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B Flavour Tagging with Artificial Neural Networks for the CDF II Experiment

Description: One of the central questions arising from human curiosity has always been what matter is ultimately made of, with the idea of some kind of elementary building-block dating back to the ancient greek philosophers. Scientific activities of multiple generations have contributed to the current best knowledge about this question, the Standard Model of particle physics. According to it, the world around us is composed of a small number of stable elementary particles: Electrons and two different kinds … more
Date: January 1, 2010
Creator: Schmidt, Andreas
Partner: UNT Libraries Government Documents Department
open access

Determination of saccharides and ethanol from biomass conversion using Raman spectroscopy: Effects of pretreatment and enzyme composition

Description: This dissertation focuses on the development of facile and rapid quantitative Raman spectroscopy measurements for the determination of conversion products in producing bioethanol from corn stover. Raman spectroscopy was chosen to determine glucose, xylose and ethanol in complex hydrolysis and fermentation matrices. Chapter 1 describes the motives and main goals of this work, and includes an introduction to biomass, commonly used pretreatment methods, hydrolysis and fermentation reactions. The p… more
Date: January 1, 2010
Creator: Shih, Chien-Ju
Partner: UNT Libraries Government Documents Department
open access

Development and application of QM/MM methods to study the solvation effects and surfaces

Description: Quantum mechanical (QM) calculations have the advantage of attaining high-level accuracy, however QM calculations become computationally inefficient as the size of the system grows. Solving complex molecular problems on large systems and ensembles by using quantum mechanics still poses a challenge in terms of the computational cost. Methods that are based on classical mechanics are an inexpensive alternative, but they lack accuracy. A good trade off between accuracy and efficiency is achieved b… more
Date: January 1, 2010
Creator: Dibya, Pooja Arora
Partner: UNT Libraries Government Documents Department
open access

A genetic algorithm approach in interface and surface structure optimization

Description: The thesis is divided into two parts. In the first part a global optimization method is developed for the interface and surface structures optimization. Two prototype systems are chosen to be studied. One is Si[001] symmetric tilted grain boundaries and the other is Ag/Au induced Si(111) surface. It is found that Genetic Algorithm is very efficient in finding lowest energy structures in both cases. Not only existing structures in the experiments can be reproduced, but also many new structures c… more
Date: January 1, 2010
Creator: Zhang, Jian
Partner: UNT Libraries Government Documents Department
open access

Investigations into the origins of polyatomic ions in inductively coupled plasma-mass spectrometry

Description: An inductively coupled plasma-mass spectrometer (ICP-MS) is an elemental analytical instrument capable of determining nearly all elements in the periodic table at limits of detection in the parts per quadrillion and with a linear analytical range over 8-10 orders of magnitude. Three concentric quartz tubes make up the plasma torch. Argon gas is spiraled through the outer tube and generates the plasma powered by a looped load coil operating at 27.1 or 40.6 MHz. The argon flow of the middle chann… more
Date: January 1, 2010
Creator: McIntyre, Sally M.
Partner: UNT Libraries Government Documents Department
open access

Measurement of the inclusive forward-backward t$\bar{t}$ production asymmetry and its rapidity dependence dA<sub>fb</sub>/d(Δy)

Description: Early measurements of a large forward-background asymmetry at the CDF and D0 experiments at Fermilab have generated much recent interest, but were hampered by large uncertainties. We present here a new measurement of the parton level forward-backward asymmetry of pair-produced top quarks, using a high-statistics sample with much improved precision. We study the rapidity, y<sub>top</sub>, of the top quark production angle with respect to the incoming parton momentum in both the lab and t$\bar{t}… more
Date: January 1, 2010
Creator: Strycker, Glenn Loyd
Partner: UNT Libraries Government Documents Department
open access

Neutron scattering study of charge-ordering in R1/3Sr2/3FeO3 (R=La, Pr, Nd, Sm, and Y)

Description: The complicated physical phenomena in complex transition-metal oxides (TMO), such as high T<sub>c</sub> superconductivity, colossal magnetoresistivity, metal-insulator transitions, etc., have long been the focus of intense inquiry and debate in condensed matter science, since they are related to strong electronic correlations and cannot be explained within the 'standard model' of solid state physics. These novel functionalities of the correlated electron systems have a wide range of potential f… more
Date: January 1, 2010
Creator: Ma, Jie
Partner: UNT Libraries Government Documents Department
open access

Organic light emitting diodes (OLEDS) and OLED-based structurally integrated optical sensors

Description: General introduction to OLED basics and OLED-based structurally integrated sensors was provided in chapter 1 and chapter 2. As discussed in chapter 3, OLEDs were developed or improved using novel engineering methods for better charge injection (increased by over 1 order of magnitude) and efficiency. As the excitation sources, these OLEDs have preferred characteristics for sensor applications, including narrowed emission, emission at desired wavelength, and enhanced output for reduced EL backgro… more
Date: January 1, 2010
Creator: Cai, Yuankun
Partner: UNT Libraries Government Documents Department
open access

