Bulletin of the American Physical Society
APS April Meeting 2010
Volume 55, Number 1
Saturday–Tuesday, February 13–16, 2010; Washington, DC
Session G7: Instrumentation for Relativistic Heavy Ion Physics |
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Sponsoring Units: DNP Chair: J.H. Lee, Brookhaven National Laboratory Room: Delaware A |
Sunday, February 14, 2010 8:30AM - 8:42AM |
G7.00001: The Forward Silicon Vertex Detector Upgrade for the PHENIX Experiment at RHIC Zhengyun You The PHENIX detector at RHIC will be upgraded with the Forward Silicon Vertex Detector (FVTX). The FVTX consists of two arms, each with four discs of silicon strip sensors combined with FPHX readout chips, covering the acceptance of existing muon arm detectors (1.2 $< \quad \vert $y$\vert \quad <$ 2.4). It will provide precision tracking and reconstruction of the primary vertex and the recognition of secondary decay vertices in the collision system, to allow discrimination among prompt muons, heavy flavor decay muons and muons from hadronic decays. The proposed tracker is planned to be put into operation in FY2011. The tracking performance and expectations for the physics signal extraction, the current status of detector construction, assembly plan, and the results of beam tests will be presented. [Preview Abstract] |
Sunday, February 14, 2010 8:42AM - 8:54AM |
G7.00002: Physics capability with silicon vertex tracker at RHIC PHENIX experiment Maki Kurosawa PHENIX is an experiment aiming to study the spin structure of proton and hot and dense matter at Brookhaven National Laboratory's Relativistic Heavy Ion Collider. The PHENIX detector will be upgraded with a silicon vertex tracker (VTX) to enhance it's physics capabilities for spin and heavy ion program. The VTX comprised of a four-layer barrel detector, two inner silicon pixel detectors and two outer silicon strip detectors. The main roles of the VTX are precision measurement of heavy flavor and precision jet reconstruction with it's large acceptance. In spin program, the VTX can determine x dependency of gluon polarization Delta-G/G through heavy flavor and gamma-jet correlation measurements. In heavy ion program, heavy flavor measurement provides further information on property of QGP in addition that from light flavor. This presentation provides overview of VTX upgrade and enhanced physics as well as current status of pixel detector. [Preview Abstract] |
Sunday, February 14, 2010 8:54AM - 9:06AM |
G7.00003: Status of the Muon Trigger Resistive Plate Chamber Upgrade Project in PHENIX Ihnjea Choi The exploration of proton spin structure is one of the major goals of the PHENIX experiment at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. Single longitudinal spin asymmetries for high momentum muons from W-boson decay at $\sqrt{s}=500$ GeV are a promising probe for the flavor decomposition of quark helicity distributions in the proton. The PHENIX muon trigger upgrade will provide the ability to select rare events with high momentum muons from the dominant background of low momentum muons from hadron decay. The upgrade consists of two components. (1) The existing muon spectrometer will be upgraded with new, fast trigger front-end electronics. (2) Fast Resistive Plate Chamber (RPC) stations will be added upstream and downstream of the two PHENIX muon spectrometers. In combination these upgrades make it possible to select high momentum tracks in the first level trigger and to reject beam related backgrounds. PHENIX muon trigger RPC technology, including the frontend electronics, follows closely the design of the CMS muon trigger RPCs. We report the status of the RPC upgrade project including the progress in detector assembly and RPC installation in the PHENIX muon spectrometers. [Preview Abstract] |
Sunday, February 14, 2010 9:06AM - 9:18AM |
G7.00004: Performance of PHENIX Resistive Plate Chambers Murad Sarsour The PHENIX experiment at the Relativistic Heavy Ion Collider at BNL uses polarized pp collisions to study the proton spin structure. One of the major emphases of the PHENIX spin program is to cleanly measure the sea quark and antiquark polarizations via single spin asymmetry of the W-decay muons. At forward rapidity, Resistive Plate Chambers (RPCs) will be used at PHENIX as a level-1 trigger to select high transverse momentum muon events from a large background of low transverse momentum muons. In addition, RPCs will be used offline to reduce cosmic muon backgrounds. Detector modules for one RPC station are currently being installed and tested at the PHENIX experimental site. In parallel, RPC prototypes are continuously monitored at a separate testing facility to study various environmental effects on the RPC performance. A report on results from these tests and performance will be presented. Results from the RPC prototype cosmic run to study the RPC's efficiency will also be presented. [Preview Abstract] |
Sunday, February 14, 2010 9:18AM - 9:30AM |
G7.00005: The PHENIX Muon Trigger Upgrade Level-1 Trigger System John Lajoie, Todd Kempel The PHENIX Muon Trigger Upgrade adds a set of Level-1 trigger detectors to the existing muon spectrometers and will enhance the ability of the experiment to pursue a rich program of spin physics in polarized proton collisions. The upgrade will allow the experiment to select high momentum muons from the decay of W bosons and reject both beam-associated and low-momentum collision background, enabling the study of quark and antiquark polarization in the proton. The Muon Trigger Upgrade will add momentum and timing information to the present muon Level-1 trigger, which only makes use of tracking in the PHENIX muon identifier (MuID) panels. Signals from new Resistive Plate Chambers (RPCs) and re-instrumented planes in the existing muon tracking (MuTr) chambers will provide momentum and timing information for the new Level-1 trigger. An RPC timing resolution of $\sim $2 ns will permit rejection of beam related backgrounds while tracking information from the RPCs and MuTr station will be used by the trigger to select events with high momentum muon candidates. The RPC and MuTr hit information will be sent by optical fibers to a set of Level-1 trigger processors that will make use of cutting edge FPGA technology to provide very high data densities in a compact form factor. The layout of the upgrade, details of the Level-1 electronics and trigger algorithm development will be presented. [Preview Abstract] |
