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Search for Charged Massive Long-Lived Particles Using the D0 Detector

Description: A search for charged massive stable particles has been performed with the D0 detector using 1.1 fb{sup -1} of data. The speed of the particle has been calculated based on the time-of-flight and position information in the muon system. The present research is limited to direct pair-production of the charged massive long-lived particles. We do not consider CMSPs that result from the cascade decays of heavier particles. In this analysis, the exact values of the model parameters of the entire supersymmetric particle mass spectrum, relevant for cascade decays, are not important. We found no evidence of the signal. 95% CL cross-section upper limits have been set on the pair-productions of the stable scaler tau lepton, the gaugino-like charginos, and the higgsino-like charginos. The upper cross section limits vary from 0.31 pb to 0.04 pb, for stau masses in the range between 60 GeV and 300 GeV. We use the nominal value of the theoretical cross section to set limits on the mass of the pair produced charginos. We exclude the pair-produced stable gaugino-like charginos with mass below 206 GeV, and higgsino-like charginos below 171 GeV, respectively. Although the present sensitivity is insufficient to test the model of the pair produced stable staus, we do set cross section limits which can be applied to the pair production of any charged massive stable particle candidates with similar kinematics. These are the most restrictive limits to the present on the cross sections for CMSPs and the first published from the Tevatron Collider Run II. The manuscript has been published by Physical Review Letters in April 2009 and is available at arXiv as.
Date: May 1, 2009
Creator: Xie, Yunhe & U., /Brown
Partner: UNT Libraries Government Documents Department

Top quark pair production cross section in the lepton+jets channel using b-tagging at D0

Description: The top quark pair production cross section measurement in the lepton+jets channel with b-tagging algorithm is described. About 900 pb{sup -1} data collected by the D0 detector at the Fermilab Tevatron are used for this analysis. In this thesis, event selection, background estimation, and cross section calculation are discussed in detail. In addition, calibration of the Luminosity Monitor readout electronics and a new b-tagging algorithm, the SLTNN tagger, are also discussed in this thesis.
Date: May 1, 2008
Creator: Yoo, H.D. & U., /Brown
Partner: UNT Libraries Government Documents Department

Top Quark Produced Through the Electroweak Force: Discovery Using the Matrix Element Analysis and Search for Heavy Gauge Bosons Using Boosted Decision Trees

Description: The top quark produced through the electroweak channel provides a direct measurement of the V{sub tb} element in the CKM matrix which can be viewed as a transition rate of a top quark to a bottom quark. This production channel of top quark is also sensitive to different theories beyond the Standard Model such as heavy charged gauged bosons termed W{prime}. This thesis measures the cross section of the electroweak produced top quark using a technique based on using the matrix elements of the processes under consideration. The technique is applied to 2.3 fb{sup -1} of data from the D0 detector. From a comparison of the matrix element discriminants between data and the signal and background model using Bayesian statistics, we measure the cross section of the top quark produced through the electroweak mechanism {sigma}(p{bar p} {yields} tb + X, tqb + X) = 4.30{sub -1.20}{sup +0.98} pb. The measured result corresponds to a 4.9{sigma} Gaussian-equivalent significance. By combining this analysis with other analyses based on the Bayesian Neural Network (BNN) and Boosted Decision Tree (BDT) method, the measured cross section is 3.94 {+-} 0.88 pb with a significance of 5.0{sigma}, resulting in the discovery of electroweak produced top quarks. Using this measured cross section and constraining |V{sub tb}| < 1, the 95% confidence level (C.L.) lower limit is |V{sub tb}| > 0.78. Additionally, a search is made for the production of W{prime} using the same samples from the electroweak produced top quark. An analysis based on the BDT method is used to separate the signal from expected backgrounds. No significant excess is found and 95% C.L. upper limits on the production cross section are set for W{prime} with masses within 600-950 GeV. For four general models of W{prime} boson production using decay channel W{prime} {yields} t{bar b}, the lower ...
Date: February 1, 2010
Creator: Pangilinan, Monica & U., /Brown
Partner: UNT Libraries Government Documents Department

Searches for long lived particles at the Tevatron

Description: Several searches have been performed for long lived particles using data collected by the CDF and D0 detectors at the Fermilab Tevatron collider. These include searches for charged massive stable particles, stopped gluinos, neutral long-lived particles decaying to muons, and magnetic monopoles. These proceedings [1] review recent experimental results from Run II analyses.
Date: April 1, 2008
Creator: Bose, Tulika & U., /Brown
Partner: UNT Libraries Government Documents Department

