G. David

Proton and pion production relative to the reaction plane in Au + Au collisions at 11A GeV/c

Results are presented of an analysis of proton and charged pion azimuthal distributions measured with respect to the reaction plane in Au + Au collisions at a beam momentum of about 11A GeV/c. The azimuthal anisotropy is studied as a function of particle rapidity and transverse momentum for different centralities of the collisions. The triple differential (in rapidity, transverse momentum, and azimuthal angle) distributions are reconstructed. A comparison of the results with a previous analysis of charged-particle and transverse energy flow as well as with model predictions are presented. {copyright} {ital 1997} {ital The American Physical Society}

Proton and pion production in Au+Au collisions at 10.8A GeV/c

We present proton and pion tranverse momentum spectra and rapidity distributions for Au+Au collisions at 10.8A GeV/c. The proton spectra exhibit collective transverse flow effects. Evidence of the influence of the Coulomb interaction from the fireball is found in the pion transverse momentum spectra. The data are compared with the predictions of the RQMD event generator.

Event reconstruction in the PHENIX central arm spectrometers

The central arm spectrometers for the PHENIX experiment at the Relativistic Heavy Ion Collider have been designed for the optimization of particle identification in relativistic heavy ion collisions. The spectrometers present a challenging environment for event reconstruction due to a very high track multiplicity in a complicated, focusing, magnetic field. In order to meet this challenge, nine distinct detector types are integrated for charged particle tracking, momentum reconstruction. and particle identification. The techniques which have been developed for the task of event reconstruction are described.

Performance of the PHENIX EM Calorimeter

The PHENIX Electromagnetic Calorimeter is a large 15,552 channel lead/scintillator sampling calorimeter based on the shish-kebab optical readout technique. In this report we summarize studies leading to an optimal design for measurement of photons and electrons in the 1 GeV momentum range within the high multiplicity environment expected for events at RHIC. Timing resolutions of /spl sim/100 ps and a sampling dominated energy resolution of 8% at 1 GeV are featured. We also present a novel scheme for monitoring gain and timing of our entire system. Test results with a 144 channel preproduction super-module exposed to electron and hadron beams at the AGS are described. The calorimeter is currently under construction in Russia and the US and will be fully installed at RHIC during 1998.

The PHENIX lead-scintillator electromagnetic calorimeter: test beam and construction experience

We have recently completed the production of the 15552 channel lead-scintillator electromagnetic calorimeter for the PHENIX experiment at RHIC. Our design features a single 4 tower module which is repeated throughout and which was produced with a number of quality control steps designed to achieve consistent, large light yields in all channels. We present results on the uniformity of the calorimeter, accuracy of a cosmic muon based precalibration scheme and test beam performance.

Light fragment yields from central Au+Au collisions at 11.5A GeV/c

Inclusive double differential multiplicities of deuterons, {sup 3}H, {sup 3}He, and {sup 4}He measured by E877 for 11.5A GeV/c Au+Au collisions at the Brookhavens Alternating Gradient Synchrotron (AGS) are presented. Light fragments at beam rapidity are measured for the first time at AGS energies. Beam rapidity deuteron and {sup 4}He yields and transverse slope parameters are found to be strongly dependent on the impact parameter, and the shape of the deuteron spectra is not consistent with that expected for a simple thermal distribution. The deuteron yields relative to proton yields are analyzed in terms of a simple coalescence model. While results indicate an increase in source size compared to collisions of lighter systems at the same energy, they are inconsistent with a simple coalescence model reflected by a rapidity dependence of the coalescence parameter B{sub d}. A new approach utilizing an expanding thermalized source combined with a coalescence code is developed for studying deuteron formation in heavy-ion collisions. The strong dependence of deuteron yields on collective motion implies that deuteron yields relative to those of protons can be used for constraining source parameters. (c) 2000 The American Physical Society.

Performance studies of a new Russian FEU115M phototube

We report on the results of tests of FEU115M one inch phototubes manufactured in Russia. The tubes are 12-stage, fast devices with high gain and low dark current. These photomultiplier tubes were developed for the PHENIX EMCal project by members of the PHENIX group at IHEP, Protvino (Russia). We report on investigations of the gain, quantum efficiency, linearity, photocathode uniformity and long-term behavior of these tubes. >

Prototype tests of a high resolution electromagnetic calorimeter using undoped cesium iodide crystals

Abstract A prototype detector for a high resolution electromagnetic calorimeter for the PHENIX experiment at RHIC has been built and tested. The detector consists of a 6 × 5 array of undoped cesium iodide crystals read out with photomultiplier tubes or vacuum phototetrodes. The response for electrons and pions was measured in the momentum range from 50 MeV/ c to 4 GeV/ c in several beam tests at Brookhaven and TRIUMF. The energy resolution for electrons can be parameterized as σ ( E )/ E = 1.8%/√ E ⊕ 0.3%/ E ⊕ 0.8%, where E is in GeV, and the position resolution as σ x (mm) = 4.7/√ E + 0.5. The π/e separation was determined to be in the range from 10 −2 at 100 MeV/ c to a few times 10 −3 at 4 GeV/ c . The time resolution was measured to be 127 ps for 150 MeV/ c electrons after correcting for start counter timing. A laser calibration system is also described, along with the expected performance of the detector in the high multiplicity environment anticipated for relativistic heavy ion collisions at RHIC.

Pattern recognition in the PHENIX PbSc electromagnetic calorimeter

The pattern recognition algorithm for the PHENIX PbSc electromagnetic calorimeters are presented. The algorithm is based upon energy and impact angle dependent description of the electromagnetic shower shape as measured in the test beam and reproduced in GEANT simulation. The efficiency of the pattern recognition for identification of single and multiple showers is studied and discussed.

The calibration and monitoring system for the PHENIX lead-scintillator electromagnetic calorimeter

The calibration and monitoring system for the PHENIX lead-scintillator electromagnetic calorimeter is described along with the experience obtained in using this system to calibrate calorimeter modules with cosmic rays. The system is based on a UV laser which delivers light to each module through a series of optical fibers and splitters that is monitored at various points using silicon and vacuum photodiodes. Results are given from a prototype system based on a nitrogen laser which was used to monitor the stability of several modules, as well as to set the gains of the phototubes and establish the energy calibration of all calorimeter modules before installation into the final detector. A description of the final system to be used in PHENIX, based on a high power YAG laser, is also given.