M. J. Bennett

PHENIX inner detectors

Abstract The timing, location and particle multiplicity of a PHENIX collision are determined by the Beam–Beam Counters (BBC), the Multiplicity/Vertex Detector (MVD) and the Zero-Degree Calorimeters (ZDC). The BBCs provide both the time of interaction and position of a collision from the flight time of prompt particles. The MVD provides a measure of event particle multiplicity, collision vertex position and fluctuations in charged particle distributions. The ZDCs provide information on the most grazing collisions. A Normalization Trigger Counter (NTC) is used to obtain absolute cross-section measurements for p–p collisions. The BBC, MVD and NTC are described below.

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.

E1 transition probabilities between the nilsson states 12+[411] and 12− [541]

Abstract The half-lives of the 1 2 , 1 2 + [411] level at 208.1 keV in 171Lu and of the 1 2 , 1 2 + [411] and 3 2 , 1 2 + [411] levels at 425.0 and 434.6 keV in 173Lu have been measured in the decay of 171Hf and 173Hf to be 29.7±1.1 ns, 0.82±0.20 ns and 0.46±0.20 ns, respectively. These half-lives yield the absolute γ-ray transition probabilities of the El transition from 1 2 , 1 2 + [411] to 1 2 , 1 2 − [541] in 171Lu and of the E1 transitions from 1 2 , 1 2 + [411] to the spin 1 2 and 1 2 members of the 1 2 − [541] band and from 3 2 , 1 2 + [411] to the spin 3 2 and 5 2 members of the 1 2 − [541] band in 173Lu. These absolute transition probabilities are found to be in good agreement with the Nilsson estimate, taking into account pairing correlations and Coriolis coupling.

Initial state energy loss dependence of J/Ψ and Drell–Yan in relativistic heavy ion collisions

Abstract We present a Glauber-based study of J/Ψ and Drell–Yan yields in nucleus–nucleus collisions. Using this approach, we have investigated the impact of energy loss by the colliding nuclei on observed yields and transverse momentum spectra of J/Ψ and Drell–Yan. These studies permit an assessment of the importance of initial state energy loss in relation to “anomalous” J/Ψ suppression.

Geometric parametrization of J/{psi} absorption in heavy ion collisions

We calculate the survival probability of J/{psi} particles in various colliding systems using a Glauber model. An analysis of recent data has reported a J/{psi}-nucleon breakup cross section of 6.2{plus_minus}0.7 mb derived from an exponential fit to the ratio of J/{psi} to Drell-Yan yields as a function of a simple, linearly averaged mean path length {l_angle}L{r_angle} through the nuclear medium. Our calculations indicate that, due to the nature of the calculation, this approach yields an apparent breakup cross section which is systematically lower than the actual value. {copyright} {ital 1999} {ital The American Physical Society}

The PHENIX Multiplicity and Vertex Detector

Abstract We describe the design and expected performance of the PHENIX Multiplicity and Vertex Detector (MVD) sub-system of the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC).

Simulations of the performance of the MVD in PHENIX

The PHENIX Multiplicity Vertex Detector (MVD) provides event characterization, a centrality trigger, collision vertex position, and measures fluctuations in charged particle multiplicities. The design criteria include a large rapidity coverage, good azimuthal coverage and granularity, minimizing material in the electron arm acceptance, and minimizing costs. The MVD contains two concentric barrels of Si strip detectors with two disk-shaped Si pad detector endcaps. Simulations show that the vertex position can be located to within a few hundred microns using hits in the barrels. A channel multiplicity signal is formed for use in the Level-1 trigger. The effect of the expected discriminator performance on this trigger signal will be shown. The pad and strip detectors are read-out with identical electronics. The influence of the performance of the electronics on the detectors performance are discussed.