Searches for non-standard-model Higgs bosons at the Tevatron

Description: Search for non-Standard-Model Higgs bosons is one of the major goals of the ongoing Fermilab Tevatron run. Large data sets accumulated by the CDF and D{O} experiments break new grounds in sensitivity. We review recent Tevatron results on searches for Higgs bosons in Minimal Supersymmetric Model in the multi b-jet and {tau}{tau} final states, as well as a search for fermiophobic Higgs in the multiphoton final state.
Date: May 1, 2007
Creator: Landsberg, Greg L. & U., /Brown
Partner: UNT Libraries Government Documents Department

Collider searches for extra dimensions

Description: Searches for extra spatial dimensions remain among the most popular new directions in our quest for physics beyond the Standard Model. High-energy collider experiments of the current decade should be able to find an ultimate answer to the question of their existence in a variety of models. Until the start of the LHC in a few years, the Tevatron will remain the key player in this quest. In this paper, we review the most recent results from the Tevatron on searches for large, TeV{sup -1}-size, and Randall-Sundrum extra spatial dimensions, which have reached a new level of sensitivity and currently probe the parameter space beyond the existing constraints. While no evidence for the existence of extra dimensions has been found so far, an exciting discovery might be just steps away.
Date: December 1, 2004
Creator: Landsberg, Greg & U., /Brown
Partner: UNT Libraries Government Documents Department

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

Ultrafast Time-Resolved Electron Diffraction with Megavolt Electron Beams

Description: An rf photocathode electron gun is used as an electron source for ultrafast time-resolved pump-probe electron diffraction. We observed single-shot diffraction patterns from a 160 nm Al foil using the 5.4 MeV electron beam from the Gun Test Facility at the Stanford Linear Accelerator. Excellent agreement with simulations suggests that single-shot diffraction experiments with a time resolution approaching 100 fs are possible.
Date: October 24, 2006
Creator: Hastings, J.B.; /SLAC; Rudakov, F.M.; U., /Brown; Dowell, D.H.; Schmerge, J.F. et al.
Partner: UNT Libraries Government Documents Department

Radiation damage to scintillator in the D0 luminosity monitor

Description: We report the result of evaluating radiation damage to Bicron BC408 plastic scintillator used in the D0 Luminosity Monitor during Run IIa. The Luminosity Monitor provides pseudo-rapidity coverage over the range 2.7 < |{eta}| < 4.4, with the radiation dose in Run IIa estimated to be 0.5 MRad for the region closest to the beams. We find the light yield is degraded by 10-15% due to radiation damage by comparing new and old scintillator in four observables: (1) visual inspection, (2) optical transmittance, (3) response to the radioactive source of {sup 90}Sr and (4) light yield for cosmic rays.
Date: December 1, 2006
Creator: Casey, Brendan; DeVaughan, Kayle; U., /Brown U. /Nebraska; Enari, Yuji; Partridge, Richard; U., /Brown et al.
Partner: UNT Libraries Government Documents Department

Development of a Non-Magnetic Inertial Sensor for Vibration Stabilization in a Linear Collider

Description: One of the options for controlling vibration of the final focus magnets in a linear collider is to use active feedback based on accelerometers. While commercial geophysics sensors have noise performance that substantially exceeds the requirements for a linear collider, they are physically large, and cannot operate in the strong magnetic field of the detector. Conventional nonmagnetic sensors have excessive noise for this application. We report on the development of a non-magnetic inertial sensor, and on a novel commercial sensor both of which have demonstrated the required noise levels for this application.
Date: September 1, 2006
Creator: Frisch, Josef; Decker, Valentin; Doyle, Eric; Hendrickson, Linda; Himel, Thomas; Markiewicz, Thomas et al.
Partner: UNT Libraries Government Documents Department

A Muon Exposure in the Tohoku High Resolution Bubble Chamber

Description: The authors would like to propose an experiment to investigate muon induced interactions in the Tohoku freon bubble chamber, a high resolution 4{pi} detector. The Tohoku bubble chamber is located in Lab F on the neutrino beam line. The NT test beam line, which passes 4.5 meters east of the bubble chamber, has carried a muon beam to Lab F in the past. it appears possible to bend this beam to the west sufficiently to send muons of approximately 200 GeV to the present position of the Tohoku chamber. A bubble chamber experiment will have better systematics than a comparable muons cattering experiment using counters, but will have lower statistics. With the chamber, direct observation of neutral strange particle and charm particle production will make possible a unique clean study of the virtual photon interactions involved.
Date: January 1, 1986
Creator: Chen, A.; Shapire, A.; Widgoff, M.; U., /Brown; Childress, S.; Murphy, T. et al.
Partner: UNT Libraries Government Documents Department

