132 Matching Results

Search Results

Results: 1 - 24 next
open access

A Measurement of the Lifetime of the Lambda_b Baryon with the CDF Detector at the Tevatron Run II

Description: In March 2001 the Tevatron accelerator entered its Run II phase, providing colliding proton and anti-proton beams with an unprecedented center-of-mass energy of 1.96 TeV. The Tevatron is currently the only accelerator to produce {Lambda}{sub b} baryons, which provides a unique opportunity to measure the properties of these particles. This thesis presents a measurement of the mean lifetime of the {Lambda}{sub b} baryon in the semileptonic channel {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{s… more
Date: December 1, 2004
Creator: Unverhau, Tatjana Alberta Hanna & U., /Glasgow
Partner: UNT Libraries Government Documents Department
open access

Search for Excited or Exotic Electron Production Using the Dielectron + Photon Signature at CDF in Run II

Description: The author presents a search for excited or exotic electrons decaying to an electron and a photon with high transverse momentum. An oppositely charged electron is produced in association with the excited electron, yielding a final state dielectron + photon signature. The discovery of excited electrons would be a first indication of lepton compositeness. They use {approx} 202 pb{sup -1} of data collected in p{bar p} collisions at {radical}s = 1.96 TeV with the Collider Detector at Fermilab durin… more
Date: July 1, 2004
Creator: Gerberich, Heather Kay & U., /Duke
Partner: UNT Libraries Government Documents Department
open access

Tests of Enhanced Leading Order QCD in W Boson plus Jet Production in 1.96-TeV Proton-Antiproton Collisions

Description: The authors have studied the W + {ge} n jets process in Tevatron Run II experiment. The data used correspond to a total integrated luminosity of 72 pb{sup -1} taken from March 2002 through January 2003. The lowest order QCD predictions have been tested with a new prescription of the parton-jet matching, which allows to construct the enhanced LO phase space. According to this procedure, one gets unique results which do not depend on unphysical bias of kinematical cuts to avoid the collinear/infr… more
Date: January 1, 2004
Creator: Tsuno, Soushi
Partner: UNT Libraries Government Documents Department
open access

Measurement of the Ratio of Branching Fractions Br(Bs -> Ds- pi+)/Br(B -> D- pi+) at CDF-II

Description: The measurement of B{sub s}{sup 0} mixing is one of the flagship analyses for the Run II B physics program. The sensitivity of the measurement to the frequency of B{sub s}{sup 0} oscillations strongly depends on the number of reconstructed B{sub s}{sup 0} mesons. They present the measurement of the ratio of branching fractions Br(B{sub s}{sup 0} {yields} D{sub s}{sup -}{pi}{sup +})/Br(B{sup 0} {yields} D{sup -}{pi}{sup +}), which directly influences the number of B{sub s}{sup 0} events availabl… more
Date: March 1, 2004
Creator: Furic, Ivan Kresimir
Partner: UNT Libraries Government Documents Department
open access

A measurement of the t anti-t production cross-section in proton anti-proton collisions at s**(1/2) = 1.96-TeV with the D0 detector at the Tevatron using final states with a muon and jets

Description: A preliminary measurement of the t{bar t} production cross section at {radical}s = 1.96 TeV is presented. The {mu}-plus-jets final state is analyzed in a data sample of 94 pb{sup -1} and a total of 14 events are selected with a background expectation of 11.7 {+-} 1.9 events. The measurement yields: {sigma}{sub p{bar p} {yields} t{bar t} + X} = 2.4{sub -3.5}{sup +4.2}(stat.){sub -2.6}{sup +2.5}(syst.) {+-} 0.3(lumi.) pb. The analysis, being part of a larger effort to re-observe the top quark in … more
Date: February 1, 2004
Creator: Klute, Markus
Partner: UNT Libraries Government Documents Department
open access

The Production Cross Sections of the Weak Vector Bosons in Proton Antiproton Collisions at s**(1/2) = 1.96-TeV and a Measurement of the W Boson Decay Width

