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Studies of nuclear reaction at very low energies

Description: The deuteron radiative capture reactions on {sup 2}H, {sup 6}Li and {sup 10}B have been measured between center of mass energies of 20 and 140 keV. Of note is the observation that the gamma ray-to-charged particle branching ratio for the DD reaction appears independent of energy down to a center of mass energy of 20 keV, consistent with some and contrary to other theoretical models. We have investigated the ratio of the reactions D(d,p)T and D(d,n){sup 3}He down to c.m. energies of 3 keV and the ratio of the reactions 6Li(d,p){sup 7}Li and {sup 6}LI(d,{alpha}){sup 4}He down to a c.m. energy of 19 keV. The DD reaction ratio is independent of energy while the (d,p) branch of the D-{sup 6}Li evinces a significant enhancement at the lowest measured energies. We have continued our investigation of charged particle production from deuterium-metal systems at a modest level of activity. Noteworthy in this investigation is the observation of 3 MeV protons from deuteron beam loaded Ti and LiD targets subjected to extreme thermal disequilibria. Significant facility improvements were realized during the most recent contract period. Specifically the downstream magnetic analysis system proposed to eliminate beam induced contaminants has been installed and thoroughly tested. This improvement should allow the D(a,{gamma}){sup 6}Li reaction to be measured in the coming contract period. A scattering chamber required for the measurement of the {sup 7}Li({sup 3}He,p){sup 9}Be reaction has been designed, fabricated and installed on the accelerator. A CAMAC based charged particle identification system has been assembled also for use in our proposed measurement of the {sup 7}Li({sup 3}He, p){sup 9}Be.
Date: January 15, 1992
Creator: Cecil, F.E.
Partner: UNT Libraries Government Documents Department

STAR: Visualization and infrastructure software. Progress report, 1996

Description: One of the two primary experiments approved for day-one operation at the Relativistic Heavy Ion Collider (RHIC) is the Solenoidal Tracker at RHIC (STAR). This report summarizes the work carried out by personnel from the University of Texas at Austin on the STAR experiment at RHIC during the calendar year 1995--1996. Topics covered are: (1) STAR visualization; (2) DFM, the Data File Manager; (3) LEV: Logging of Environment and Version Information; (4) TBR: the Table Browser; (5) STIC (Star Idl Compiler); (6) CDS (Code Style checker); (7) TOP (Table Operators); (8) Publications 1995--1996; (i) Abstracts of conference or symposium proceedings and reports 1995--1996; and (10) Personnel.
Date: November 1, 1996
Creator: Moore, C. F.
Partner: UNT Libraries Government Documents Department

The production of {pi}{sup {+-}}, K{sup {+-}}, p, k{sup 0} and {Lambda}{sup 0} in hadronic Z{sup 0} decays

Description: The authors have measured production fractions and spectra for {pi}{sup {+-}}, K{sup {+-}} and p, and production spectra for K{sup 0} and {Lambda}{sup 0} in both hadronic Z{sup 0} decays and a Z{sup 0} {yields} light quark (uds) subset at SLD. The SLD Cherenkov Ring Imaging Detector was used to identify charged hadrons. The CCD vertex detector was used to select the enriched uds sample. For the global sample, the results are consistent with previous experiments. The authors observe a clear flavor dependence in production spectra, but only a small effect in hadron fractions and {xi} = ln(1/x{sub p}) peak positions.
Date: August 1, 1995
Creator: Baird, K.
Partner: UNT Libraries Government Documents Department

Search for new phenomena in CDF-I: Z{prime}, W{prime} and leptoquarks

Description: We present the latest results of CDF searches for Z{prime}, W{prime} and leptoquarks. Using about 70pb{sup -1} data from 1992-95 CDF runs, we have searched for Z{prime} {yields} l{sup +}l{sup -}, W{prime} {yields} WZ and pairs of second generation scalar leptoquark, S{sub 2}. We find no evidence for these new particles, and set new mass limits at 95% CL. We exclude M{sub Z{prime}} < 650 GeV/c{sup 2}, 205 < M{prime}{sub W} < 400 GeV/c{sup 2}, and M{sub S2} < 180 GeV/c{sup 2} for {beta} = 1 and M{sub S2} < 141 GeV/c{sup 2} for {beta} = 0.5. Two interesting strange events are also shown.
Date: July 1, 1995
Creator: Park, S.
Partner: UNT Libraries Government Documents Department

Strong interaction physics with pions at LAMPF: Report of the study group on future opportunities at LAMPF

