Extending physics capabilities of the PHENIX detector with calorimetry at forward rapidities

The PHENIX detector at RHIC has been designed to study different signatures of the states of matter created in heavy-ion collisions, and to investigate the spin structure of the nucleon. The PHENIX detector measures muons in two muon spectrometers, located at forward rapidities (1.2 < |η| < 2.4) and hadrons, electrons and photons in the two central spectrometers at midrapidity (|η| <0.35). To make a next step in the PHENIX research program, it is necessary to extend the rapidity coverage beyond the limits set by the existing central spectrometer. The functionality of the PHENIX muon detectors can be extended with added capabilities to measure photonic and hadronic jets. Tungsten calorimeters with silicon pixel readout and fine transverse and longitudinal segmentation are proposed to attain this goal. The proposed calorimeters will be located in the forward directions on either side of the PHENIX interaction point. In this talk we report on the studies of the functionality of the proposed calorimeters: the detector energy resolution, the jet reconstruction capabilities and the characteristics of pion rejection.     

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 of the PHENIX silicon pixel detector

The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) is being upgraded with a novel four-layer silicon vertex tracker. The detector will enhance the physics capabilities of PHENIX in the future phase of the heavy-ion and the polarized proton-proton programs at RHIC. The silicon vertex tracker will allow the direct measurement of heavy quark production by identifying displaced decay vertices, and will reconstruct jets with nearly full azimuthal coverage over |η| < 1.2. We are developing a novel Silicon Pixel Detector for the inner two barrel layers of the silicon vertex tracker. In this paper, the status of the development is reported. 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.     

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.     

The laser calibration system of the ALICE time projection chamber

A Large Ion Collider Experiment (ALICE) is the only experiment at the Large Hadron Collider (LHC) dedicated to the study of heavy ion collisions. The Time Projection Chamber (TPC) is the main tracking detector covering the pseudo rapidity range |η| < 0.9. It is designed for a maximum multiplicity dN/dy = 8000. The aim of the laser system is to simulate ionizing tracks at predifined positions throughout the drift volume in order to monitor the TPC response to a known source. In particular, the alignment of the read-out chambers will be performed, and variations of the drift velocity due to drift field imperfections can be measured and used as calibration data in the physics data analysis. In this paper we present the design of the pulsed UV laser and optical system, together with the control and monitoring systems. for the ALICE Collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

Hadron production at forward and backward rapidities in \sqrt {s_{NN} } = 200 GeV d+Au collisions

Understanding normal nuclear medium effects present in heavy ion collisions is essential for understanding the following dynamics of the high density matter produced in the collision. Asymmetric collisions, such as deuteron + gold, provide a key tool for studying these effects since particles produced in the forward and backward directions may be subject to different phenomena. Particle production has been studied in d+Au collisions for various kinematic regions at the RHIC facility. PHENIX has measured charged hadron production as a function of pT for different centrality classes using the PHENIX muon spectrometers for d+Au collisions at $\sqrt {s_{NN} } = 200$ GeV. The PHENIX muon spectrometers have coverage in both forward and backward directions in the rapidity range 1.2 |η| < 2.4. The R _cp measurement, the ratio of central to peripheral production, is presented and discussed. Comparisons are also made with some relevant theoretical calculations.     

Beam test performance of prototype assemblies for the ALICE Silicon Pixel Detector

The silicon pixel detector (SPD) comprises the two innermost layers of the inner tracking system oft he ALICE experiment at LHC. Prototype SPD assemblies have been tested in high-energy proton and pion beams at the CERN SPS. The method used for data analysis and the most relevant results in relation to detector performance are presented. Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005. On behalf of the Silicon Pixel Detector project in the ALICE Collaboration     

Measuring beauty production in Pb-Pb collisions at the LHC via single electrons in ALICE

We present the expected ALICE performance for the measurement of the p _t-differential cross section of electrons from beauty decays in central Pb-Pb collisions at the LHC. for the ALICE Collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

J/<Emphasis Type="Italic">ψ</Emphasis> production measurements by the PHENIX experiment

Quarkonia suppression is considered to be one of the key probes of the Quark Gluon Plasma (QGP) created in heavy ion collisions. The PHENIX experiment has measured J/ψ production in a variety of colliding systems. Measurements made in p+p collisions show good agreement with pQCD predictions and serve as baseline for other systems at the same collision energy. The cold nuclear matter contribution to the suppression is constrained through measurements in d+Au collisions. In Au+Au, the suppression observed at mid rapidity is smaller than that at forward rapidity, a tendency opposite to what is expected from the higher gluon density at mid rapidity. The results will be presented and discussed in this article.     

Study of Muons in Ultra-High-Energy Cosmic-Ray Air Showers with the Telescope Array Experiment

One of the uncertainties in the interpretation of ultra-high-energy cosmic-ray (UHECR) data comes from the high-energy hadronic interaction models used for air shower Monte-Carlo (MC) simulations. A long-standing problem of the so-called “muon excess”, the discrepancy of number of muons predicted by simulations and observed in the data, is believed to be caused by the incompleteness of modern hadronic interaction models, all of which are known to use the extrapolated values of the parameters of hadronic interactions, such as cross sections and multiplicities. The present work is dedicated to the study of muon densities in UHE extensive air showers from the Telescope Array experiment surface detector data. In the 7-year-data from the Telescope Array experiment, we find that the number of particles observed for signals with an expected muon purity of ∼65% at a lateral distance of 2000 m from the shower core is 1.72 ± 0.10(stat.) ± 0.37(syst.) times larger than the MC prediction value using the QGSJETII-03 model for the proton-induced showers. A similar effect is also seen in comparison with other hadronic models such as QGSJETII-04, which shows a 1.67 ± 0.10 ± 0.36 excess. We also studied the dependence of these excesses on lateral distances and found a slower decrease of the lateral distribution of muons in the data as compared to the MC, causing larger discrepancy at the larger lateral distances.     