Description: The theory that describes the fundamental particle interactions is called the Standard Model, which is a gauge field theory that comprises the Glashow-Weinberg-Salam model [1, 2, 3] of the weak and electromagnetic interactions and quantum chromodynamics (QCD) [4, 5, 6], the theory of the strong interactions. The discovery of the W [7, 8] and Z [9, 10] bosons in 1983 by the UA1 and UA2 collaborations at the CERN p{bar p} collider provided a direct confirmation of the unification of the weak and … more
Date: April 1, 2004
Creator: Varganov, Alexei Valerievich
Partner: UNT Libraries Government Documents Department
open access

Experimental and Numerical Investigation of the Role of Initial Condition of the Dynamics of Rayleigh-Taylor Mixing

Description: Experiments and direct numerical simulations have been performed to examine the effects of initial conditions on the dynamics of a Rayleigh-Taylor mixing layer. Experiments were performed on a water channel facility to quantify the interfacial and velocity perturbations initially present at the two-fluid interface in a small Atwood number mixing layer. The measurements have been parameterized for implementation in numerical simulations of the experiment, and two- and three-dimensional direct nu… more
Date: August 16, 2004
Creator: Mueschke, N
Partner: UNT Libraries Government Documents Department
open access

Search for first-generation leptoquarks in the jets and missing transverse energy topology in proton-antiproton collisions at center-of-mass energy 1.96 TeV

Description: The authors performed a search for the pair production of first-generation leptoquarks using 191 pb{sup -1} of proton-antiproton collision data recorded by the CDF experiment during Run II of the Tevatron. The leptoquarks are sought via their decay into a neutrino and quark, which yields missing transverse energy and several high-E{sub T} jets. Several control regions were studied to check the background estimation from Standard Model sources, with good agreement observed in data. In the leptoq… more
Date: March 1, 2004
Creator: Tsybychev, Dmitri
Partner: UNT Libraries Government Documents Department
open access

Measurement of the top pair production cross section at CDF using neural networks

Description: In the Tevatron accelerator at Fermilab protons and antiprotons are collided at a 1.96 TeV center of mass energy. CDF and D0 are the two experiments currently operating at the Tevatron. At these energies top quark is mostly produced via strong interactions as a top anti-top pair (t{bar t}). The top quark has an extremely short lifetime and according to the Standard Model it decays with {approx} 100% probability into a b quark and a W boson. In the ''lepton+jets'' channel, the signal from top pa… more
Date: November 1, 2004
Creator: Marginean, Radu
Partner: UNT Libraries Government Documents Department
open access

Search for Gauge Mediated Supersymmetry in the gamma gamma missing ET Channel

Description: We present results on a search for Gauge Mediated Supersymmetry in the di-photon final state using Run II data collected by the D0 Experiment at the Fermilab Tevatron Collider. We discuss event selection, Standard Model backgrounds, and the lower limits on the lightest neutralino and chargino masses resulted from this analysis.
Date: December 1, 2004
Creator: Kesisoglou, Stilianos Isaak & U., /Brown
Partner: UNT Libraries Government Documents Department
open access

Mass spectrum analysis of K- pi+ from the semileptonic decay D+ --> K- pi+ mu+ nu

Description: The Higgs mechanism preserves the gauge symmetries of the Standard Model while giving masses to the W, Z bosons. Supersymmetry, which protects the Higgs boson mass scale from quantum corrections, predicts at least 5 Higgs bosons, none of which has been directly observed. This thesis presents a search for neutral Higgs bosons, produced in association with bottom quarks. The production rate is greatly enhanced at large values of the Supersymmetric parameter tan {beta}. High-energy p{bar p} collis… more
Date: March 1, 2004
Creator: Massafferri Rodrigues, Andre & /Rio de Janeiro, CBPF
Partner: UNT Libraries Government Documents Department
open access

Measurement of the W + gamma Production in Proton - Anti-proton Collisions at s**(1/2) = 1.96-TeV

