There is considerable theoretical evidence to support the idea that when ordinary nuclear matter is heated or compressed to extraordinary temperatures and pressures, the protons and neutrons which make up atomic nuclei will melt into their constituent quarks and gluons. The nuclear matter thus undergoes a phase transition to the quark-gluon plasma, or QGP. The universe is postulated to have existed in this deconfined phase of matter for the first few microseconds after the Big Bang. We believe it is possible to recreate this phase transition in the laboratory by colliding heavy ions at ultra-relativistic energies. The search for the nuclear phase transition is so compelling that the Nuclear Science Advisory Committee has designated the Relativistic Heavy Ion Collider (RHIC), now under construction at Brookhaven National Laboratory, as the highest priority in nuclear physics for the United States. And in 1996 the European science community approved the construction of the Large Hadron Collider (LHC) which will turn on six years after RHIC in 2005. The Vanderbilt experimental relativistic heavy ion group is actively participating in this exciting new branch of nuclear science. We are members of E864/E941, now at the Brookhaven Alternating Gradient Synchrotron (AGS), and the PHENIX detector collaboration which is the largest of the experiments funded for RHIC.
 
 

While RHIC represents the future of relativistic heavy ion physics, the fixed target program at the Brookhaven Alternating Gradient Synchrotron (AGS) is the source of considerable experimental activity today. The AGS accelerates ions as heavy as gold, up to energies of 11.7 Gev/c per nucleon and allows us to study systems with very high baryon densities. We are working in collaboration with several other institutions on Experiment 864, a high sensitivity search for multi-strange, multi-quark systems which may be produced during relativistic heavy ion collisions.

The collisions between heavy ions at high energies, such as are produced at the Brookhaven AGS, are a likely place to search for the production of strange quark matter. A typical central collision between gold nuclei produces 15-20L's, so the system after collision possesses a high degree of strangeness. One production scenario is that the particles after collision are close in both momentum and configuration space, and that the strange matter simply coalesces from the collision debris. The second, more exciting possibility is that strange matter is formed as the result of a distillation process that takes place during the hadronization of a quark-gluon plasma.
Detection of such strange matter has been proposed as a possible signature for quark-gluon plasma.

To achieve this goal, the collaboration has built a spectrometer with a high rate capability, a large acceptance, and excellent resolution. In addition to the search for strange matter, these properties make the spectrometer ideal for several measurements relevant to the study of matter in the extreme conditions of temperature and density achieved during collisions of heavy ions at the AGS. Such measurements include the study of antimatter production in order to probe the baryon density of the system after collision, and measurements of light nuclei formed during the collisions, which allow us to test various dynamical collision models of heavy ion reactions.
 
 

The PHENIX (pioneering-high-energy-nuclear interactions-experiment) detector collaboration is a broad-based international group of nearly 400 scientists, engineers, and graduate students from some 50 institutions in a dozen different countries. The detector itself consists of ten different subsystems and the Vanderbilt group is charged with the supervision of the integrated detector simulation. As well as the assembly and fabrication of the pad chambers (PC-3 & PC2).  This effort is now well into its tenth year and will continue to be active during detector commissioning and data acquisition in year 2000.

The primary goal of the PHENIX experiment is to detect the QGP and to measure its properties. There are many potential signatures of the QGP, especially the so-called "hard probes" such as dilepton pairs and the thermal radiation of the plasma itself as manifested in the photon spectrum. The great advantage of PHENIX is that these special signatures are all measured in the same apparatus and can be correlated a function of a single variable such as the measured transverse energy density. In addition to measuring continuum spectra, PHENIX is also admirably designed to observe discrete resonances such as the , the J/S family, and the family.  In particular, theVanderbilt group is especially interested in (2S) suppression signals for the QGP as detected by the Muon subsystem in PHENIX.

The Pad Chamber is one of the Subsystems in the PHENIX tracking System. It is composed of three layers of pixel detectors. PC-1 is
located directly outside of the Drift Chamber, DC. PC-2 is located immediately in front of the Time Expansion Chamber, TEC. PC-3 isimmediately in back of the TEC.
 
 

last updated by Darryl Borland 02.04.00