77 Matching Results

Search Results

Results: 1 - 24 next
open access

Production, Characterization, and Acceleration of Optical Microbunches

Description: Optical microbunches with a spacing of 800 nm have been produced for laser acceleration research. The microbunches are produced using a inverse Free-Electron-Laser (IFEL) followed by a dispersive chicane. The microbunched electron beam is characterized by coherent optical transition radiation (COTR) with good agreement to the analytic theory for bunch formation. In a second experiment the bunches are accelerated in a second stage to achieve for the first time direct net acceleration of electron… more
Date: June 20, 2008
Creator: Sears, Christopher M.S. & /SLAC, /Stanford U.
Partner: UNT Libraries Government Documents Department
open access

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

Description: This thesis presents the results of an analysis of {nu}{sub {mu}} disappearance with the MINOS experiment, which studies the neutrino beam produced by the NuMI facility at Fermi National Accelerator Laboratory. The rates and energy spectra of charged current {nu}{sub {mu}} interactions are measured in two similar detectors, located at distances of 1 km and 735 km along the NuMI beamline. The Near Detector provides accurate measurements of the initial beam composition and energy, while the Far D… more
Date: June 1, 2008
Creator: Marshall, John Stuart & U., /Cambridge
Partner: UNT Libraries Government Documents Department
open access

Search for new physics coupling to the z boson

Description: We present the results of two searches for new particles that couple Z bosons in p{bar p} collisions at {radical}s = 1.96 TeV using the Collider Detector at Fermilab (CDF). In the first, we search for a long-lived parent of the Z boson using a data sample with a luminosity of 163 pb{sup -1}. Finding no significant excess above background, we set a limit on a fourth generation model as a function of mass and lifetime. In the second, we search for a particle that decays to a Z boson in conjunctio… more
Date: June 1, 2007
Creator: Scott, Adam Liddle
Partner: UNT Libraries Government Documents Department
open access

Measurement of the Hadronic Mass Spectrum in B to Xulnu Decaysand Determination of the b-Quark Mass at the BaBar Experiment

Description: I present preliminary results of the measurement of the hadronic mass spectrum and its first three spectral moments in inclusive charmless semileptonic B-meson decays. The truncated hadronic mass moments are used for the first determination of the b-quark mass and the nonperturbative parameters {mu}{sub {pi}}{sup 2} and {rho}{sub D}{sup 3} in this B-meson decay channel. The study is based on 383 x 10{sup 6} B{bar B} decays collected with the BABAR experiment at the PEP-II e{sup +}e{sup -} stora… more
Date: June 26, 2008
Creator: Tackmann, Kerstin & /UC, Berkeley /SLAC
Partner: UNT Libraries Government Documents Department
open access

Study of B_s Mixing at the D-Zero Detector at Fermilab Using the Semi-leptonic Decay B_s -> D_s mu nu X

Description: B{sub s}{sup 0} mixing studies provide a precision test of Charge-Parity violation in the Standard Model. A measurement of {Delta}m{sub s} constrains elements of the CKM quark rotation matrix [1], providing a probe of Standard Model Charge-Parity violation. This thesis describes a study of B{sub s}{sup 0} mixing in the semileptonic decay B{sub s}{sup 0} {yields} D{sub s}{sup -} {mu}{sup +}{nu}X, where D{sub s}{sup -} {yields} {phi}{pi}{sup -}, using data collected at the D-Zero detector at Ferm… more
Date: June 1, 2008
Creator: Anzelc, Meghan
Partner: UNT Libraries Government Documents Department
open access

A Study of The Standard Model Higgs, WW and ZZ Production in Dilepton Plus Missing Transverse Energy Final State at CDF Run II

Description: We report on a search for Standard Model (SM) production of Higgs to WW* in the two charged lepton (e, {mu}) and two neutrino final state in p{bar p} collisions at a center of mass energy {radical}s = 1.96 TeV. The data were collected with the CDF II detector at the Fermilab Tevatron and correspond to an integrated luminosity of 1.9fb{sup -1}. The Matrix Element method is developed to calculate the event probability and to construct a likelihood ratio discriminator. There are 522 candidates obs… more
Date: June 1, 2008
Creator: Hsu, Shih-Chieh & /UC, San Diego
Partner: UNT Libraries Government Documents Department
open access