Description: The authors present a measurement of the {bar p}p {yields} W{gamma} + X {yields} e{nu}{gamma} + X production cross section using data form the Collider Detector at Fermilab. The p{bar p} collisions were provided by the Tevatron Collider at a center of mass energy of 1.96 TeV. Electroweak theory includes the trilinear vector boson coupling, WW{gamma}, which contributes to the e{nu}{gamma} final state. The electron decay channel of the W provides a clean sample to study the production of diboson … more
Date: October 1, 2004
Creator: Kirby, Michael H. & U., /Duke
Partner: UNT Libraries Government Documents Department
open access

A Measurement of the production cross section of top-antitop pairs in proton-antiproton collisions at a center of mass of 1.96 TeV using secondary vertex b-tagging.

Description: A measurement of the t{bar t} pair production cross section is presented using 162 pb{sup -1} of data collected by the CDF experiment during Run II at the Tevatron. t{bar t} events in the lepton+jets channel are isolated by identifying electrons and muons, reconstructing jets and transverse missing energy, and identifying b jets with a secondary vertex tagging algorithm. The efficiency of the algorithm is measured in a control sample using a novel technique that is less dependent on the simulat… more
Date: December 1, 2004
Creator: Bachacou, Henri
Partner: UNT Libraries Government Documents Department
open access

Measurement of the t anti-t production cross-section at s**(1/2) = 1.96-TeV using lifetime tagging

Description: A measurement of the t{bar t} production cross section in the lepton+jets channels with the D0 detector at {radical}s = 1.96 TeV using the lifetime-tagging techniques is presented. The t{bar t} cross section is estimated from the combination of the e+jets and {mu}+jets channels. The obtained result {sigma}{sub t{bar t}} = 7.47{sub -1.14}{sup +1.22}(stat){sub -1.03}{sup +1.65}(syst) {+-} 0.49(lumi) pb is consistent with the Standard Model expectation.
Date: July 1, 2004
Creator: Khanov, Alexander
Partner: UNT Libraries Government Documents Department
open access

A Measurement of the Mass of the Top Quark in Lepton + Jets Events at CDF

Description: This document presents a measurement of the top quark mass using the CDF run II detector at Fermilab. Colliding beams of protons and anti-protons at Fermilab's Tevatron ({radical}s = 1.96 TeV) produce top/anti-top pairs, which decay to W{sup +}W{sup -} b{bar b}; events are selected where one W decays hadronically, and one W decays to either e or {mu} plus a neutrino. The data sample was collected between March 2002 and September 2003, and corresponds to an integrated luminosity of approximately… more
Date: December 1, 2004
Creator: Brubaker, Erik Matthews
Partner: UNT Libraries Government Documents Department
open access

Search for leptoquarks in jet topolgy with missing transverse energy using the D0 detector

Description: The D0 experiment, located at the Fermilab National Accelerator Laboratory in the US, is used to study proton-anti-proton collisions at a center of mass energy of 1.96 TeV. The experiment's data acquisition system is based on a sophisticated trigger system used to select potentially interesting events. The Level 2 Silicon Track Trigger (L2STT) is part of the trigger system that provides precise reconstruction of charged particle tracks allowing the selection of events that contain the decays of… more
Date: October 1, 2004
Creator: Zabi, Alexandre
Partner: UNT Libraries Government Documents Department
open access

BioAerosol Mass Spectrometry: Reagentless Detection of Individual Airborne Spores and Other Bioagent Particles Based on Laser Desorption/Ionization Mass Spectrometry

Description: Better devices are needed for the detection of aerosolized biological warfare agents. Advances in the ongoing development of one such device, the BioAerosol Mass Spectrometry (BAMS) system, are described here in detail. The system samples individual, micrometer-sized particles directly from the air and analyzes them in real-time without sample preparation or use of reagents. At the core of the BAMS system is a dual-polarity, single-particle mass spectrometer with a laser based desorption and io… more
Date: July 20, 2004
Creator: Steele, P T
Partner: UNT Libraries Government Documents Department
open access