Search for MSSM Higgs Bosons in Tau Final States with the D0 Detector

Description: The cross-section times branching ratio of the Higgs boson decaying to τ<sup>+</sup>τ<sup>-</sup> final state in the Standard Model (SM) is too small to play any role in the SM Higgs boson searches. This, however, is different in the Minimal Supersymmetric Standard Model (MSSM), which predicts two Higgs doublets leading to five Higgs bosons: a pair of charged Higgs boson (H<sup>±</sup>); two neutral CP-even Higgs bosons (h,H) and a CP-odd Higgs boson (A). A search for the production of neutral … more
Date: January 1, 2010
Creator: Yang, Wan-Ching
Partner: UNT Libraries Government Documents Department
open access

Search for the production of the standard model z boson in association with W<sup>±</sup> boson in proton anti-p collisions at 1.96 TeV center of mass energy

Description: The search for the production of the Standard Model Z boson in association with a W boson is motivated and discussed. This is performed using 4.3 fb<sup>-1</sup> of Tevatron Run II data collected with the CDF detector in √s = 1.96 TeV proton anti-proton collisions. This is a signature-based analysis where the W boson decays semileptonically into a high-P<sub>T</sub> electron or muon plus a neutrino, and where the Z boson decays into two b quark jets (b-jets). We increase the signal-to-backgroun… more
Date: January 1, 2010
Creator: Keung, Justin Kien
Partner: UNT Libraries Government Documents Department
open access

The Search for VH → VWW standard model higgs production in the trilepton signature with 5.9fb<sup>-1</sup> of data from p$\bar{p}$ collisions at √s=1.96 GeV

Description: We present here the search for Standard Model V H → VWW → lll + E<sub>T</sub> (missing energy due to neutrinos) production, where V is a W or Z weak vector boson, which uses up to 5.9 fb<sup>-1</sup> of integrated luminosity. This analysis has recently added to the CDF high-mass Higgs group three new signal topologies characterized by a tri-lepton signature, which are chosen to isolate the V H → VWW associated production signals in the three-lepton signature. As such, we define three new region… more
Date: January 1, 2010
Creator: Nett, Jason Michael
Partner: UNT Libraries Government Documents Department
open access

Solidification, growth mechanisms, and associated properties of Al-Si and magnesium lightweight casting alloys

Description: Continually rising energy prices have inspired increased interest in weight reduction in the automotive and aerospace industries, opening the door for the widespread use and development of lightweight structural materials. Chief among these materials are cast Al-Si and magnesium-based alloys. Utilization of Al-Si alloys depends on obtaining a modified fibrous microstructure in lieu of the intrinsic flake structure, a process which is incompletely understood. The local solidification conditions,… more
Date: January 1, 2010
Creator: Hosch, Timothy
Partner: UNT Libraries Government Documents Department
open access

Spectrally narrowed leaky waveguide edge emission and transient electrluminescent dynamics of OLEDs

Description: In summary, there are two major research works presented in this dissertation. The first research project (Chapter 4) is spectrally narrowed edge emission from Organic Light Emitting Diodes. The second project (Chapter 5) is about transient electroluminescent dynamics in OLEDs. Chapter 1 is a general introduction of OLEDs. Chapter 2 is a general introduction of organic semiconductor lasers. Chapter 3 is a description of the thermal evaporation method for OLED fabrication. The detail of the firs… more
Date: January 1, 2010
Creator: Zhengqing, Gan
Partner: UNT Libraries Government Documents Department
open access

A study of muon neutrino disappearance in the MINOS detectors and the NuMI beam

Description: There is now substantial evidence that the proper description of neutrino involves two representations related by the 3 x 3 PMNS matrix characterized by either distinct mass or flavor. The parameters of this mixing matrix, three angles and a phase, as well as the mass differences between the three mass eigenstates must be determined experimentally. The Main Injector Neutrino Oscillation Search experiment is designed to study the flavor composition of a beam of muon neutrinos as it travels betwe… more
Date: January 1, 2010
Creator: Ling, Jiajie
Partner: UNT Libraries Government Documents Department
open access

Study of $WZ$ production with the DØ Detector

Description: In this Dissertation I present a detailed study of p$\bar{p}$ → WZ production using fully leptonic decays of W and Z bosons with electrons and muons in the final state. Data used for the study were collected by the DØ detector at the Fermilab p$\bar{p}$ collider with a center-of-mass energy of √s = 1.96 TeV and correspond to 4.1 fb<sup>-1</sup> of integrated luminosity. The most precise measurement of the WZ production cross section is obtained and found to be in a good agreement with the stand… more
Date: January 1, 2010
Creator: Kaadze, Ketino
Partner: UNT Libraries Government Documents Department
open access

Synthesis and structural, magnetic, thermal, and transport properties of several transition metal oxides and aresnides