The D0 experiment's integrated luminosity for Tevatron Run IIa

Description: An essential ingredient in all cross section measurements is the luminosity used to normalize the data sample. In this note, we present the final assessment of the integrated luminosity recorded by the D0 experiment during Tevatron Run IIa. The luminosity measurement is derived from hit rates from the products of inelastic proton-antiproton collisions registered in two arrays of scintillation counters called the luminosity monitor (LM) detectors. Measured LM rates are converted to absolute luminosity using a normalization procedure that is based on previously measured inelastic cross sections and the geometric acceptance and efficiency of the LM detectors for registering inelastic events. During Run IIa, the LM detector performance was improved by a sequence of upgrades to the electronic readout system and other factors summarized in this note. The effects of these changes on the reported luminosity were tracked carefully during the run. Due to the changes, we partition the run into periods for which different conversions from measured LM rates to absolute luminosity apply. The primary upgrade to the readout system late in Run IIa facilitated a reevaluation of the overall normalization of the luminosity measurement for the full data sample. In this note, we first review the luminosity measurement technique employed by D0. We then summarize the changes to the LM system during Run IIa and the corresponding normalization adjustments. The effect of the adjustments is to increase D0's assessment of its recorded integrated luminosity compared to what was initially reported during Run IIa. The overall increase is 13.4% for data collected between April 20, 2002 (the beginning of Run IIa data used for physics analysis) and February 22, 2006 (the end of Run IIa).
Date: April 1, 2007
Creator: Andeen, T.; Casey, B.C.K.; DeVaughan, K.; Enari, Y.; Gallas, E.; Krop, D. et al.
Partner: UNT Libraries Government Documents Department

Determination of the effective inelastic p anti-p cross-section for the D0 Run II luminosity measurement

Description: The authors determine the effective inelastic p{bar p} cross-section into the D0 Luminosity Monitor for all run periods prior to September 2004. This number is used to relate the measured inelastic collision rate to the delivered luminosity. The key ingredients are the inelastic p{bar p} cross-section, the Luminosity Monitor efficiency, and the modeling of kinematic distributions for various inelastic processes used to determine the detector acceptance. The resulting value is {sigma}{sub p{bar p},eff} = 46 {+-} 3 mb.
Date: November 1, 2004
Creator: Edwards, T.; U., /Manchester; Yacoob, S.; Andeen, T.; U., /Northwestern; Begel, M. et al.
Partner: UNT Libraries Government Documents Department

Test of Proportional Wire Chambers in Hybrid Systems

Description: This is an agreement between the National Accelerator Laboratory and Professor I. Pless of MIT representing the experimenters to provide selected instrumentation for the beam to the 30-inch bubble chamber, and to use the hybrid chamber for an experiment. This document contains an enumeration of the major items needed for the proper execution of Experiment No. 154 as expressed in the proposal for the experiment, subsequent correspondence, and the draft agreement. This agreement covers phases I and II of the experiment. In Phase I the experimenters will design, construct and bring into operation a complete upstream proportional chamber system. This system will tag incident beam particles as to type by correlating the Cerenkov signals furnished by NAL with the proper incoming particle. In addition, the system will measure the position of the incident particle which passed through the momentum slit. The system will contain three proportional wire chambers (3 planes each) which will provide data suitable for defining the incident beam both as to position and angle. The experimenters will furnish the computer, magnetic tape units, programs, and all necessary readout and interface hardware. When the system is installed, debugged, documented and completely functional, it will be turned over to NAL to be operated as a general facility. Phase II of the experiment consists of an exposure of about 20,000 30-inch bubble chamber pictures ({approx}6 beam tracks per picture) correlated with data from a set of proportional wire chambers downstream from the chamber. The experimenters expect to demonstrate the utility of the proportional chamber spectrometer by attempting to analyze every event. They will do this before requesting a major exposure.
Date: June 23, 1971
Creator: Fong, D.G.; Shapiro, A.M.; Widgott, M.; U., /Brown; Ascoli, G.; Eisenstein, B. et al.
Partner: UNT Libraries Government Documents Department

Hadron spectra from high energy proton proton interactions

Description: It is proposed to measure the hadron spectra resulting from high energy proton-proton collisions using a single arm focusing spectrometer. These measurements will provide elastic and inelastic P-P cross sections for incident beam energies up to 200 GeV/c and for momentum transfers |t| from 0.01 up to about 10 to 15 (BeV/c){sup 2}. In addition, they will obtain yields of pions and kaons produced in the interactions.
Date: June 1, 1970
Creator: Diebold, R.; /Argonne; Guerriero, L.; U., /Bari; Lanou, R.; U., /Brown et al.
Partner: UNT Libraries Government Documents Department

Multiple Correlations and High Tranverse Momentum Jets in 147-GeV/c pi- p Interactions

