Charged-particle multiplicity at mid-rapidity in Au-Au collisions at relativistic heavy-ion collider

The particle density at mid-rapidity is an essential global variable for the characterization of nuclear collisions at ultra-relativistic energies. It provides information about the initial conditions and energy density reached in these collisions. The pseudorapidity densities of charged particles at mid-rapidity in AuAu collisions at √^s _NN = 130 and 200 GeV at RHIC (relativistic heavy ion collider) have been measured with the PHENIX detector. The measurements were performed using sets of wire-chambers with pad readout in the two central PHENIX tracking arms. Each arm covers one quarter of the azimuth in the pseudorapidity interval |η| < 035. Data is presented and compared with results from proton-proton collisions and nucleus-nucleus collisions at lower energies. Extrapolations to LHC energies are discussed.     

A fast muon trigger for the PHENIX forward spectrometer upgrade

The PHENIX forward upgrade adds nosecone calorimeters and level-1 trigger (LVL-1) detectors to the muon forward spectrometers. The muon detector will trigger on high pT muons from W decay and reject background. This will enable study of quark and anti-quark polarizations in the proton. The upgrade will add momentum and timing information to the present muon trigger. Signals from 3 Resistive Plate Chambers (RPCs) will provide momentum and timing information for the LVL-1 trigger. Each RPC carries a plane with coarse structure to establish a space point for timing and one with radial cathode strips for azimuthal resolution. Timing resolution of ≈ 2 ns rejects beam-related backgrounds and tracking from RPCs minimizes muons from hadron decays. RPC information is sent by optical. bers to LVL-1 trigger processors. A discussion of physics measurements possible, layout of the upgrade and details of RPC design and tests are given below. for the PHENIX collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

Development and testing of novel stripixel detectors for the silicon vertex tracker at PHENIX

As a part of the upgrades for the PHENIX detector at RHIC,a silicon vertex tracking detector is planned. This detector will consist of two pixel layers followed by two strip-pixel layers in the barrel region,an d four mini-strip layers in the endcap region. As a part of the development phase of the vertex detector, we have set up three sensor testing facilities at Brookhaven National Laboratory, at State University of New York, Stonybrook, and at University of New Mexico to characterize the preproduction sensors, and develop our testing and quality assurance plans. Preliminary results from these test are presented here. Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

Status of the quark gluon plasma search

A selection of results are discussed that support the conclusion that strongly interacting quark gluon plasma is produced in heavy-ion collisions at the Relativistic Heavy Ion Collider at BNL.     

The PHENIX forward spectrometer upgrade

The forward spectrometer upgrade of the PHENIX detector aims to add capabilities at forward rapidities to: probe nucleon structure through W production and promptphotons in polarized p + p, study nucleon structure in nuclei at high parton densities in p + A collisions through the measurement of γ and π⁰ in the forward region, greatly extend the acceptance for high p _T γ-jet measurements (jet tomography) in A + A, and increase our capabilities to measure the production quarkonium states by giving sensitivity to the χ _c through the J/ψ + γ channel. for the PHENIX Forward Upgrade Collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

First results from RHIC-PHENIX

The PHENIX experiment consists of a large detector system located at the newly commissioned relativistic heavy ion collider (RHIC) at the Brookhaven National Laboratory. The primary goal of the PHENIX experiment is to look for signatures of the QCD prediction of a deconfined high-energy-density phase of nuclear matter quark gluon plasma. PHENIX started data taking for Au+Au collisions at √sNN=130 GeV in June 2000. The signals from the beam-beam counter (BBC) and zero degree calorimeter (ZDC) are used to determine the centrality of the collision. A Glauber model reproduces the ZDC spectrum reasonably well to determine the participants in a collision. Charged particle multiplicity distribution from the first PHENIX paper is compared with the other RHIC experiment and the CERN, SPS results. Transverse momentum of photons are measured in the electro-magnetic calorimeter (EMCal) and preliminary results are presented. Particle identification is made by a time of flight (TOF) detector and the results show clear separation of the charged hadrons from each other. For the PHENXI Collaboration The word PHENIX is the abbreviation of Pioneering High Energy Nuclear Interaction Experiment.