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Identifying the origin of new gauge bosons at the SSC and LHC

Description: The ability of an SCD-like detector to identify the origin of a new neutral gauge boson Z{sub 2}, once it has been discovered at the SSC and/or LHC, is examined. 9 refs., 3 figs.
Date: August 1, 1991
Creator: Hewett, J.L. (Argonne National Lab., IL (United States)) & Rizzo, T.G. (Argonne National Lab., IL (United States) Ames Lab., IA (United States))
Partner: UNT Libraries Government Documents Department

Decays of the tau lepton

Description: Previous measurements of the branching fractions of the tau lepton result in a discrepancy between the inclusive branching fraction and the sum of the exclusive branching fractions to final states containing one charged particle. The sum of the exclusive branching fractions is significantly smaller than the inclusive branching fraction. In this analysis, the branching fractions for all the major decay modes are measured simultaneously with the sum of the branching fractions constrained to be one. The branching fractions are measured using an unbiased sample of tau decays, with little background, selected from 207 pb/sup -1/ of data accumulated with the Mark II detector at the PEP e/sup +/e/sup -/ storage ring. The sample is selected using the decay products of one member of the ..gamma../sup +/..gamma../sup -/ pair produced in e/sup +/e/sup -/ annihilation to identify the event and then including the opposite member of the pair in the sample. The sample is divided into subgroups according to charged and neutral particle multiplicity, and charged particle identification. The branching fractions are simultaneously measured using an unfold technique and a maximum likelihood fit. The results of this analysis indicate that the discrepancy found in previous experiments is possibly due to two sources. First, the leptonic branching fractions measured in this analysis are about one standard deviation higher than the world average. The measured leptonic branching fractions correspond to a tau lifetime of (3.0 +- 0.2) x 10/sup -13/ s. Secondly, the total branching fraction to one charged hadron plus at least one neutral particle is measured to be (7 +- 3)% higher than the branching fraction expected from a combination of previous measurements and theoretical predictions. It is shown that decay modes involving the eta are not expected to contribute more than 3% to this excess.
Date: February 1, 1986
Creator: Burchat, P.R.
Partner: UNT Libraries Government Documents Department

Detector simulation needs for detector designers

Description: Computer simulation of the components of SSC detectors and of the complete detectors will be very important for the designs of the detectors. The ratio of events from interesting physics to events from background processes is very low, so detailed understanding of detector response to the backgrounds is needed. Any large detector for the SSC will be very complex and expensive and every effort must be made to design detectors which will have excellent performance and will not have to undergo major rebuilding. Some areas in which computer simulation is particularly needed are pattern recognition in tracking detectors and development of shower simulation code which can be trusted as an aid in the design and optimization of calorimeters, including their electron identification performance. Existing codes require too much computer time to be practical and need to be compared with test beam data at energies of several hundred GeV. Computer simulation of the processing of the data, including electronics response to the signals from the detector components, processing of the data by microprocessors on the detector, the trigger, and data acquisition will be required. In this report we discuss the detector simulation needs for detector designers.
Date: November 1, 1987
Creator: Hanson, G.G.
Partner: UNT Libraries Government Documents Department

Development of CRID (Cerenkov Ring Imaging Detector) single electron wire detector

Description: We describe the R and D effort to define the design parameters, method of construction and experimental results from the single electron wire detectors. These detectors will be used for particle identification using the Cerenkov Ring Imaging techniques in the SLD experiment at SLAC. We present measurements of pulse heights for several gases as a function of gas gain, charge division performance on a single electron signal using both 7 /mu/m and 33 /mu/m diameter carbon wires, photon feedback in TMAE laden gas, average pulse shape, and its comparison with the predicted shape and cross-talk. In addition, we present results of wire aging tests, and other tests associated with construction of this unusual type of wire chamber. 12 refs., 9 figs.
Date: February 1, 1989
Creator: Aston, D.; Bean, A.; Bienz, T.; Bird, F.; Caldwell, D.; Cavalli-Sforza, M. et al.
Partner: UNT Libraries Government Documents Department

Elementary Particle Interactions. Progress Report, October 1, 1994--September 30, 1995