Study of the heavy flavour fractions in z+jets events from proton-antiproton collisions at energy = 1.96 TeV with the CDF II detector at the Tevatron collider

Description: The Standard Model of field and particles is the theory that provides the best description of the known phenomenology of the particle physics up to now. Data collected in the last years, mainly by the experiments at the big particle accelerators (SPS, LEP, TEVATRON, HERA, SLAC), allowed to test the agreement between measurements and theoretical calculations with a precision of 10{sup -3} {divided_by} 10{sup -4}. The Standard Model is a Quantum Field Theory based on the gauge symmetry group SU(3… more
Date: June 1, 2008
Creator: Mastrandrea, Paolo & U., /Siena
Partner: UNT Libraries Government Documents Department
open access

First Measurement of sigma(gg -> ttbar)/sigma(ppbar -> ttbar)

Description: The work presented here is the first measurement of the fraction of top quark pair production through gluon-gluon fusion. We use an integrated luminosity of 0.96 {+-} 0.06 fb{sup -1} of p{bar p} collisions at {radical}s of 1.96 TeV collected by the CDF II detector. We select t{bar t} candidates by identifying a high-p{sub T} lepton candidate, a large missing E{sub T} as evidence for a neutrino candidate and at least four high E{sub T} jets, one of which has to be identified as originating from … more
Date: June 1, 2008
Creator: Pashapour Alamdari, Shabnaz & U., /Toronto
Partner: UNT Libraries Government Documents Department
open access

A measurement of the top pair production cross-section in the dilepton channel using lepton plus track selection

Description: Using 1.1 fb{sup -1} of data collected by the Collider Detector at Fermilab (CDF) from Run II of the Fermilab Tevatron, they measure the t{bar t} production cross section in events with two leptons, significant missing transverse energy, and {ge} 2 jets. As the Run II dataset grows, more stringent tests of Standard Model predictions for the top quark sector are becoming possible. The dilepton channel, where both top quarks decay t {yields} Wb {yields} {ell}{nu}b, is of particular interest due t… more
Date: June 1, 2007
Creator: Mills, Corrinne Elaine
Partner: UNT Libraries Government Documents Department
open access

Low Temperature Constrained Sintering of Cerium Gadolinium OxideFilms for Solid Oxide Fuel Cell Applications

Description: Cerium gadolinium oxide (CGO) has been identified as an acceptable solid oxide fuel cell (SOFC) electrolyte at temperatures (500-700 C) where cheap, rigid, stainless steel interconnect substrates can be used. Unfortunately, both the high sintering temperature of pure CGO, >1200 C, and the fact that constraint during sintering often results in cracked, low density ceramic films, have complicated development of metal supported CGO SOFCs. The aim of this work was to find new sintering aids for … more
Date: June 30, 2007
Creator: Nicholas, Jason.D.
Partner: UNT Libraries Government Documents Department
open access

Search for Doubly-charged Higgs Boson Production in the Decay H++ H-- ---> mu+ mu+ mu- mu- with 1.1 fb**(-1) at D0 Detector

Description: This work presents a search for the pair production of doubly-charged Higgs bosons in the process p{bar p} {yields} H{sup ++}H{sup --} {yields} {mu}{sup +}{mu}{sup +}{mu}{sup -}{mu}{sup -} using the data corresponding to an integrated luminosity of about 1.1 fb{sup -1}. This is the complete dataset of RunIIa taken from April 19, 2002 to February 22, 2006 by the D0 experiment at the Fermilab Tevatron Collider. In the absence of significant excess above standard model background, 95% confidence l… more
Date: June 1, 2007
Creator: Kim, Tae Jeong & U., /Korea
Partner: UNT Libraries Government Documents Department
open access

M dwarfs in the Local Milky Way: The Field Low-Mass Stellar Luminosity and Mass Functions

Description: Modern sky surveys, such as the Sloan Digital Sky Survey (SDSS) and the Two-Micron All Sky Survey, have revolutionized how Astronomy is done. With millions of photometric and spectroscopic observations, global observational properties can be studied with unprecedented statistical significance. Low-mass stars dominate the local Milky Way, with tens of millions observed by SDSS within a few kpc. Thus, they make ideal tracers of the Galactic potential, and the thin and thick disks. In this thesis … more
Date: June 1, 2006
Creator: Bochanski, John J., Jr. & /Washington U., Seattle, Astron. Dept.
Partner: UNT Libraries Government Documents Department
open access