Description: We examine multiparticle correlations in a {pi}{sup -}p experiment at 147 GeV/c performed by the Proportional Hybrid System Consortium. The major aim of this paper is to demonstrate the existence of clusters in our data. We use different statistical algorithms to assemble into clusters the particles in each event which are associated by virtue of small relative angles. We find that these clusters are stable against different choices of metric and/or algorithm, and reproduce the effects previously observed in the data corresponding to clusters. Some of these clusters have properties similar to high p{sub T} jets. A detailed study of these jet-like clusters is described, and comparisons with some counter experiments are discussed.
Date: March 1, 1981
Creator: Brick, D.; Shapiro, A.M.; Widgoff, M.; U., /Brown; Alyea, E.D., Jr.; U., /Indiana et al.
Partner: UNT Libraries Government Documents Department

A low-threshold analysis of CDMS shallow-site data

Description: Data taken during the final shallow-site run of the first tower of the Cryogenic Dark Matter Search (CDMS II) detectors have been reanalyzed with improved sensitivity to small energy depositions. Four {approx}224 g germanium and two {approx}105 g silicon detectors were operated at the Stanford Underground Facility (SUF) between December 2001 and June 2002, yielding 118 live days of raw exposure. Three of the germanium and both silicon detectors were analyzed with a new low-threshold technique, making it possible to lower the germanium and silicon analysis thresholds down to the actual trigger thresholds of {approx}1 keV and {approx}2 keV, respectively. Limits on the spin-independent cross section for weakly interacting massive particles (WIMPs) to elastically scatter from nuclei based on these data exclude interesting parameter space for WIMPs with masses below 9 GeV/c{sup 2}. Under standard halo assumptions, these data partially exclude parameter space favored by interpretations of the DAMA/LIBRA and CoGeNT experiments data as WIMP signals, and exclude new parameter space for WIMP masses between 3 GeV/c{sup 2} and 4 GeV/c{sup 2}.
Date: October 1, 2010
Creator: Akerib, D.S.; U., /Case Western Reserve; Attisha, M.J.; U., /Brown; Baudis, L.; U., /Zurich-Irchel et al.
Partner: UNT Libraries Government Documents Department

Deep Underground Science and Engineering Lab: S1 Dark Matter Working Group

Description: In this report we have described the broad and compelling range of astrophysical and cosmological evidence that defines the dark matter problem, and the WIMP hypothesis, which offers a solution rooted in applying fundamental physics to the dynamics of the early universe. The WIMP hypothesis is being vigorously pursued, with a steady march of sensitivity improvements coming both from astrophysical searches and laboratory efforts. The connections between these approaches are profound and will reveal new information from physics at the smallest scales to the origin and workings of the entire universe. Direct searches for WIMP dark matter require sensitive detectors that have immunity to electromagnetic backgrounds, and are located in deep underground laboratories to reduce the flux from fast cosmic-ray-muon-induced neutrons which is a common background to all detection methods. With US leadership in dark matter searches and detector R&D, a new national laboratory will lay the foundation of technical support and facilities for the next generation of scientists and experiments in this field, and act as magnet for international cooperation and continued US leadership. The requirements of depth, space and technical support for the laboratory are fairly generic, regardless of the approach. Current experiments and upgraded versions that run within the next few years will probe cross sections on the 10{sup -45}-10{sup -44} cm{sup 2} scale, where depths of 3000-4000 m.w.e. are sufficient to suppress the neutron background. On the longer term, greater depths on the 5000-6000 level are desirable as cross sections down to 10{sup -46} cm{sup 2} are probed, and of course, if WIMPs are discovered then building up a statistical sample free of neutron backgrounds will be essential to extracting model parameters and providing a robust solution to the dark matter problem. While most of the detector technologies are of comparable physical scale, i.e., the various ...
Date: June 9, 2006
Creator: Akerib, Daniel S.; Aprile, E.; U., /Case Western Reserve U. /Columbia; Baltz, E.A.; /KIPAC, Menlo Park; Dragowsky, M.R. et al.
Partner: UNT Libraries Government Documents Department

The SuperCDMS Experiment

Description: Modest improvements in the level and/or discrimination of backgrounds are needed to keep backgrounds negligible during the three phases of SuperCDMS. By developing production designs that require only modest testing, detector production rates may be improved sufficiently to allow an exposure of 500 ton d within a reasonable time and budget. Overall, the improvement estimates described above are conservative. Previous development efforts have shown that some areas prove easier and provide larger factors while others prove more difficult. The conservative estimates together with the broad approach reduce the risk and give us confidence that we will succeed, providing the surest way to probe to WIMP-nucleon cross sections of 10{sup -46} cm{sup 2}.
Date: February 1, 2005
Creator: Schnee, Richard W.; Akerib, D. S.; Attisha, M. J.; Bailey, C. N.; Baudis, L.; Bauer, Daniel A. et al.
Partner: UNT Libraries Government Documents Department