Description: This year has been a busy and demanding one with completion of a long SLD run, much progress on light quark states from E-687 resulting in strong evidence for two new states, observation in E-144 of non-linear Compton scattering (multiphoton absorption by electrons) up to N-4 and initial evidence for e{sup +}e{sup {minus}} pair production in Compton process. The authors have also made considerable progress toward preparation for a n-{bar n} oscillation experiment and have carried out experimental studies of quartz fiber calorimetry for SLD polarimeter and forward calorimeter for CMS and LHC including a thorough set of gamma ray and neutron radiation damage studies on quartz fiber. Two graduate students received their Ph.D.s this year, Kathy Danyo Blackett on data from Fermilab E-687 and Sharon White on SLD radiative Bhabha scattering.
Date: October 1995
Creator: Bugg, W. M.; Condo, G T.; Handler, T.; Hart, E. L.; Read, K.; Siopsis, G. et al.
Partner: UNT Libraries Government Documents Department

(Relativistic heavy ion research)

Description: At Brookhaven National Laboratory, participation in the E802 Experiment, which is the first major heavy-ion experiment at the BNL-AGS, was the main focus of the group during the past four years. The emphases of the E802 experiment were on (a) accurate particle identification and measurements of spectra over a wide kinematical domain (5{degree} < {theta}{sub LAB} < 55{degree}, p < 20 GeV/c); and (b) measurements of small-angle two-particle correlations, with event characterization tools: multiplicity array, forward and large-angle calorimeters. This experiment and other heavy ion collision experiments are discussed in this report.
Date: January 1, 1990
Partner: UNT Libraries Government Documents Department

Experiments using the TASS and HISS spectrometers at the Bevalac. Progress report, July 1, 1980-March 31, 1981

Description: The LSU intermediate energy physics group has participated in the construction and calibration of the two-armed-spectrometer-system (TASS) at the Lawrence Berkeley Laboratory. The data collection phase of the first experiment on the spectrometer is complete, and some results are reported. (GHT)
Date: January 1, 1981
Creator: Kirk, P.N.
Partner: UNT Libraries Government Documents Department

New limits on generation-1 leptoquarks

Description: With the turn-on of HERA there is currently considerable interest in the properties of first-generation leptoquarks. In this paper we present new results of a search for these particles at CDF. Our findings are based on an analysis of 4.1 pb[sup [minus]1] of data collected at [radical]s = 1.8 TeV during the 1988--89 Tevatron run. The leptoquarks are assumed to decay rapidly to first-generation leptons and quarks. We search for an excess of events containing two high energy electrons and two jets and find no events in our signal region. Events outside the signal region are consistent with Z[sup 0] +dijet production. Based on this, and assuming BR(LQ[sub 1][yields] e + q) = 100 %, we exclude first-generation leptoquarks with masses M(LQ[sub 1]) < 113 GeV at the 95% CL. At BR(LQ[sub 1][yields] e + q) = 50 %, we exclude M(LQ[sub 1]) < 82 GeV.
Date: November 1, 1992
Creator: Moulding, S.M. (Brandeis Univ., Waltham, MA (United States))
Partner: UNT Libraries Government Documents Department

Status and future prospects for supersymmetry at the Tevatron

Description: We investigate the potential for discovery of super-symmetry during the next Tevatron Collider run in the light of new results fro LEP and CDF.
Date: January 1, 1990
Creator: Amos, N. (Fermi National Accelerator Lab., Batavia, IL (United States)); De, K. (Michigan Univ., Ann Arbor, MI (United States)); White, A. (Florida Univ., Gainesville, FL (United States)) & Yamin, P. (Brookhaven National Lab., Upton, NY (United States))
Partner: UNT Libraries Government Documents Department

AGS silicon gold collisions measured in the E-810 TPC (Time Projection Chamber)

Description: The tracking detector of AGS Experiment 810 is a three-piece Time Projection Chamber (TPC) intended to measure all charged tracks in the forward hemisphere of the nucleon-nucleon center of mass system, i.e. forward of an angle of about 20 degrees in the lab. Each module of the TPC contains twelve rows of short anode wires which give 3-D space points on each track, but no dE/dx information useable for particle identification. The TPC was operated in a beam of silicon ions at the end of June 1989 and this talk reports the results of analysis of the data taken with a thin gold target in that run. We have gathered a similar amount of data from thin copper and silicon targets, the analysis of which is in a less advanced state. The results of our investigation of the neutral strange particle decays appear in a separate contribution by Al Saulys. This paper presents the current state of the analysis of the charged tracks from the silicon gold collisions. 1 ref., 15 figs.
Date: March 26, 1990
Creator: Bonner, B. E.; Buchanan, J. A.; Chiou, C. N.; Clement, J. M.; Corcoran, M. D.; Kruk, J. W. et al.
Partner: UNT Libraries Government Documents Department