The Study of WGamma production at D0: Anomalous Coupling Limits and the Radiation Amplitude Zero

Description: W{gamma} production is analyzed in the electron and muon decay channels with approximately 1 fb{sup -1} of data from p{bar p} collisions that were produced at a center-of-mass energy of {radical}s = 1.96 TeV and that were collected by the D0 detector at the Fermilab Tevatron collider. The inclusive p{bar p} {yields} {ell}{nu}{gamma} cross section is measured in both channels and is found to be consistent with the Standard Model expectation of 2.08 {+-} 0.05{sub PDF} pb for events with a photon … more
Date: June 1, 2007
Creator: Pawloski, Gregory J. & U., /Rice
Partner: UNT Libraries Government Documents Department
open access

Measurement of the W Boson Mass with the D0 Run II Detector using the Electron P(T) Spectrum

Description: This thesis is a description of the measurement of the W boson mass using the D0 Run II detector with 770 pb{sup -1} of p{bar p} collision data. These collisions were produced by the Tevatron at {radical}s = 1.96 TeV between 2002 and 2006. We use a sample of W {yields} e{nu} and Z {yields} ee decays to determine the W boson mass with the transverse momentum distribution of the electron and the transverse mass distribution of the boson. We measure M{sub W} = XXXXX {+-} 37 (stat.) {+-} 26 (sys. t… more
Date: June 1, 2008
Creator: Andeen, Timothy R., Jr.
Partner: UNT Libraries Government Documents Department
open access

Studies in High Current Density Ion Sources for Heavy Ion FusionApplications

Description: This dissertation develops diverse research on small (diameter {approx} few mm), high current density (J {approx} several tens of mA/cm{sup 2}) heavy ion sources. The research has been developed in the context of a programmatic interest within the Heavy Ion Fusion (HIF) Program to explore alternative architectures in the beam injection systems that use the merging of small, bright beams. An ion gun was designed and built for these experiments. Results of average current density yield (<J>… more
Date: June 1, 2002
Creator: Chacon-Golcher, E.
Partner: UNT Libraries Government Documents Department
open access

MRI of Heterogeneous Hydrogenation Reactions Using Parahydrogen Polarization

Description: The power of magnetic resonance imaging (MRI) is its ability to image the internal structure of optically opaque samples and provide detailed maps of a variety of important parameters, such as density, diffusion, velocity and temperature. However, one of the fundamental limitations of this technique is its inherent low sensitivity. For example, the low signal to noise ratio (SNR) is particularly problematic for imaging gases in porous materials due to the low density of the gas and the large vo… more
Date: June 25, 2008
Creator: Burt, Scott R & Burt, Scott R.
Partner: UNT Libraries Government Documents Department
open access

Microfabrication of an Implantable silicone Microelectrode array for an epiretinal prosthesis

Description: Millions of people suffering from diseases such as retinitis pigmentosa and macular degeneration are legally blind due to the loss of photoreceptor function. Fortunately a large percentage of the neural cells connected to the photoreceptors remain viable, and electrical stimulation of these cells has been shown to result in visual perception. These findings have generated worldwide efforts to develop a retinal prosthesis device, with the hope of restoring vision. Advances in microfabrication, i… more
Date: June 10, 2003
Creator: Maghribi, M
Partner: UNT Libraries Government Documents Department
open access

IMPROVING THE PHYSICS IMPACT OF NEXT-GENERATION 76GE NEUTRINOLESS DOUBLE-BETA DECAY EXPERIMENTS

Description: Summary and Conclusions - It was shown that segmentation and pulse-shape discrimination can improve the discovery sensitivity of a next-gen 0vBB-decay experiment by 90%. - However, when practical aspects are considered (such as instrumenting each segment with front-end electronics), the discovery sensitivity is decreased by 19%. - This has extremely important consequences to proposed next-gen experiments since the two active collaborations have strongly advocated the use of segmented detectors … more
Date: June 2009
Creator: Hossbach, Todd W.
Partner: UNT Libraries Government Documents Department
open access

