Bulletin of the American Physical Society
2005 APS April Meeting
Saturday–Tuesday, April 16–19, 2005; Tampa, FL
Session M13: Ultrarelativistic Heavy Ion Collisions III |
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Sponsoring Units: DNP Chair: Marco van Leeuwen, LBNL Room: Marriott Tampa Waterside Room 12 |
Sunday, April 17, 2005 3:15PM - 3:27PM |
M13.00001: $J/\Psi \rightarrow \mu^{+}\mu^{-}$ Measurement by the PHENIX in Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV MinJung Kweon The modification of heavy quarkonium yields and spectra is one of the most promising candidates to probe the nuclear phase transition from the confined hadron gas to the deconfined quark- gluon plasma. The PHENIX experiment at RHIC is designed to study heavy quarkonium production via the dilepton channels ($e^ {+}e^{-}$ and $\mu^{+}\mu^{-}$) with high precision. During the run 4, PHENIX has, for the first time, accumulated significant statistics for $J/\Psi$ production in Au+Au collisions at $\sqrt {s_{NN}}$=200 GeV. We report the first results on the $J/ \Psi\rightarrow \mu^{+}\mu^{-}$ production measured in the PHENIX muon spectrometers, covering $1.2 < \eta < 2.4$ and $- 1.2 < \eta < -2.2$. [Preview Abstract] |
Sunday, April 17, 2005 3:27PM - 3:39PM |
M13.00002: Single Muon Production in Cu+Cu Collisions at $\sqrt{s_{NN}}=200\ GeV$ Irakli Garishvili The PHENIX experiment at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory with its muon spectrometer has the ability to detect muons over the range of $1.1 > | \eta | > 2.25$. In the experimental run starting in January 2005 (Run 5), the experiment began collecting the first $Cu+Cu$ collisions at $\sqrt{s_{NN}} =200\GeV$. Single muon production is an important tool for studying charm production via semi-leptonic decays of D mesons. Open charm production not only contains rich physics itself, but also is considered to be one of the most important probes of the Quark Gluon Plasma, which is predicted to be created in relativistic heavy ion collisions. The present status of single muon studies for Run-5 Cu+Cu data by the PHENIX Collaboration will be presented and compared with previous single muon studies for p+p and Au+Au collisions. [Preview Abstract] |
Sunday, April 17, 2005 3:39PM - 3:51PM |
M13.00003: Nuclear Modification Factors for Hadrons At Forward and Backward Rapidities in Deuteron-Gold Collisions at $\sqrt{s_{NN}} = 200 $GeV Chun Zhang We report on charged hadron production in deuteron-gold reactions at $\sqrt{s_{NN}} = 200$ GeV. Our measurements in the deuteron-direction cover $1.4 < \eta < 2.2$, referred to as forward rapidity, and in the gold-direction $-2.0 < \eta < -1.4 $, referred to as backward rapidity, and a transverse momentum range $p_T = 0.5 - 4.0$ GeV/c. We compare the relative yields for different deuteron-gold collision centrality classes. We observe a suppression relative to binary collision scaling at forward rapidity, where the measurement is sensitive to low momentum fraction (x) partons in the gold nucleus, and an enhancement at backward rapidity, sensitive to high momentum fraction partons in the gold nucleus. [Preview Abstract] |
Sunday, April 17, 2005 3:51PM - 4:03PM |
M13.00004: The Dependence of the Energy Loss of Hard-Scattered Partons on the Geometry of the Collision Saskia Mioduszewski The suppression of high $p_T$ hadrons has been one of the most significant discoveries at RHIC. It has been interpreted as energy loss of hard-scattered partons in the dense matter created in Au+Au collisions. Due to the pure power-law spectrum of pions for $p_T > 3$ GeV/c and the observed constancy of the suppression factor, the suppression can be characterized by a constant fractional energy loss per particle. In an effort to gain understanding of the energy loss, the dependence on the geometry of the collision is investigated via the azimuthal asymmtery ($v_2$) of emitted particles. The fractional energy loss is shown as a function of the emission angle with respect to the reaction plane as well as the centrality of the collision. An attempt to disentangle the effects of the collision geometry and the energy density on the energy loss will be presented. [Preview Abstract] |
Sunday, April 17, 2005 4:03PM - 4:15PM |
M13.00005: $\phi$ meson measurement via $K^{+}K^{-}$ decay channel in d+Au collisions at$\sqrt{s_{NN}}$= 200 GeV Dipali Pal The measurement of the line shape of the $\phi$ meson invariant mass spectrum in relativistic heavy ion collisions is a powerful tool to search for in-medium modifications of vector meson properties (mass and/or width) as chiral symmetry restoration is approached. Consisting of a $s\bar{s}$ pair, the $\phi$ meson can also be used to probe strangeness production. The current results of $\phi$ meson production in the $K^{+}K^{-}$ channel detected by the PHENIX central arm spectrometer in d+Au collisions will be presented. The system size and centrality dependece of the $\phi$ spectral shapes and yields will be studied through the comparison with results obtained in Au+Au and p+p collisions. [Preview Abstract] |
Sunday, April 17, 2005 4:15PM - 4:27PM |
M13.00006: Transverse momentum spectra from PHOBOS at RHIC Edward Wenger The PHOBOS experiment has obtained transverse momentum distributions for charged hadrons and identified hadrons in nuclear collisions at RHIC. The spectra were studied as a function of system size in d+Au and Au+Au collisions at 200 GeV/nucleon, and also as a function of collision energy in Au+Au. In this talk, a systematic survey of recent data will be compared with predictions of various models, with particular emphasis on the intermediate and high $p_T$ regions. [Preview Abstract] |
Sunday, April 17, 2005 4:27PM - 4:39PM |
M13.00007: Measurement of Direct Photon Production in p+p Collisions at $\sqrt{s} = 200$ GeV Stefan Bathe The measurement of high-momentum direct photons in nucleus-nucleus collisions is an excellent test of QCD: Photons are a direct participant of the fundamental interaction, they are not affected by constituent scattering, they do not undergo fragmentation, and they can be measured to high precision. In A+A collisions, direct photon production is an important observable in the search for the Quark-Gluon Plasma. To obtain the contribution of pQCD photons to the total photon signal, it is crucial to measure the signal in p+p collisions. With RHIC's ability to collide polarized proton beams, direct photons in p+p will also be the key probe of the gluon spin structure function of the proton. With its high-granularity electromagnetic calorimeter and triggering capability, the PHENIX experiment is superbly suited for measuring direct photons. The status of the measurement of direct photon production in p+p collisions will be presented. [Preview Abstract] |
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