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My recollections as a physicist

Description: This presentation is a talk presented by the author at a Physics Symposium of the 50th anniversary of the Taiwan University, in December 1996. The author describes how he became a physicist, and then presents a brief outline of his professional career, most of which has centered at Stanford Linear Accelerator Center. He was involved in the discovery of the {tau} lepton, and in studies of CP violation through decay of the {tau}, in addition to studies of semileptonic decay of t, B, D, K, and {pi}.
Date: March 1, 1997
Creator: Tsai, Yung-su
Partner: UNT Libraries Government Documents Department

Systematics of mid-rapidity E{sub T} and multiplicity distributions in nucleus and nucleon collisions at AGS energies

Description: In the period 1986--1992, the E802 Collaboration at the BNL-AGS made systematic measurements of transverse energy (E{sub T}) emission in an electromagnetic calorimeter (PbGl) which covered the pseudorapidity interval 1.25 {le} {eta} {le} 2.50 and half the azimuth (where mid-rapidity for these energies is y{sub cm}{sup N N} {approx_equal} 1.6 - 1.7 depending the species). The other half of the azimuth was occupied by a 25 msr magnetic spectrometer with full particle identification. Runs were also taken with two different full-azimuth configurations of the PbGl, covering 1.25 {le} {eta} {le} 2.44, and also 1.3 {le} {eta} {le} 2.4. It was noticed that the shapes of the upper edges of the E{sub T} distributions, as represented for example by the p parameter in a gamma distribution fit, seemed to vary with the solid angle of the configuration. To systematically investigate this effect, the A-dependence and pseudorapidity-interval ({delta}{eta}) dependence of E{sub T} distributions in the half-azimuth electromagnetic calorimeter were measured for p+Be, p+Au, O+Cu, Si+Au and Au+Au collisions.
Date: December 31, 1998
Creator: Tannenbaum, M.J. & Collaboration, E802
Partner: UNT Libraries Government Documents Department

Ring-imaging Cerenkov studies. Final performance report

Description: This project involved collaboration in the design, construction and testing of a prototype chamber capable of detecting Cerenkov rings. The chamber incorporated several novel techniques in that it used parallel-plate pad readout and a Cesium-iodide (CsI) solid photocathode. The pad system used gas multiplication where the gas was kept at low pressure to minimize photon losses due to absorption and back-scattering and to minimize ion collection times. Low pressure also lowers the chamber response to charged particles. The chamber gas was ethane at 20 torr and the chamber was operated at room temperature. The chamber was built at the University of Pennsylvania by a University of Puerto Rico graduate student, Jorge Millan. Initial tests at Pennsylvania using a hydrogen-discharge lamp indicated a quantum efficiency of 13% at 190 nm. The chamber was then tested in the M-Test beam line at Fermilab and behind the C3 beamline dump at Brookhaven Lab. Cerenkov rings were clearly observed with each photoelectron typically exciting one pad. On average each ring had five struck pads and only 10% of the events had hits in the center due to the charged particle. These results indicate that a RICH detector using a solid CsI photocathode coupled to a low-pressure, parallel-plate pad chamber is an excellent device for particle identification in high-rate environments when there is a need to cover large areas with minimum expense.
Date: March 13, 1997
Creator: Lopez, A. M.
Partner: UNT Libraries Government Documents Department

Tau physics at CDF

Description: We discuss tau identification techniques at hadron colliders, and present the measurements and the searches performed so far. We report on the first evidence of t{anti t} production in the channel containing one hadronically decaying {tau} lepton. We also present a search for the charged Higgs boson in the tau decay channel, as well as for the leptoquark family containing tau leptons. In addition, we underline the importance of tau physics both at present and future collider experiments.
Date: August 1, 1997
Creator: Gallinaro, M.
Partner: UNT Libraries Government Documents Department

University of Virginia High Energy Physics Group. Final performance report, June 1, 1989--January 31, 1994