CDF measurements of the W mass and search for the top

Description: The derivation of the W mass value of 79.91 [plus minus] 0.39 GeV/c[sup 2] is discussed. The present limit at 91 GeV/c[sup 2] (95% C.L.) on the mass of the top quark is also presented. In the next two years of data collection, we expect to collect significantly more luminosity than in the past. We discuss prospects for the discovery of the top quark and improvements of the current measurements.
Date: October 1, 1992
Creator: Leone, S. (Istituto Nazionale di Fisica Nucleare, Pisa (Italy))
Partner: UNT Libraries Government Documents Department

e[sup [plus]]e[sup [minus]] linear colliders and new particle searches

Description: We discuss future e[sup +]e[sup [minus]] linear colliders and new particle searches that can be done with them. In the discussion of new particle searches we examine the following topics: searches for gauge boson structure, searches for a strongly interacting Higgs sector, top quark studies, Higgs searches, supersymmetric particle searches and measurements of soft supersymmetry breaking parameters.
Date: January 1, 1993
Creator: Barklow, T.L.
Partner: UNT Libraries Government Documents Department

Identification of W pairs at the SSC

Description: The background for W pairs at the SSC is analysed. A procedure is developed to obtain a signal/background ratio of order 1/1 for one leptonic and one hadronic decay. 20 references.
Date: January 1, 1984
Creator: Fernandez, E.; Grannis, P.D.; Linn, S.L.; Hauptman, J.M.; Paige, F.E. & Selove, W.
Partner: UNT Libraries Government Documents Department

Calorimetry in ZEUS: Lessons for the future

Description: The storage ring facility HERA, under construction at the DESY Laboratory, will collide 30 GeV e/sup /minus// with 820 GeV protons when the machine is first turned on in 1990. Four interaction regions being provided. Subsequently either e/sup /minus// or e beams can be used and a facility for producing longitudinal polarization of the electrons at the interaction points will be provided. Both the center-of-mass energy ( s = 314 GeV) and the momentum transfer (Q/sub max/S /approximately/ 10V GeVS) are substantially higher than in any deep inelastic scattering studies to date. The HERA program will be the natural extension of both the neutrino and the muon scattering experiments done at CERN and Fermilab. With the design luminosity of 1.5 10T cm/sup /minus/2/ sec/sup /minus/1/ experiments with 200 pb/sup /minus/1/ of integrated luminosity will be possible. HERA will be the first electron-quark collider. The energy is substantially higher than LEP, and the events will be cleaner than those resulting from p/bar p/ collisions. It provides the third leg that will support the physics stool of the 1990s. In neutral current events, the z exchange graph is comparable in strength to the photon exchange and the charged current events will provide unique insights into the W coupling. There will be substantial rates of heavy quark production. Two detectors are under construction: H1 uses a large solenoid with a liquid argon calorimeter inside the coil, ZEUS uses a smaller magnet with uranium-scintillator calorimeters outside of the coil. 4 refs., 11 figs.
Date: January 1, 1988
Creator: Derrick, M.
Partner: UNT Libraries Government Documents Department

Bose-Einstein correlations of pions in e/sup +/e/sup minus/ annihilation at 29 GeV center-of-mass energy

Description: Measurements of two- and three-particle correlations between like-sign pions produced in e/sup +/e/sup minus/ annihilation at 29 GeV center-of-mass energy are presented. The analysis is based on data taken during the period 1982--1986 using the TPC/2..gamma.. detector at PEP. Two-particle correlations are studied as a function of Q, the momentum difference as measured in the rest frame of the pion pair, and as a function of q/sub 0/, the energy difference as measured in the lab frame. The Bose-Einstein enhancement is observed when Q is small even when the energy difference, q/sub 0/, is substantial. This observation provides evidence that the Bose-Einstein correlations are best described by a model that correctly accounts for the relativistic motion of the particle sources. Three-pion correlations are measured both by using a standard three-pion correlation function, and also by using a correlation function for which the correlations between the pairs of pions within the triplet have been subtracted. The observation of three-pion correlations after pair correlations have been subtracted supports the interpretation that the observed correlations are due to Bose-Einstein interference. 56 refs.
Date: January 13, 1989
Creator: Avery, R.E.
Partner: UNT Libraries Government Documents Department

Cerenkov ring imaging detector development at SLAC

Description: The imaging of Cerenkov light on to photosensitive detectors promises to be a powerful technique for identifying particles in colliding beam spectrometers. Toward this end two and three dimensional imaging photon detectors are being developed at SLAC. The present techniques involve photon conversion using easily ionized exotic chemicals like tetrakisdimethyl-amino-ethylene (TMAE) in a drift and amplifying gas mixture of methane and isobutane. Single photoelectrons from Cerenkov light are currently being drifted 20 cm and a new device under study will be used to study drifting up to 80 cm along a magnetic field. A short description of a large device currently being designed for the SLD spectrometer at the Stanford Linear Collider will be given.
Date: June 1, 1984
Creator: Williams, S.H.
Partner: UNT Libraries Government Documents Department

