Bulletin of the American Physical Society
2005 TSAPS/AAPT/SPS Joint Fall Meeting
Thursday–Saturday, October 20–22, 2005; Houston, TX
Session D4: Particle Physics |
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Room: Barron's S109 |
Friday, October 21, 2005 4:00PM - 4:12PM |
D4.00001: Cosmic ray test system for a multigap resistive plate chamber (MRPC)--based time-of-flight subsystem (TOF) for the STAR Detector at RHIC Kohei Kajimoto Research and development for a time-of-flight (TOF) subsystem for the STAR detector at RHIC has been underway for the past several years. The TOF system will utilize multigap resistive plate chambers (MRPC) whose excellent time resolution (velocity determination), together with STAR’s Time Projection Chamber (TPC) track information (momentum determination), will considerably extend particle identification capability of STAR to higher momentum over large angular acceptance. We have constructed a cosmic ray test system comprised of three plastic scintillators, 4 MRPC modules, and TOF prototype electronics in order to investigate the timing resolution that will be characteristic of the entire TOF system. The test setup will be discussed, test data will be described, and the timing analysis technique will be presented. Overall timing resolution of $\sim$90~ps for cosmic ray events has been achieved. [Preview Abstract] |
Friday, October 21, 2005 4:12PM - 4:24PM |
D4.00002: Pion-Nucleon Charge Exchange in the N*(1440) Resonance Region Michael Sadler, Shon Watson Results for pion-nucleon charge exchange scattering at eight laboratory momenta from 355 to 659 MeV/c will be reported from the Crystal Ball Collaboration at Brookhaven National Laboratory. The results agree well with the GWU FA02 partial wave analysis but differences exist at the backward angles at higher momenta. These data complement previously reported measurements made by the Crystal Ball Collaboration of all-neutral final states in the first and second resonance regions (charge exchange near the Delta(1232) and near eta threshold, eta production, multiple pi-zero final states, and inverse photoproduction). An overview of these data will be presented and arguments for reevaluating the accepted resonance parameters for the N*(1440) will be made. [Preview Abstract] |
Friday, October 21, 2005 4:24PM - 4:36PM |
D4.00003: Two-particle number and transverse momentum correlations in Au-Au collisions at $\sqrt{s_{NN}}$ = 62.4 and 200 GeV Michael Daugherity A novel, minimally-biased two-particle correlation analysis of relativistic heavy-ion collisions is presented. Autocorrelations on relative pseudorapidity and azimuth are determined from analysis of STAR data for Au-Au collisions at $\sqrt{s_{NN}}$ = 62.4 and 200 GeV. The analysis method is extended from correlations on the number of pairs of particles to correlations on transverse momentum, and the results are compared and contrasted. Since this analysis does not require a high-$p_t$ trigger, correlation structures associated with both (minimum-bias) jets and the bulk medium are observed. These structures are shown to evolve with centrality and energy in a way consistent with initial-state partonic scattering followed by strong interactions with the medium. [Preview Abstract] |
Friday, October 21, 2005 4:36PM - 4:48PM |
D4.00004: Application of two-point correlation and autocorrelation methods to the analysis of p-p and Au-Au collision data from STAR Robert Ray Analyses of relativistic heavy-ion collision data which obtain global information, such as the distribution and kind of particles produced, characteristic lengths of the collision system, average energy production, etc. report observables which reflect the aggregate result of a complex sequence of dynamical processes. Novel measurement quantities have been developed and applied to STAR data [1] which display more directly specific effects of the underlying dynamical processes, for example momentum dissipation and transport, color transport by way of minimum-bias jet-like structures (minijets), and evolution of hadronization geometry with collision centrality. Our results include: (1) large momentum scale correlations of the number of pairs of particles on transverse momentm ($p_t$), pseudorapidity ($\eta$), and azimuth ($\phi$), (2) two-point (bin-to-bin) correlations of $p_t$ on ($\eta,\phi$) subspace, and (3) event-wise fluctuations of multiplicity, net charge, $p_t$, etc. as functions of ($\eta,\phi$) bin size (scale). Examples will be shown and dominant features of the correlations interpreted for p-p and Au-Au collision data from STAR. [1] J. Adams et al. (STAR Collaboration), nucl-ex/0408012; nucl-ex/0411003; nucl-ex/0406035. [Preview Abstract] |
Friday, October 21, 2005 4:48PM - 5:00PM |
D4.00005: Proposed STAR time of flight readout electronics and DAQ Joachim Schambach A novel Time-of-Flight (TOF) system is a proposed addition to the STAR detector currently installed at RHIC. The system is based on the new technology of the Multi-gap Resistive Plate Chamber (MRPC), and consists of approximately 23,000 channels of detectors distributed over 120 trays. Each TOF tray consists of 192 detector channels and three different types of electronic circuit cards, called “TINO”, “TDIG”, and “TCPU”, listed in order of the data flow. Every thirty trays connect to a “THUB” card that transmits the data over a fiber to a PCI receiver in a PC which is part of STAR DAQ. The TINO contains the analog front end electronics. The output of TINO is passed to the TDIG, where the data are digitized (using the CERN HPTDC ASIC). The TCPU formats the digital detector information. These formatted data are passed to THUB, which buffers the data and transmits it over an optical fiber to a PC in the STAR DAQ room in response to Level-2 trigger commands. The architecture of this readout chain and DAQ will be described, and first results from prototypes of the component boards will be discussed. [Preview Abstract] |
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