Description: The LAMPF accelerator, with its high-intensity teams of pions and array of high-resolution spectrometers, provides opportunities for investigations of nuclear structure as well as of strong-interaction hadron dynamics. During operation of LAMPF as a national users facility, Nuclear Physics has undergone an evolution in the way it pictures nuclei: from a system of nucleons interacting through potentials to a system of mutually coupled nucleons, {Delta}(1232)`s, and mesons. While nuclear physics is in the midst of yet another shift of paradigm, with quarks and gluons playing a central role, the traditional picture still has great predictive power, and LAMPF has new opportunities to contribute to solving problems of current interest. At the same time, LAMPF is poised to make important contributions to the evolving area of nonperturbative QCD, where we will be learning how to connect phenomena at large momentum transfer to those at lower momentum scales. where the physically observable hadrons are the natural degrees of freedom. Within the traditional area, exploration of nuclei having extreme ratios of neutron/proton number is of growing interest in a variety of contexts, including astrophysics. Pion double charge exchange (the ({pi}{sup {plus_minus}}, {pi}{sup {plus_minus}}) processes) can produce proton-rich nuclei such as {sup 9}C, {sup 10}C, and {sup 11}N as well as neutron-rich nuclei such as {sup 10}He, {sup 11}Li, {sup 14}Be, and {sup 17}B. With spectrometers available for analyzing the outgoing pion spectra, one can study interesting and controversial modes of motion (soft-dipole modes) and obtain angular distributions that explore the spatial extent of neutron halos.
Date: July 1, 1995
Creator: Johnson, M.B. & Matthews, J.L.
Partner: UNT Libraries Government Documents Department

First results with the Microball and Gammasphere

Description: The Microball, an improved 4{pi} multi-detector array, was used recently in conjunction with Gammasphere in three experiments. Highlights of the first results are presented here. The Microball consists of 95 CsI(T{ell}) scintillation detectors with individual Si photodiode readout, arranged in 9 rings. In these first experiments the Microball performed as designed, but the results in new physics exceeded the authors` expectations. They can say with certainty that by its powerful channel selection the Microball enhanced the performance of Gammasphere by one full coincidence fold. This was possible for all exit channels involving charged particle emission, with increasing performance benefit as one progressed to lighter reaction systems. They summarize the essential characteristics of the Microball and give some performance benchmarks. A detailed description of the Microball is given.
Date: December 31, 1994
Creator: Sarantites, D.G.; Hua, P.F. & LaFosse, D.
Partner: UNT Libraries Government Documents Department

Vertex detectors

Description: The purpose of a vertex detector is to measure position and angles of charged particle tracks to sufficient precision so as to be able to separate tracks originating from decay vertices from those produced at the interaction vertex. Such measurements are interesting because they permit the detection of weakly decaying particles with lifetimes down to 10{sup {minus}13} s, among them the {tau} lepton and charm and beauty hadrons. These two lectures are intended to introduce the reader to the different techniques for the detection of secondary vertices that have been developed over the past decades. The first lecture includes a brief introduction to the methods used to detect secondary vertices and to estimate particle lifetimes. It describes the traditional technologies, based on photographic recording in emulsions and on film of bubble chambers, and introduces fast electronic registration of signals derived from scintillating fibers, drift chambers and gaseous micro-strip chambers. The second lecture is devoted to solid state detectors. It begins with a brief introduction into semiconductor devices, and then describes the application of large arrays of strip and pixel diodes for charged particle tracking. These lectures can only serve as an introduction the topic of vertex detectors. Time and space do not allow for an in-depth coverage of many of the interesting aspects of vertex detector design and operation.
Date: July 1, 1992
Creator: Lueth, V.
Partner: UNT Libraries Government Documents Department

Search for exotic particles at CDF

Description: CDF has searched for 2nd generation leptoquarks, new gauge bosons W{prime} and Z{prime}, axigluons, excited quarks, color octet technirhos and E{sub 6} diquarks. We place the most stringent limits on direct production of these exotic particles.
Date: February 1, 1995
Creator: Harris, R.M.
Partner: UNT Libraries Government Documents Department

The inclusive jet cross section at {radical}s = 630 GeV at D0

Description: The authors present a preliminary measurement of the cross section for central inclusive jet production at {radical}s = 630 GeV using {approximately} 400 nb{sup {minus}1} of data collected during the December 1995 Fermilab collider run at D0. These results are compared to NLO QCD predictions.
Date: September 1, 1996
Creator: Krane, J.
Partner: UNT Libraries Government Documents Department

The BNL rare kaon decay program

Description: The rare kaon decay program at Brookhaven National Laboratory is reviewed. Results from the last round of experiments are briefly discussed. The three experiments currently collecting data are described. Prospects for future experiments are discussed.
Date: December 31, 1996
Creator: Littenberg, L.
Partner: UNT Libraries Government Documents Department