Microphysical Properties of Single and Mixed-Phase Arctic Clouds Derived from AERI Observations

Description: A novel new approach to retrieve cloud microphysical properties from mixed-phase clouds is presented. This algorithm retrieves cloud optical depth, ice fraction, and the effective size of the water and ice particles from ground-based, high-resolution infrared radiance observations. The theoretical basis is that the absorption coefficient of ice is stronger than that of liquid water from 10-13 mm, whereas liquid water is more absorbing than ice from 16-25 um. However, due to strong absorption in… more
Date: June 1, 2003
Creator: Turner, David D.
Partner: UNT Libraries Government Documents Department
open access

Search for Resonances in the Photoproduction of Proton-Antiproton Pairs

Description: Results are reported on the reaction {gamma}p {yields} p{bar p}p with beam energy in the range 4.8-5.5 GeV. The data were collected at the Thomas Jefferson National Accelerator Facility in CLAS experiment E01-017(G6C). The focus of this study is an understanding of the mechanisms of photoproduction of proton-antiproton pairs, and to search for intermediate resonances, both narrow and broad, which decay to p{bar p}. The total measured cross section in the photon energy range 4.8-5.5 GeV is {sigm… more
Date: June 30, 2006
Creator: Stokes, Burnham
Partner: UNT Libraries Government Documents Department
open access

Study of B-Meson Decays to Final States with a Single Charm Baryon

Description: A study of B-meson decays to final states with a single charm baryon is presented based on data recorded by the BABAR detector at the Stanford Linear Accelerator Center. Although the B meson is the lightest bottom-flavored meson, it is heavy enough to decay to a baryon made of three quarks and an antibaryon made of three antiquarks. By studying the baryonic weak decays of the B meson, we can investigate baryon production mechanisms in heavy meson decays. In particular, we measure the rates of t… more
Date: June 2, 2009
Creator: Majewski, Stephanie A.
Partner: UNT Libraries Government Documents Department
open access

Search for the Standard Model Higgs boson in the missing energy topology with D0

Description: A search for the Standard Model Higgs boson in the missing energy and acoplanar b-jet topology is reported, using an integrated luminosity of 0.93 fb{sup -1} recorded by the D0 detector at the Fermilab Tevatron p{bar p} Collider. The analysis includes signal contributions from p{bar p} {yields} ZH {yields} {nu}{bar {nu}}b{bar b}, as well as from WH production in which the charged lepton from the W boson decay is undetected. Neural networks are used to separate signal from background. In the abs… more
Date: June 1, 2009
Creator: Christoudias, Theodoros
Partner: UNT Libraries Government Documents Department
open access

A Limit on the Branching Ratio of the Flavor-Changing Top Quark Decay t-->Zc

Description: We have used the Collider Detector at Fermilab (CDF-II) to set upper limits on the branching ratio of the flavor-changing neutral-current (FCNC) top quark decay t {yields} Zc using a technique employing ratios of W and Z production, measured in 1.52 fb{sup -1} of p{bar p} data. The analysis uses a comparison of two decay chains, p{bar p} {yields} t{bar t} {yields} WbWb {yields} {ell}{nu}bjjb and p{bar p} {yields} t{bar t} ZcWb {yields} {ell}{sup +}{ell}{sup -} cjjb, to cancel systematic uncerta… more
Date: June 1, 2009
Creator: Paramonov, Alexander Andreevich
Partner: UNT Libraries Government Documents Department
open access

Measurement of the electroweak top quark production cross section and the CKM matrix element Vtb with the D0 experiment

Description: At particle accelerators the Standard Model has been tested and will be tested further to a great precision. The data analyzed in this thesis have been collected at the world's highest energetic-collider, the Tevatron, located at the Fermi National Accelerator Laboratory (FNAL) in the vicinity of Chicago, IL, USA. There, protons and antiprotons are collided at a center-of-mass energy of {radical}s = 1.96 TeV. The discovery of the top quark was one of the remarkable results not only for the CDF … more
Date: June 1, 2009
Creator: Kirsch, Matthias
Partner: UNT Libraries Government Documents Department
Back to Top of Screen