Sunday, February 14, 2010 9:30AM - 9:42AM |
G7.00006: Status of the Silicon Stripixel Detector for PHENIX at RHIC Paul Kline A silicon vertex tracker upgrade is under development for the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). The detector consists of four barrel layers with $|\eta| < 1.2$ rapidity coverage. The two inner layers are pixel sensors (located 2.5cm and 5cm from the beam line) and the two outer layers are a novel stripixel sensor (at 10cm and 14cm). The detector will allow for an improvement in the primary vertex resolution, determination of secondary vertices from heavy quark production, and construction of jet direction based on particle multiplicities, improving the capabilities of both the heavy ion and spin programs at PHENIX. The current status of the stripixel detector will be presented. [Preview Abstract] |
Sunday, February 14, 2010 9:42AM - 9:54AM |
G7.00007: Performance studies of the Silicon Detectors in STAR towards microvertexing of rare decays Jonathan Bouchet Heavy quarks ($b$ and $c$) carrying hadron production as well as their elliptic flow can be used as a probe of the thermalization of the medium created in heavy ions collisions. Direct topological reconstruction of $D$, $B$ mesons and $\Lambda_{\mathrm{c}}$ baryon decays is then needed to obtain this precise measurement. To achieve this goal the silicon detectors of the STAR experiment are explored. These detectors, a Silicon Drift (SVT) 3-layer detector [1] and a Silicon Strip one-layer detector [2] provide tracking very near to the beam axis and allow us to search for heavy flavour with microvertexing methods. $D^{0}$ meson reconstruction including the silicon detectors in the tracking algorithm will be presented for the Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV, and physics opportunities will be discussed. \\[4pt] [1] R. Bellwied et al., \textit{Nucl. Inst. Methods} {\bf A499} (2003) 640. \\[0pt] [2] L. Arnold et al., \textit{Nucl. Inst. and Methods} {\bf A499} (2003) 652. [Preview Abstract] |
Sunday, February 14, 2010 9:54AM - 10:06AM |
G7.00008: The possibility of a Very High Momentum Particle Identification upgrade for Alice Edmundo Garcia The results of RHIC have strongly altered the perception of the baryon production in heavy-ion collisions. From a proton over pion ratio of 9{\%} in the thermal region, above transverse momenta of 3 GeV/c this ratio equals or even surpasses unity. Several theoretical predictions for LHC assume an enhanced baryon production at higher transverse momenta: 10-20 GeV/c. In that optics we have decided to propose to the ALICE collaboration an upgrade of the particle identification capabilities with a new detector of small size 12 square meters. In the first stage we consider building a prototype to be commissioned at the end of 2011. The prototype would consist of a C4F10 gas Cherenkov detector with spherical mirror focusing, and CsI photocathode coupled with MWPCs. The detector would identify pions and kaons up to a momentum of 26 GeV/c with a 4 sigma separation. We will discuss also the possible use of GEMs as a photo detector where encouraging results have been obtained by our protocollaboration. The physics capabilities of such a detector in conjunction with the ALICE experiment will be contemplated. [Preview Abstract] |
Sunday, February 14, 2010 10:06AM - 10:18AM |
G7.00009: Local Polarimetry at STAR Using the Zero Degree Calorimeter Shower Maximum Detector Alice Bridgeman The polarized proton program at the Relativistic Heavy Ion Collider (RHIC) began colliding beams at a center of mass energy of 500 GeV in 2009, after successful running at a center of mass energy of 200 GeV in previous years. The polarized beams are monitored locally at STAR using various local polarimeters. At 200 GeV, the Beam Beam Counter (BBC) detectors have a sufficiently large analyzing power to work effectively as local polarimeters. At 500 GeV, the BBCs showed a decreased analyzing power. In 2009 the STAR collaboration successfully commissioned the Zero Degree Calorimeter (ZDC) with Shower Maximum Detector (SMD) for use as a local polarimeter at 500 GeV. I will review the work done in this run and discuss plans for the ZDC SMD in future polarized proton running at 500 GeV at STAR. [Preview Abstract] |
Sunday, February 14, 2010 10:18AM - 10:30AM |
G7.00010: Heavy Flavor Physics in Heavy-Ion Collisions with STAR Heavy Flavor Tracker Yifei Zhang Heavy quarks are a unique tool to probe the strongly interacting matter created in relativistic heavy-ion collisions at RHIC energies. Due to their large mass, energetic heavy quarks are predicted to lose less energy than light quarks by gluon radiation when they traverse a Quark-Gluon Plasma. In contrast, recent measurements of non-photonic electrons from heavy quark decays at high transverse momentum (p$_{T})$ show a jet quenching level similar to that of the light hadrons. Heavy quark are produced mainly at early stage in heavy-ion collisions, thus they are proposed to probe the QCD medium and to be sensitive to bulk medium properties. Ultimately, their flow behavior may help establish whether light quarks thermalize. Therefore, topological reconstruction of D-mesons and identification of electrons from charm and bottom decays are crucial to understand the heavy flavor production and their in medium properties. The Heavy Flavor Tracker (HFT) is a micro-vertex detector utilizing active pixel sensors and silicon strip technology. The HFT will significantly extend the physics reach of the STAR experiment for precise measurement of charmed and bottom hadrons. We present a performance study with full detector on the open charm nuclear modification factor, elliptic flow v$_{2}$ and $\Lambda _{c}$ measurement as well as the measurement of bottom mesons via a semi-leptonic decay. [Preview Abstract] |
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