Measurement of the $B \to J/\psi X$ inclusive cross-section at the collider detector at Fermilab

Description: The Collider Detector at Fermilab (CDF) is a multi-purpose detector designed to study proton-antiproton collisions at center-of-mass energies of 1.96 TeV/c{sup 2}. One of the most importatn components of CDF is the silicon tracking detector. A detailed description of the testing and construction of the CDF silicon tracker is presented. Measurements of the tracking efficiency of the completed detector are also provided. Using 36 pb{sup -1} of the J/{psi} data sample collected by CDF between Febr… more
Date: January 1, 2004
Creator: Waschke, Simon
Partner: UNT Libraries Government Documents Department
open access

Spatially indirect excitons in coupled quantum wells

Description: Microscopic quantum phenomena such as interference or phase coherence between different quantum states are rarely manifest in macroscopic systems due to a lack of significant correlation between different states. An exciton system is one candidate for observation of possible quantum collective effects. In the dilute limit, excitons in semiconductors behave as bosons and are expected to undergo Bose-Einstein condensation (BEC) at a temperature several orders of magnitude higher than for atomic B… more
Date: March 1, 2004
Creator: Lai, Chih-Wei Eddy
Partner: UNT Libraries Government Documents Department
open access

Development and Performance of Detectors for the Cryogenic Dark Matter Search Experiment with an Increased Sensitivity Based on a Maximum Likelihood Analysis of Beta Contamination

Description: The Cryogenic Dark Matter Search (CDMS) uses cryogenically-cooled detectors made of germanium and silicon in an attempt to detect dark matter in the form of Weakly-Interacting Massive Particles (WIMPs). The expected interaction rate of these particles is on the order of 1/kg/day, far below the 200/kg/day expected rate of background interactions after passive shielding and an active cosmic ray muon veto. Our detectors are instrumented to make a simultaneous measurement of both the ionization ene… more
Date: January 1, 2004
Creator: Driscoll, Donald D. & U., /Case Western Reserve
Partner: UNT Libraries Government Documents Department
open access

Toward Femtosecond X-ray Spectroscopy at the Advanced Light Source

Description: The realization of tunable, ultrashort pulse x-ray sources promises to open new venues of science and to shed new light on long-standing problems in condensed matter physics and chemistry. Fundamentally new information can now be accessed. Used in a pump-probe spectroscopy, ultrashort x-ray pulses provide a means to monitor atomic rearrangement and changes in electronic structure in condensed-matter and chemical systems on the physically-limiting time-scales of atomic motion. This opens the way… more
Date: April 16, 2004
Creator: Chong, Henry Herng Wei
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

Oxidation Behavior and Chlorination Treatment to Improve Oxidation Resistance of Nb-Mo-Si-B Alloys

Description: This thesis is written in an alternate format. The thesis is composed of a general introduction, two original manuscripts, and a general conclusion. References cited within each chapter are given at the end of each chapter. The general introduction starts with the driving force behind this research, and gives an overview of previous work on boron doped molybdenum silicides, Nb/Nb{sub 5}Si{sub 3} composites, boron modified niobium silicides and molybdenum niobium silicides. Chapter 2 focuses on … more
Date: December 19, 2004
Creator: Behrani, Vikas
Partner: UNT Libraries Government Documents Department
open access

New Palladium-Catalyzed Approaches to Heterocycles and Carbocycles

Description: The tert-butylimines of o-(1-alkynyl)benzaldehydes and analogous pyridinecarbaldehydes have been cyclized under very mild reaction conditions in the presence of I{sub 2}, ICl, PhSeCl, PhSCl and p-O{sub 2}NC{sub 6}H{sub 4}SCl to give the corresponding halogen-, selenium- and sulfur-containing disubstituted isoquinolines and naphthyridines, respectively. Monosubstituted isoquinolines and naphthyridines have been synthesized by the metal-catalyzed ring closure of these same iminoalkynes. This meth… more
Date: December 19, 2004
Creator: Huang, Qinhua
Partner: UNT Libraries Government Documents Department
Back to Top of Screen