Description: The US Department of Energy Contracts for 1989 covered the initial year of the University of Virginia High Energy Physics Group. The first proposal was submitted in the fall of 1988 and the first allocation of funding was received in June 1989. This first contract which covered the time period June 1, 1989--January 31, 1990 was in the amount of $186,000 and covered UVa HEP group operations and equipment during that period. At that point, a regular contract year was established and two subsequent contracts were issued for February 1, 1990--January 31, 1991 and February 1, 1991--January 31, 992 with awards of $280,000 and $580,000, respectively. The funding between June, 1989 and January, 1992 covered the activities of both the UVa Theory Group (Task A) and the UVa HEP Experimental Group (Task B). Expenditures of all above funds was completed by January 31, 1994. In this time period, certain initial things were accomplished using the operating funds provided by DOE and the seed funds ($2.2 million over the period). There were three main areas of activities, the building of the University of Virginia HEP infrastructure (construction of lab space, computer facilities, electronic shop, machine shop and office space), the hiring of personnel (faculty, post docs, and students) and the physics activities of the group. Much of the physics program of the experimental group revolved around the study of production and decay of heavy flavor. A list of technical papers generated by their work is provided.
Date: December 31, 1994
Partner: UNT Libraries Government Documents Department

Measurement of M{sub w} using the transverse mass ratio of W and Z

Description: We report on the measurement of {ital W} boson mass from a direct determination of the ratio of the transverse masses of {ital W} and {ital Z} using the D{null} detector at the Fermilab Tevatron {ital p}{ital {anti p}} collider operating at {radical}s = 1.8 TeV. The analysis is a preliminary result based on a partial data sample of 13 {ital pb}{sup -1} using {ital W} {r_arrow} {ital e}{nu} and {ital Z} {r_arrow} {ital ee} decays.
Date: November 1996
Creator: Rajagopalan, S.
Partner: UNT Libraries Government Documents Department

Study of electron and neutrino interactions

Description: This is the final report for the DOE-sponsored experimental particle physics program at Virginia Tech to study the properties of the Standard Model of strong and electroweak interactions. This contract (DE-AS05-80ER10713) covers the period from August 1, 1980 to January 31, 1993. Task B of this contract, headed by Professor Alexander Abashian, is described in this final report. This program has been pursued on many fronts by the researchers-in a search for axions at SLAC, in electron-positron collisions in the AMY experiment at the TRISTAN collider in Japan, in measurements of muon decay properties in the MEGA and RHO experiments at the LAMPF accelerator, in a detailed analysis of scattering effects in the purported observation of a 17 keV neutrino at Oxford, in a search for a disoriented chiral condensate with the MiniMax experiment at Fermilab, and in an R&D program on resistive plate counters that could find use in low-cost high-quality charged particle detection at low rates.
Date: March 18, 1997
Creator: Abashian, A.
Partner: UNT Libraries Government Documents Department

Research in theoretical physics. Final report

Description: This report summarizes the research carried out under Grant DE-FG02-85ER40211. The main topics covered are: astroparticle physics at very high and ultrahigh energies; search for new physics by means of detectors of ultrahigh energy particles of extraterrestrial origin. Methods for searching in heavy quark decays for signatures of physics beyond the standard model are developed.
Date: June 1, 1998
Creator: Domokos, G. & Kovesi-Domokos, S.
Partner: UNT Libraries Government Documents Department

Search for quark-lepton compositeness using the Drell-Yan process at D-Zero

Description: We present preliminary results on the search for quark-lepton compositeness using the Drell-Yan process in p{anti p} collisions at {radical}s = 1.8 TeV. If quarks and leptons were composite with common substructure, the dielectron mass spectrum would show an excess in the high mass region relative to the Standard model. We observe no such excess. We set a 95% confidence level lower limit on the compositness scale using a contact interaction model.
Date: September 1, 1998
Partner: UNT Libraries Government Documents Department

First commissioning results from Hall A at TJNAF

Description: The commissioning and resulting capabilities of Hall A at the Thomas Jefferson National Accelerator Facility for performing coincidence experiments with a continuous wave electron beam at energies of 0.8--6.0 GeV will be described. The facility consists of a pair of high-resolution magnetic spectrometers to detect scattered particles, together with instrumentation to measure beam properties. The installation of the base equipment has been completed. Commissioning of the spectrometers, including their detector packages, is well advanced, both in single-arm mode and in coincidence mode.
Date: May 1, 1997
Creator: Collaboration, Robert Michaels for the Hall A
Partner: UNT Libraries Government Documents Department

