanding changes in gene expression, especially during cell differentiation and in development. A simple and reliable method for viewing gene expression in real time is not yet available. Reporter proteins such as fluorescent proteins and luciferase allow for n… more
Date: December 13, 2011
Creator: Shin, Il Chung
Partner: UNT Libraries Government Documents Department
open access

Solvation!

Description: This dissertation consists of two closely related parts: theory development and coding of correlation effects in a model potential for solvation, and study of solvent effects on chemical reactions and processes. The effective fragment potential (EFP) method has been re-parameterized, using density functional theory (DFT), more specifically, the B3LYP functional. The DFT based EFP method includes short-range correlation effects; hence it is a first step in incorporating the treatment of correlat… more
Date: December 19, 2004
Creator: Adamovic, Ivana
Partner: UNT Libraries Government Documents Department
open access

Exploration of Simple Analytical Approaches for Rapid Detection of Pathogenic Bacteria

Description: Many of the current methods for pathogenic bacterial detection require long sample-preparation and analysis time, as well as complex instrumentation. This dissertation explores simple analytical approaches (e.g., flow cytometry and diffuse reflectance spectroscopy) that may be applied towards ideal requirements of a microbial detection system, through method and instrumentation development, and by the creation and characterization of immunosensing platforms. This dissertation is organized into … more
Date: December 17, 2005
Creator: Rahman, Salma
Partner: UNT Libraries Government Documents Department
open access

A faint galaxy redshift survey behind massive clusters

Description: This thesis is concerned with the gravitational lensing effect by massive galaxy clusters. We have explored a new technique for measuring galaxy masses and for detecting high-z galaxies by their optical colors. A redshift survey has been obtained at the Keck for a magnitude limited sample of objects (I<23) behind three clusters, A1689, A2390, and A2218 within a radius of 0.5M pc. For each cluster we see both a clear trend of increasing flux and redshift towards the center. This behavior is t… more
Date: December 1, 1999
Creator: Frye, Brenda
Partner: UNT Libraries Government Documents Department
open access

Doping Experiments on Low-Dimensional Oxides and a Search for Unusual Magnetic Properties of MgAlB14

Description: Doping experiments on La{sub 2}CuO{sub 4}, Sr{sub 2}CuO{sub 3} and SrCu{sub 2}(BO{sub 3}){sub 2} were performed with the intent of synthesizing new metallic low-=dimensional cuprate oxide compounds. Magnetic susceptibility {chi}(T) measurements on a polycrystalline La{sub 2}CuO{sub 4} sample chemically oxidized at room temperature in aqueous NaClO showed superconductivity with a superconducting transition temperature T{sub c} of 42.6 K and a Meissner fraction of 26%. They were unable to electro… more
Date: December 31, 2002
Creator: Hill, Julienne Marie
Partner: UNT Libraries Government Documents Department
open access

Measurement of Cabibbo-Suppressed Tau Lepton Decays and the Determination of |Vus|

Description: This work presents simultaneous branching fraction measurements of the decay modes {tau}{sup -} {yields} K{sup -} n{pi}{sup 0}{nu}{sub {tau}} with n = 0,1,2,3 and {tau}{sup -} {yields} {pi}{sup -} n{pi}{sup 0}{nu}{sub {tau}} with n = 3,4. The analysis is based on a data sample of 427 x 10{sup 6} {tau}{sup +}{tau}{sup -} pairs recorded with the BABAR detector, which corresponds to an integrated luminosity of 464.4 fb{sup -1}. The measured values are {Beta}({tau}{sup -} {yields} K{sup -}{nu}{sub … more
Date: December 16, 2008
Creator: Schenk, Stefan
Partner: UNT Libraries Government Documents Department
open access

Effect of nuclear spin on chemical reactions and internal molecular rotation

Description: Part I of this dissertation is a study of the magnetic isotope effect, and results are presented for the separation of /sup 13/C and /sup 12/C isotopes. Two models are included in the theoretical treatment of the effect. In the first model the spin states evolve quantum mechanically, and geminate recombination is calculated by numerically integrating the collision probability times the probability the radical pair is in a singlet state. In the second model the intersystem crossing is treated vi… more
Date: December 1, 1980
Creator: Sterna, L.L.
Partner: UNT Libraries Government Documents Department
open access

Measurement of single top quark production in the tau+jets channnel using boosted decision trees at D0

Description: The top quark is the heaviest known matter particle and plays an important role in the Standard Model of particle physics. At hadron colliders, it is possible to produce single top quarks via the weak interaction. This allows a direct measurement of the CKM matrix element V{sub tb} and serves as a window to new physics. The first direct measurement of single top quark production with a tau lepton in the final state (the tau+jets channel) is presented in this thesis. The measurement uses 4.8 fb{… more
Date: December 1, 2009
Creator: Liu, Zhiyi & U., /Simon Fraser
Partner: UNT Libraries Government Documents Department
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