Y. Yokota

PHENIX central arm particle ID detectors

Abstract The Ring-Imaging Cherenkov (RICH) and the Time-of-Flight (ToF) systems provide identification of charged particles for the PHENIX central arm. The RICH is located between the inner and outer tracking units and is one of the primary devices for identifying electrons among the very large number of charged pions. The ToF is used to identify hadrons and is located between the most outer pad chamber (PC3) and the electromagnetic calorimeter. A Time Zero (T0) counter that enhances charged particle measurements in p–p collisions is described. Details of the construction and performance of both the RICH, ToF and T0 are given along with typical results from the first PHENIX data taking run.

A large-acceptance spectrometer for tracking in a high-multiplicity environment, based on space point measurements and high-resolution time-of-flight

A large acceptance tracking system, specially developed for tracking at very high particle densities encountered in ultra-relativistic heavy-ion collisions is described. The system is a combination of multi-step avalanche chambers equipped with electronic pad readout with high position resolution in two dimensions and streamer-tube detectors with pad readout, with coarser position resolution, that is sufficient for safe pattern recognition. A high-resolution time-of-flight system (time resolution better than 90 ps) provides particle identification up to 8 GeV/c for pions and protons and pion/kaon separation up to 4 GeV/c. All detectors in the tracking system are read out with new, high-performance integrated circuits. The system can operate at high event rates due to efficient zero suppression. The performance of the system for tracking under real running conditions with Pb-beam at 158 A GeV in the WA98 experiment at CERN is presented

A gas Cherenkov beam counter with a timing resolution of 30 ps for relativistic heavy ion experiments

Abstract We constructed gas a Cherenkov beam counter for a lead beam to obtain start signals of time of fight measurements for relativistic heavy ion experiments in WA98 at CERN-SPS. The intrinsic timing resolution of the gas Cherenkov counter was found to be ≤ 30 ps at a beam intensity up to 3 × 10 5 ions/s and the charge resolution ( ΔZ Z ) was 2.0% for lead ions of 160 GeV/ c per nucleon. This counter has been successfully operated for more than 1 1 2 month of heavy ion run in 1995.