Description: Oxide compounds containing the transition metal vanadium (V) have attracted a lot of attention in the field of condensed matter physics owing to their exhibition of interesting properties including metal-insulator transitons, structural transitions, ferromagnetic and an- tiferromagnetic orderings, and heavy fermion behavior. Binary vanadium oxides VnO<sub>2n-1</sub> where 2 ≤ n ≤ 9 have triclinic structures and exhibit metal-insulator and antiferromagnetic transitions.[1–6] The only exception i… more
Date: January 1, 2010
Creator: Das, Supriyo
Partner: UNT Libraries Government Documents Department
open access

Yb-based heavy fermion compounds and field tuned quantum chemistry

Description: The motivation of this dissertation was to advance the study of Yb-based heavy fermion (HF) compounds especially ones related to quantum phase transitions. One of the topics of this work was the investigation of the interaction between the Kondo and crystalline electric field (CEF) energy scales in Yb-based HF systems by means of thermoelectric power (TEP) measurements. In these systems, the Kondo interaction and CEF excitations generally give rise to large anomalies such as maxima in ρ(T) and … more
Date: January 1, 2010
Creator: Mun, Eundeok
Partner: UNT Libraries Government Documents Department
open access

The Need for a Strong Science and Technology Program in the Nuclear Weapons Complex for the 21st Century

Description: In this paper I argue for the need for a strong Science and Technology program in the Nuclear Weapons Complex as the basis for maintaining a credible deterrence capability. The current Nuclear Posture Review establishes a New Triad as the basis for the United States deterrence strategy in a changing security environment. A predictive science capability is at the core of a credible National Nuclear Weapons program in the 21st Century. In absence of nuclear testing, the certification of our curre… more
Date: January 6, 2010
Creator: Garaizar, X
Partner: UNT Libraries Government Documents Department
open access

Measurement and Modeling of Blocking Contacts for Cadmium Telluride Gamma Ray Detectors

Description: Gamma ray detectors are important in national security applications, medicine, and astronomy. Semiconductor materials with high density and atomic number, such as Cadmium Telluride (CdTe), offer a small device footprint, but their performance is limited by noise at room temperature; however, improved device design can decrease detector noise by reducing leakage current. This thesis characterizes and models two unique Schottky devices: one with an argon ion sputter etch before Schottky contact d… more
Date: January 7, 2010
Creator: Beck, P R
Partner: UNT Libraries Government Documents Department
open access

Exclusive B Decays into Final States with Two Charmed Baryons

Description: This Thesis presents measurements of the decays B{sup -} {yields} {Xi}{sub c}{sup 0}{bar {Lambda}}{sub c}{sup -}, {bar B}{sup 0} {yields} {Xi}{sub c}{sup +}{bar {Lambda}}{sub c}{sup -}, B{sup -} {yields} {Lambda}{sub c}{sup +}{bar {Lambda}}{sub c}{sup -} K{sup -}, and {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar {Lambda}}{sub c}{sup -} K{sub s}{sup 0} based on 228 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factor… more
Date: January 11, 2010
Creator: Chai, Xuedong
Partner: UNT Libraries Government Documents Department
open access

Search for the Standard Model Higgs Boson in the $WH \to \ell \nu b\bar{b}$ Channel in 1.96-TeV Proton-Antiproton Collisions

Description: We have searched for the Standard Model Higgs boson in the WH → lvbb channel in 1.96 TeV pp collisions at CDF. This search is based on the data collected by March 2009, corresponding to an integrated luminosity of 4.3 fb<sup>-1</sup>. The W H channel is one of the most promising channels for the Higgs boson search at Tevatron in the low Higgs boson mass region.
Date: February 1, 2010
Creator: Nagai, Yoshikazu
Partner: UNT Libraries Government Documents Department
open access

A Study of Muon Ionization Cooling at MICE

Description: A Neutrino Factory based on a high-energy muon storage-ring is proposed to study neutrino oscillation with high precision. An emittance reduction of muon beam by ionization cooling, which has never been demonstrated in practice, is one of the critical issues for Neutrino Factory. The international Muon Ionisation Cooling Experiment (MICE) is the first experiment to verify an effect of the ionization cooling with muons. MICE will measure a change in transverse emittance of approximately 10% with… more
Date: February 1, 2010
Creator: Sakamoto, Hideyuki
Partner: UNT Libraries Government Documents Department
open access

A top quark mass measurement using a matrix element method

Description: A measurement of the mass of the top quark is presented, using top-antitop pair (t{bar t}) candidate events for the lepton+jets decay channel. The measurement makes use of Tevatron p{bar p} collision data at centre-of-mass energy {radical}s = 1.96 TeV, collected at the CDF detector. The top quark mass is measured by employing an unbinned maximum likelihood method where the event probability density functions are calculated using signal (t{bar t}) and background (W+jets) matrix elements, as well… more
Date: February 1, 2010
Creator: Linacre, Jacob Thomas
Partner: UNT Libraries Government Documents Department
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