Muon content of ultrahigh-energy air showers: Yakutsk data versus simulations

A sample of 33 extensive air showers (EASs) with estimated primary energies above 2 × 10¹⁹ eV and high-quality muon data recorded by the Yakutsk EAS array is analyzed. The observed muon density is compared event-by-event to that expected from CORSIKA simulations for primary protons and iron using SIBYLL and EPOS hadronic interaction models. The study suggests the presence of two distinct hadronic components, “light” and “heavy.” Simulations with EPOS are in good agreement with the expected composition in which the light component corresponds to protons and the heavy component to iron-like nuclei. With SIBYLL, simulated muon densities for iron primaries are a factor of ∼ 1.5 less than those observed for the heavy component for the same electromagnetic signal. Assuming a two-component proton-iron composition and the EPOS model, the fraction of protons with energies E > 10¹⁹ eV is 0.52_−0.20^+0.19 at the 95% C.L. The text was submitted by the authors in English.     

A high-performance silicon tracker for the Compressed Baryonic Matter experiment at FAIR

The Compressed Baryonic Matter (CBM) experiment is a fixed-target heavy-ion experiment planned at GSI's future international Facility for Antiproton and Ion Research (FAIR). CBM will study strongly interacting matter at high baryon densities where the QCD phase diagram is poorly known. The experiment applies a detector concept new to heavy-ion physics: All charged particles as well as secondary vertices from heavy-flavor decays are exclusively reconstructed in a high-performance silicon tracking system. It will be installed in a magnetic dipole field between the target and further detection systems for particle identification and calorimetry. High track densities and high collision rates require the application of most advanced silicon detectors. The technological challenges include high position resolution in thinnest possible pixel and microstrip sensors, combined with extreme radiation hardness, fast self-triggered readout and ultra low-mass mechanical supports. The article outlines the physics and detector concept of CBM and discusses the performance requirements of the silicon tracker and the beginning R&D. for the CBM collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

The 4th concept detector

The 4th concept detector consists of four detector subsystems, a small-pixel vertex detector, a high-resolution TPC, a new multiple-readout fiber calorimeter and a new dual-solenoid iron-free muon system. We discuss the design of a comprehensive facility that measures and identifies all partons of the standard model, including hadronic W → jj and Z → jj decays, with high precision and high efficiency. We emphasis here the calorimeter and muon systems.      

Partial restoration of chiral symmetry of vector mesons in hot hadronic matter: a possible signature of quark-gluon plasma

A φ meson is an excellent candidate to see the dynamical and critical phenomena at finite temperature of hadronic and quark matter which can be produced through relativistic nucleus-nucleus collisions. PHENIX Collaboration and Chairperson of the PHENIX-J Collaboration.     

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.     

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.     

Nucleus-nucleus collisions at ultra-relativistic energies: Status and prospects

Physics with ultra-relativistic heavy ions at three different accelerators SPS at CERN and AGS and RHIC at BNL is reviewed. The physics discussed ranges from global event characteristics through direct photon production, proton-proton correlation studies to Quark Gluon Plasma (QGP) phase trasition signatures via dileptonic, photonic and hadronic signals.Invited lecture given at the International School-Workshop Relativistic Heavy-Ion Physics, Prague (Czech Republic), 19–23 September 1994.Managed by Martin Marietta Energy Systems, Inc., under contract DE-AC05-84OR21400 with the U.S. Department of Energy.In conclusion, I have indicated that the RHIC project is well underway, and that the two major experiments planned for the facility, PHENIX and STAR, are being implemented with broad capabilities to address future exciting physics issues. A strong argument can be made that European groups should join the RHIC effort even with the advent of the LHC project at CERN. Aside from covering different energy regions, the two projects are shifted in time by over five years relative to each other, and RHIC is a machine dedicated to nucleus-nucleus studies, while the LHC will be available only on a limited basis.     

B-hadron cross-section measurement in pp collisions at $\sqrt{s}=14$ TeV with the ALICE muon spectrometer

ALICE (A Large Ion Collider Experiment) is the LHC detector designed to measure nucleus-nucleus (AA) collisions where the formation of the Quark Gluon Plasma is expected. The experiment will also study proton-proton (pp) collisions at 14 TeV. Amongst the relevant observables to be investigated in pp collisions, the B-hadron cross-section is particularly interesting since it provides benchmarks for theoretical models and it is mandatory for understanding heavy flavour production in AA collisions. The performances of the ALICE muon spectrometer to measure B-hadron cross-section in pp collisions at 14 TeV via single muons are presented.     

The origin of thermal hadron production

Multihadron production in high energy collisions, from e⁺e^- annihilation to heavy ion interactions, shows remarkable thermal behaviour, specified by a universal “Hagedorn” temperature. We argue that this hadronic radiation is formed by tunneling through the event horizon of colour confinement, i.e., that it is the QCD counterpart of Hawking-Unruh radiation from black holes. It is shown to be emitted at a universal temperature T_H ≃ (σ/2 π)^1/2, where σ denotes the string tension. Since the event horizon does not allow information transfer, the radiation is thermal “at birth”.