B. R. Schlei

Hydrodynamical analysis of single inclusive spectra and Bose-Einstein correlations for Pb + Pb at 160 AGeV☆

Abstract We present the first analysis of preliminary data for Pb + Pb at 160 AGeV using 3 + 1-dimensional relativistic hydrodynamics. We find excellent agreement with the rapidity spectra of negative hadrons and protons and the correlation measurements. The data indicate a large amount of stopping; 65% of the invariant energy of the collision is thermalized and 73% of the baryons are contained in the central fireball. Within our model this implies that a quark-gluon-plasma of lifetime 3.4 fm/ c was formed.

The linear correlation coefficient vs. the cross term in Bose-Einstein correlations

Abstract We investigate the nature of the new cross term for Gaussian parameterizations of Bose-Einstein correlations of identical particles emitted from purely chaotic hadron sources formed by relativistic heavy ion collisions. We find that this additional parameter in the so-called Bertsch-Pratt parameterization can be expressed in terms of a linear “out-longitudinal” correlation coefficient for emission of bosons and two already known “radius” parameters, R l and R o . The linear correlation coefficient is of kinematical origin and can be used to determine the widths of longitudinal momentum distributions.

High density interconnect multi-chip module for the front-end electronics of the PHENIX/MVD

A multi-chip module (MCM) based on High Density Interconnect (HDI) technology was developed for the front-end electronics of a high energy nuclear physics experiment to process charge pulses from silicon detectors. Stringent requirements in performance as well as low radiation length and minimum physical size of the module dictated the use of the most sophisticated MCM technology available. The module handles 256 input channels on an alumina substrate with milled cavities for die placements and four layers of thin-film traces of 42u width. A total of 20 custom integrated circuit chips and 98 passive components are assembled on a substrate of size 43 mm/spl times/48 mm. Various aspects of development efforts for the design and fabrication as well as the electrical test results of the module are discussed.

π−π+ ratio in heavy ion collisions: Coulomb effect or chemical equilibration?☆

Abstract We calculate the π − π + ratio for Pb + Pb at CERN/SPS energies and for Au + Au at BNL/AGS energies using a (3+1) dimensional hydrodynamical model. Without consideration of Coulomb effect an enhancement of this ratio at low m t is found compatible with that observed in these experiments. Our calculations are based on previous (3+1) dimensional hydrodynamical simulations (HYLANDER), which described many other aspects of experimental data. In this model the observed enhancement is a consequence of baryon and strangeness conservation and of chemical equilibration of the system and is caused by the decay of produced hyperons, which leads to a difference in the total number of positive and negative pions as well. Based on the same approach, we also present results for the π − π + ratio for S + S (CERN/SPS) collisions, where we find a similar effect. The absence of the enhancement of the π − π + ratio in the S + S data presented by the NA44 Collaboration, if confirmed, could indicate that chemical equilibration has not yet been established in this reaction.

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).

Observables in relativistic heavy-ion collisions

This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). We used several complimentary models of high-energy nuclear collisions to systematically study the large body of available data from high energy (ph,,,/A > 10 GeV/c) heavy ion experiments at BNL and CERN and to prepare for the data that will come from RHIC. One major goal of this project was to better understand the space-time history of the excited hadronic matter formed in these collisions and to use this understanding to improve models of this process. The space-time structure of the system can be extracted from measurements of single-particle pT distributions and multiparticle correlations. We looked for experimental effects of the formation of the quark-gluon plasma. Understanding the hadronic phase of the interaction determines the sensitivity of experimental measurements to the presence of this exotic state of matter. Background and Research Objectives The theory of strong interactions -quantum chromodynamics --predicts the existence of a state of matter in which quarks and gluons are no longer confined within hadrons. Hadrons are the ordinary strongly interacting particles that are made from either two or three quarks each. Examples are protons, neutrons, pions and kaons. This state, called the Quark-Gluon Plasma (QGP), is expected to be produced when hadronic matter is excited to sufficiently high energy density. The QGP is believed to have existed for the first 10 micro-seconds or so of cosmological time and possibly still does exist in the center of neutron stars. Ongoing experiments at the BNL (Brookhaven National Lab) AGS (Alternating Gradient Synchrotron) and the CERN (European Particle Physics Laboratory) SPS (Super Proton Synchrotron) accelerators are attempting to produce and study the QGP in the laboratory; further experiments will be carried out at the Relativistic Heavy Ion Collider (RHIC), which is now under construction at BNL. As in the early history of the universe, systems produced in the laboratory expand and cool and the QGP, if produced, undergoes a phase transition to a hot dense system of hadrons, which continues to expand until the particles stop interacting (freeze-out). The * Principal Investigator, e-mail: sullivan@lanl.gov