Cerenkov ring imaging detector development: Progress report

Description: We present recent progress on the construction and testing of the first drift boxes and single electron detectors as they come from the production line. These detectors will be used for particle identification using the Ring Imaging technique in the SLD experiment at SLAC. Various experimental results are presented, including single electron pulse height measurements as a function of gas gain, detector gating capability, uniformity of response across the wire plane, charge division performance of a single electron signal, average pulse shape and its comparison with predicted shape, and cross-talk. 14 refs., 11 figs.
Date: October 1, 1988
Creator: Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dunwoodie, W.; Hallewell, G. et al.
Partner: UNT Libraries Government Documents Department

Colliding beam detectors for the SSC (Superconducting Super Collider)

Description: After a brief discussion of the requirements for the detectors to be used at the SSC, the components of a typical detector are discussed individually, and how they may fit into a full detector is indicated. The requirements indicated include the ability to detect and measure the directions and energies of quarks, gluons, leptons and photons; ability to handle appropriately high energies and high luminosities; and affordability, buildability, and operability. The components discussed include tracking detectors (such as drift chambers, calorimeters, lepton identification and energy measurement systems, triggering, and a 4..pi.. detector. (LEW)
Date: October 1, 1986
Creator: Trilling, G.H.
Partner: UNT Libraries Government Documents Department

Drift chamber tracking with neural networks

Description: We discuss drift chamber tracking with a commercial log VLSI neural network chip. Voltages proportional to the drift times in a 4-layer drift chamber were presented to the Intel ETANN chip. The network was trained to provide the intercept and slope of straight tracks traversing the chamber. The outputs were recorded and later compared off line to conventional track fits. Two types of network architectures were studied. Applications of neural network tracking to high energy physics detector triggers is discussed.
Date: October 1, 1992
Creator: Lindsey, C.S.; Denby, B. & Haggerty, H.
Partner: UNT Libraries Government Documents Department

Double semi-leptonic charm decay in helios-I 450 GeV/c p-Be data

Description: Data taken in 1989 by HELIOS-I (NA34) at the CERN SPS (450 GeV/c proton beam on Be target) have been examined for e[sup [plus minus]] [mu][sup [minus plus]] or [mu][sup [plus minus]] [mu][sup [minus plus]] pairs with associated missing energy. Such pairs arise from semi-leptonic decay of both members of a c[bar c] pair. The e[mu] and [mu][mu] samples are consistent with expectations from charm decay, allowing a quantitative limit to be placed on other physics.
Date: January 1, 1992
Creator: Pierre, A. (Montreal Univ., PQ (Canada). Dept. of Physics) & Pomianowski, P.A. (Pittsburgh Univ., PA (United States). Dept. of Physics)
Partner: UNT Libraries Government Documents Department

The signature of sequential charged leptons

Description: I am honored to be invited to give a talk on this occasion to celebrate Martin Perl's 65th birthday. John Jaros, the organizer of this occasion, wanted me to recollect several things, especially: what motivated me to write my 1971 Physical Review paper on the heavy lepton entitled Decay Correlations of Heavy Lepton in e[sup minus] + e[sup +] = [ell][sup -] + [ell]+;'' why did I think of muon-electron coincidence; and what were the contributions of Thacker and Sakurai. In this paper I answer his requests and add something else later.
Date: December 1, 1992
Creator: Tsai, Y.S.
Partner: UNT Libraries Government Documents Department

A transition radiation detector which features accurate tracking and dE/dx particle identification

Description: We describe the results of a test run involving a Transition Radiation Detector that can both distinguish electrons from pions with momenta greater than 0.7 GeV/c and simultaneously track particles passing through the detector. The particle identification is accomplished through a combination of the detection of Transition Radiation from the electron and the differences in electron and pion energy loss (dE/dx) in the detector. The dE/dx particle separation is most efficient below 2 GeV/c while particle ID utilizing Transition Radiation is effective above 1.5 GeV/c. Combined, the electron-pion separation is better than 5 [times] l0[sup 2]. The single-wire, track-position resolution for the TRD is [approximately]230[mu]m.
Date: January 1, 1991
Creator: O'Brien, E.; Lissauer, D.; McCorkle, S.; Polychronakos, V.; Takai, H. (Brookhaven National Lab., Upton, NY (United States)); Chi, C.Y. et al.
Partner: UNT Libraries Government Documents Department