Recent developments on the STAR detector system at RHIC

Description: The STAR detector system is designed to provide tracking, momentum analysis and particle identification for many of the mid-rapidity charged particles produced in collisions at the RHIC collider. A silicon vertex detector (SVT) provides three layers of tracking near the interaction point. This is followed by the main time projection chamber (TPC), which continues tracking out to 200 cm radial distance from the interaction region. The detector design also includes an electromagnetic calorimeter, various trigger detectors, and radial TPCs in the forward region. The entire system is enclosed in a 0.5 T solenoid magnet. A progress report is given for the various components of the STAR detector system. The authors report on the recent developments in the detector proto-typing and construction, with an emphasis on the main TPC, recent TPC cosmic ray testing and shipping to Brookhaven National Laboratory.
Date: December 1997
Creator: Argonne National Laboratory
Partner: UNT Libraries Government Documents Department

The MINOS long-baseline experiment at Fermilab

Description: The MINOS (Main Injector Neutrino Oscillation Search) long-baseline experiment will search for neutrino oscillations by measuring an intense {nu}{sub {mu}} beam at the end of a 730 km flight path. The 10,000 ton MINOS far detector will utilize magnetized steel plates interleaved with track chambers to reconstruct event topologies and to measure the energies of the muons, hadrons and electromagnetic showers produced by neutrino interactions. The experiment is designed to detect {nu}{sub {mu}} {r_arrow} {nu}{sub {tau}} and {nu}{sub {mu}} {r_arrow} {nu}{sub e} oscillations with {Delta}m{sup 2} {ge} 0.001 eV{sup 2} and sin{sup 2} (2{theta}) {ge} 0.01. Any oscillation signal observed can be verified and studied by several independent tests: a near/far rate comparison, the NC/CC event ratio, the CC and NC event energy spectra, and the identification of electrons and {tau} leptons. The neutrino beam can be operated in both wide-band and narrow-band configurations, allowing the detailed study oscillation phenomena. The experiment is scheduled to begin operation in 2001.
Date: January 2, 1997
Creator: Ayres, D.S.
Partner: UNT Libraries Government Documents Department

Exploiting the single-lepton event structure in the search for the top quark

Description: We discuss whether the event structure can be useful in searching for the top quark in the single-lepton channel at the Tevatron, where the main obstacle is a considerable background from QCD W+ multijet production. We restrict our discussion to the case of a Standard Model top quark of heavy mass, M{sub top}>100 GeV.
Date: June 1, 1993
Creator: Cobal, M.; Leone, S. & Grassman, H.
Partner: UNT Libraries Government Documents Department

Pentaquark phenomenology

Description: Heavy flavor hadron scattering and bound states give experimental information otherwise unobtainable on effective (qq){sub 6} and ({anti q}q){sub 8} interactions. All constituent quark model successes in (uds) hadron spectroscopy depend only on (qq){sub 3*} and ({anti q}q){sub 1} interactions. Reliable vertex detectors open new pentaquark search directions. Any event in with a proton emitted from a secondary vertex indicates a particle decaying weakly by proton emission and the discovery of a new particle if its mass is higher than that of known charmed baryons. There is no combinatorial background and striking decay signatures like p{phi}{pi}{sup {minus}} are no longer needed.
Date: September 1, 1997
Creator: Lipkin, H.J.
Partner: UNT Libraries Government Documents Department