Study of electron and neutrino interactions. Final report

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

Prospects for HERMES-spin structure studies at HERA

Description: HERMES (HERA Measurement of Spin), is a second generation experiment to study the spin structure of the nucleon by using polarized internal gas targets in the HERA 35-GeV electron storage ring. Scattered electrons and coincident hadrons will be detected in an open geometry spectrometer which will include particle identification. Measurements are planned for each of the inclusive structure functions, g{sub 1},(x), g{sub 2}(x), b{sub 1}(x) and A(x), as well as the study of semi-inclusive pion and kaon asymmetries. Targets of hydrogen, deuterium and {sup 3}He will be studied. The accuracy of data for the inclusive structure functions will equal or exceed that of current experiments. The semi-inclusive asymmetries will provide a unique and sensitive probe of the flavor dependence of quark helicity distributions and properties of the quark sea. Monte Carlo simulations of HERMES data for experiment asymmetries and polarized structure functions are discussed.
Date: December 31, 1994
Creator: Jackson, H.E.
Partner: UNT Libraries Government Documents Department

Calorimetry at 0{degree} in RHIC: Some issues in the choice of detector technology

Description: The authors discuss briefly the case for a zero degree calorimeter at RHIC and space constraints on such a device. Two GEANT simulations of quartz fiber calorimeters are then studied and compared to the corresponding case of scintillator sampling. The authors find that the Q-cal calorimeter does provide some improvement in response uniformity near the calorimeter edge to hadronic showers (due to the filtering out of wide angle shower products). This may be an advantage when space is limited and the calorimeter transverse dimensions are small.
Date: May 1, 1994
Creator: Christie, B.; White, S.; Gorodetzky, P. & Lazic, D.
Partner: UNT Libraries Government Documents Department

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

Composite particle production in relativistic Au+Au collisions at AGS: First results from the E866 forward spectrometer @ 2, 4, and 10.8 A{center_dot}GeV

Description: Particle spectra were measured for Au + Au collisions at 2, 4, and 10. 8 A{center_dot}GeV using the E866 spectrometers. Recent results on proton emission and composite particle production form the E866 forward spectrometer data taken in 1994 together with the first results from the 1995/6 AGS running period are presented. Preliminary results indicate a decrease in the coalescence scaling coefficient with increasing projectile energy and centrality.
Date: December 31, 1996
Creator: Ashktorab, K.
Partner: UNT Libraries Government Documents Department

Interesting aspects of the STAR detector and physics program

Description: The Solenoidal Tracker At RHIC (STAR) is a large acceptance collider detector scheduled to begin operation at the Relativistic Heavy Ion Collider (RHIC) in the fall of 1999. Simply stated, the physics goals of STAR are, (1) to study the behavior of strongly interacting matter at high energy density; (2) to search for signatures of a deconfined partonic phase of matter; and (3) to study the importance of spin as a fundamental property of QCD interactions and measure the spin-dependent parton distributions (gluon, valence quark, sea quark) of the proton. The detector design and methods of accomplishing the physics goals are addressed in this report.
Date: December 31, 1996
Creator: Hallman, T.J. & Collaboration, STAR
Partner: UNT Libraries Government Documents Department

Pion correlations and calorimeter design for high energy heavy ion collisions. Progress report

Description: Data analysis is in progress for recent experiments performed by the NA44 collaboration with the first running of 160 A GeV {sup 208}Pb-induced reactions at the CERN SPS. Identified singles spectra were taken for pions, kaons, protons, deuterons, antiprotons and antideuterons. Two-pion interferometry measurements were made for semi-central-triggered {sup 208}Pb + Pb collisions. An updated multi-particle spectrometer allows high statistics data sets of identified particles to be collected near mid-rapidity. A second series of experiments will be performed in the fall of 1995 with more emphasis on identical kaon interferometry and on the measurement of rare particle spectra and correlations. Modest instrumentation upgrades by TAMU are designed to increase the trigger function for better impact parameter selection and improved collection efficiency of valid events. An effort to achieve the highest degree of projectile-target stopping is outlined and it is argued that an excitation function on the SPS is needed to better understand reaction mechanisms. Analysis of experimental results is in the final stages at LBL in the EOS collaboration for two-pion interferometry in the 1.2 A GeV Au + Au reaction, taken with full event characterization.
Date: April 1, 1997
Creator: Wolf, K.L.
Partner: UNT Libraries Government Documents Department

Asymmetries in inclusive pion production at large x{sub F} = (0.5 to 0.8) and p{sub T} {ge} 0.8 GeV/c with a polarized beam for a RHIC polarimeter

