The STAR Experiment at RHIC

Abstract

STAR (Solenoid Tracker at RHIC) will be one of two large, sophisticated experiments ready to take data when the Relativistic Heavy Ion Collider (RHIC) comes on-line in Fall of 1999. The design of STAR, its construction and commissioning and the physics program using the detector are the responsibility of a collaboration of over 350 members from 34 institutions, world-wide. The overall approach of the STAR collaboration to the challenge of studying collisions of highly relativistic nuclei is to focus on measurements of the properties of the many hadrons produced in individual events. The STAR detector is optimized to detect and identify hadrons over a large solid angle so that individual events can be characterized, in detail, based on their hadronic content. The broad capabilities of the STAR detector will permit an examination of a wide variety of proposed signatures for the Quark Gluon Plasma (QGP) on an eventby-event basis, using a sample of events which come from collisions resulting in a large energy density deposited in the central region In order to achieve this goal, the STAR experiment is based on a solenoid geometry with tracking detectors using the time projection chamber¹ (TPC) approach and covering a large range of pseudo-rapidity so that individual tracks can be seen within the very high track density expected in central collisions at RHIC. A Silicon Vertex Tracker (SVT) is sensitive to charged tracks above 40 MeV/c transverse momentum while additional TPCs provide tracking in the forward cones. STAR also utilizes particle identification by the dE/dx technique in the TPC and SVT and by time-of-flight. Electromagnetic energy is detected in a large solid angle calorimeter. The construction of STAR, which will be located in the Wide Angle Hall at the 6 o’clock position at RHIC, formally began in early 1993. The so-called “baseline scope” consisting of the TPC and its readout electronics, the 0.5 T solenoid magnet, data acquisition, trigger, software and support infrastructure is proceeding towards completion in 1999 in time for the first RHIC physics run. The SVT, partial implementation of the electromagnetic calorimeter and the forwards TPCs will be available soon thereafter with full implementation of the detector occurring as funding permits.