Studying the spin structure of the proton using the solenoidal tracker at RHIC

Description: The primary goal of RHIC is to produce nuclear matter under extremes of temperature and density sufficient to excite the QCD vacuum, resulting in the creation of a deconfined plasma of quarks and gluons. A second goal central to the RHIC scientific program is to advance the study of the spin structure of the proton significantly beyond what has been learned from deep inelastic scattering (DIS) measurements by studying spin asymmetries in strong processes involving the partonic constituents of polarized protons. After decades of being regarded as an inessential complication to the strong interaction at high energy, spin has again become a topic of considerable experimental and theoretical interest. This is largely due to the observation from DIS that the net contribution to the proton spin from the quark constituents ({approximately} 30%) is smaller than expected relative to the momentum carried in this sector. The RHIC accelerator will provide an unprecedented opportunity to fully explore the spin structure of the proton with high precision studies focused on measuring the spin-dependent parton distributions (valence quark, sea quark, gluon) of the proton. It is designed to operate both with high luminosity (10{sup 31}--10{sup 32} cm{sup {minus}2} sec{sup {minus}1}) and high polarization ({approximately} 70%). In addition, the energy range at RHIC ({radical}s = 200--500 GeV) is sufficiently high that spin effects in polarized proton interactions should be calculable once the spin structure of the proton is sufficiently understood. The experimental results will therefore provide a rigorous test of QCD. A further focus of the RHIC spin physics program will be to search for physics beyond the standard model. The increased sensitivity afforded by using polarized protons to study parity violation in inclusive jet production at high p{sub t} makes this exploration competitive with respect to ongoing searches using unpolarized beams.
Date: May 1, 1998
Creator: Hallman, T.J. & Collaboration, STAR
Partner: UNT Libraries Government Documents Department

Searches for SUSY by CDF

Description: Data from proton-antiproton collisions at center-of-mass energy of 1.8 TeV are searched for evidence of SUSY particles. One analysis looks for the three-lepton final state from chargino-neutralino production. No events are observed. Another analysis looks for three or more jets and large missing energy as a signal of squark or gluino pair production. No significant excess of data above background is observed. The results of these searches are to extend limits on SUSY models beyond previous limits within a restricted parameter space of the models.
Date: June 26, 1995
Creator: Hauser, J.
Partner: UNT Libraries Government Documents Department

The mechanism of open-flavor strong decays

Description: In this contribution the author discusses models of two-body strong hadron decays. These models are expected to play a vital role in future attempts to identify unconventional hadrons such as glueballs and hybrids, through accurate predictions of the decay modes of conventional q{anti q} states. First, he reviews the most commonly used decay model, which is the {sup 3}P{sub 0} model developed by Micu and LeYaouanc et al., and show some of its successful predictions. Predictions of the {sup 3}P{sub 0} model for some newly discovered states are also given. Finally he discusses some attempts to identify the fundamental QCD process which underlies q{anti q} pair production in the {sup 3}P{sub 0} model. His results indicate that the dominant q{anti q} pair production process is usually pair production through the linear scalar confining interaction. Pair production from OGE in most cases is found to be a smaller amplitude, with the notable exception of {sup 3}P{sub 0} {yields} {sup 1}S{sub 0} decays such as f{sub 0}(q{anti q}) {yields} {pi}{pi}.
Date: December 1995
Creator: Barnes, T.
Partner: UNT Libraries Government Documents Department

Pion-pion correlations in Au+Au collisions at AGS energy

Description: Pion-pion correlation functions have been measured in Au+Au collisions at 10.8 GeV/c per nucleon by the E877 collaboration. The width of the peak in the correlation function for identical pions, which is related to the source size, shows a dependence on pion momenta and on the orientation of the reaction plane.
Date: December 31, 1995
Creator: Miskowiec, D. & Collaboration, The E877
Partner: UNT Libraries Government Documents Department

The search for proton decay

Description: The conservation of the quantum number called baryon number, like lepton (or family) number, is an empirical fact even though there are very good reasons to expect otherwise. Experimentalists have been searching for baryon number violating decays of the proton and neutron for decades now without success. Theorists have evolved deep understanding of the relationship between the natural forces in the development of various Grand Unified Theories (GUTs) that nearly universally predict baryon number violating proton decay, or related phenomena like n-{bar n} oscillations. With this in mind, the Proton Decay Working Group reviewed the current experimental and theoretical status of the search for baryon number violation with an eye to the advancement in the next decade.
Date: December 1994
Creator: Haines, T.; Kaneyuki, K.; McGrew, C.; Mohapatra, R.; Peterson, E. & Cline, D. B.
Partner: UNT Libraries Government Documents Department