Description: The authors propose to measure asymmetries in the inclusive reactions, using a transversely polarized beam, a liquid hydrogen target, and a carbon target. The measurements would be made using the 23-GeV/c proton beam in an extracted beam line from the AGS, a spectrometer consisting of an analyzing magnet, scintillation hodoscopes, scintillation trigger counters, and a gas threshold Cerenkov counter. The kinematic range covered by the experiments would be p{sub T} up to 1.0 GeV/c and x{sub F} = p*{sub L}/p*{sub max} {approx} 0.5 to 0.8. The purpose of this proposal is to obtain basic information in order to design a polarimeter for the RHIC polarized beams. The RHIC polarimeter is a crucial item for the success of the RHIC spin program.
Date: August 26, 1996
Creator: Krueger, K.; LeCompte, T. & Spinka, H.
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

Search for the B{sub c} meson in hadronic Z{sup 0} decays using the OPAL detector at LEP

Description: A search for decays of the B{sub c} meson was performed using data collected from 1990--1995 with the OPAL detector on or near the Z{sup 0} peak at LEP. The decay channels B{sub c}{sup +} {r_arrow} J/{psi}{pi}{sup +}, B{sub c}{sup +} {r_arrow} J/{psi}a{sub 1}{sup +} and B{sub c}{sup +} {r_arrow} J/{psi}{ell}{sup +}{nu} were investigated, where {ell} denotes an electron or a muon. Two candidates are observed in the mode B{sub c}{sup +} {r_arrow} J/{psi}{pi}{sup +}, with an estimated background of (0.63 {+-} 0.20) events. The weighted mean of the masses of the two candidates is (6.32 {+-} 0.06) GeV/c{sup 2}, which is consistent with the predicted mass of the B{sub c} meson. One candidate event is observed in the mode B{sub c}{sup +} {r_arrow} J/{psi}{ell}{sup +}{nu}, with an estimated background of (0.82 {+-} 0.19) events. No candidate events are observed in the B{sub c}{sup +} {r_arrow} J/{psi}a{sub 1}{sup +} decay mode, with an estimated background of (1.10 {+-} 0.22) events. Upper bounds at the 90% confidence level are set on the production rates for these processes.
Date: January 1, 1999
Creator: Herndon, M.F.
Partner: UNT Libraries Government Documents Department

Searches with taus at the Tevatron

Description: We discuss tau identification techniques at hadron colliders, and present the measurements and the searches performed so far. We report on top quark pair production in the decay channel containing at least one tau lepton. Also, we present results dedicated to searches for new particles, with taus in the final state. We present a search for the charged Higgs boson in the tau decay channel, as well as for the leptoquark family containing tau leptons. Finally, we indicate the capabilities of detecting and triggering on tau leptons in the future collider run.
Date: April 29, 1999
Creator: Gallinaro, M.
Partner: UNT Libraries Government Documents Department

CDF evidence for the top quark & B physics at Fermilab

Description: We present the first direct evidence for the top quark with the Collider Detector at Fermilab (CDF) in a sample of {bar p}p collisions at {radical}s=1.8 TeV with an integrated luminosity of 19.3 pb{sup -1}. The recent B physics results at Fermilab from both collider and fixed target experiments are reviewed.
Date: February 1, 1997
Creator: Yao, Weiming
Partner: UNT Libraries Government Documents Department

The gold flashlight: Coherent photons (and Pomerons) at RHIC

Description: The Relativistic Heavy Ion Collider (RHIC) will be the first heavy ion accelerator energetic enough to produce hadronic final states via coherent {gamma}{gamma}, {gamma}P, and PP interactions. Because the photon flux scales as Z{sup 2}, up to an energy of about {gamma}{h_bar}c/R {approx} 3 GeV/c, the {gamma}{gamma} interaction rates are large. RHIC {gamma}P interactions test how Pomerons couple to nuclei and measure how different vector mesons, including the J/{psi}, interact with nuclear matter. PP collisions can probe Pomeron couplings. Because these collisions can involve identical initial states, for identical final states, the {gamma}{gamma}, {gamma}P, and PP channels may interfere, producing new effects. The authors review the physics of these interactions and discuss how these signals can be detected experimentally, in the context of the STAR detector. Signals can be separated from backgrounds by using isolation cuts (rapidity gaps) and p{perpendicular}. The authors present Monte Carlo studies of different backgrounds, showing that representative signals can be extracted with good rates and signal to noise ratios.
Date: June 1, 1997
Creator: Klein, S. & Scannapieco, E.
Partner: UNT Libraries Government Documents Department