Precision measurements in supersymmetry

Description: Supersymmetry is a promising framework in which to explore extensions of the standard model. If candidates for supersymmetric particles are found, precision measurements of their properties will then be of paramount importance. The prospects for such measurements and their implications are the subject of this thesis. If charginos are produced at the LEP II collider, they are likely to be one of the few available supersymmetric signals for many years. The author considers the possibility of determining fundamental supersymmetry parameters in such a scenario. The study is complicated by the dependence of observables on a large number of these parameters. He proposes a straightforward procedure for disentangling these dependences and demonstrate its effectiveness by presenting a number of case studies at representative points in parameter space. In addition to determining the properties of supersymmetric particles, precision measurements may also be used to establish that newly-discovered particles are, in fact, supersymmetric. Supersymmetry predicts quantitative relations among the couplings and masses of superparticles. The author discusses tests of such relations at a future e{sup +}e{sup {minus}} linear collider, using measurements that exploit the availability of polarizable beams. Stringent tests of supersymmetry from chargino production are demonstrated in two representative cases, and fermion and neutralino processes are also discussed.
Date: May 1, 1995
Creator: Feng, J.L.
Partner: UNT Libraries Government Documents Department

Search for first and second generation leptoquarks at D0

Description: A search for first and second generation pair produced scalar leptoquarks has been done with the DO detector at Fermilab`s p{bar p} machine with {radical}s = 1.8 TeV. Leptoquarks are assumed to be strictly generational; for example, a first generation leptoquark couples only to the electron, its neutrino, and the u and d quarks. 95% C.L. mass limits of 133 GeV/c{sup 2} and 120 GeV/c{sup 2} for respective 100% and 50% decay branching ratios to electron plus quark for first generation scalar leptoquarks have been published. The preliminary results of a search for second generation scalar leptoquarks in the absence of a signal are mass limits of 111 GeV/c{sup 2} and 89 GeV/c{sup 2} for 100% and 50% decay branching ratios to muon plus quark. A feature of these mass limits is that they are independent of the unknown coupling of the leptoquark to leptons and quarks. The detection for e{sup +}e{sup {minus}} and e-p machines depends on the strength of this coupling.
Date: July 1, 1995
Creator: Abachi, S.; Abbott, B. & Abolins, M.
Partner: UNT Libraries Government Documents Department

Preliminary results from IMB3 muon/electron identification tests at KEK

Description: A test has been conducted at KEK, Japan using beams of electrons and muons in a 1 kiloton water Cherenkov detector instrumented with IMB3 phototubes and electronics to evaluate IMB`s algorithms for identifying electrons and muons. This identification is important because the IMB3 detector`s results on the atmospheric neutrino anomaly depend on the proper identification of the electrons and muons produced in neutrino charged-current interactions. Preliminary results are presented.
Date: September 1, 1995
Creator: Bratton, C.B.; Breault, J. & Conner, Z.
Partner: UNT Libraries Government Documents Department

Fast Drift CRID with GEM

Description: The only available technique at the present time, to perform particle identification up to 40-50 GeV/c in a 4{pi} solenoidal geometry using the Cherenkov ring imaging method is the use of gaseous detectors tilled with either TMAE or TEA photocathodes, and a combination of the gaseous, and solid or liquid radiators. If one would consider building such a device, one may want to investigate alternative methods of building a single-electron detector. This paper investigates the feasibility of using the GEM together with a simple MWPC detector employing 33 {micro}m diameter carbon wires to obtain a second coordinate. The results are compared to the CRID single-electron detector.
Date: May 20, 1999
Creator: Va'Vra, Jaroslav
Partner: UNT Libraries Government Documents Department

Results on top quark production from D0

Description: The D{O} Collaboration reports on a search for the Standard Model top quark in p{bar p} collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron, with an integrated luminosity of approximately 50 pb{sup -1}. We have searched for t{bar t} production in the dilepton and single lepton channels with and without tagging of b quark jets. We observe 17 events with an expected background of 3.8 {plus_minus} 0.6 events. The probability for an upward, fluctuation of the background to produce the observed signal is 2 x 10{sup -6} (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measure its mass to be 199{sub -21}{sup +19}(stat.){plus_minus}22 (syst.) GeV/c{sup 2} and its production cross section to be 6.4 {plus_minus} 2.2 pb.
Date: August 1, 1995
Creator: Wimpenny, S.J.
Partner: UNT Libraries Government Documents Department