The STAR Time Projection Chamber (TPC) is used to record collisions at the Relativistic Heavy Ion Collider (RHIC). The TPC is the central element in a suite of detectors that surrounds the interaction vertex. The TPC provides complete coverage around the beam-line, and provides complete tracking for charged particles within ± 1.8 units of pseudo-rapidity of the center-of-mass frame. Charged particles with momenta greater than 100 MeV/c are Preprint submitted to Elsevier Science 5 February 2008 recorded. Multiplicities in excess of 3,000 tracks per event are routinely reconstructed in the software. The TPC measures 4 m in diameter by 4.2 m long, making it the largest TPC in the world.

The Time Projection Chamber (TPC) is the core tracking detector for the STAR experiment at RHIC. To determine spatial distortions, calibrate and monitor the TPC, a laser calibration system has been built. We developed a novel design to produce ~500 thin laser beams simulating straight particle tracks in the TPC volume. The new approach is significantly simpler than the traditional ones, and provides a higher TPC coverage at a reduced cost. During RHIC 2000 and 2001 runs the laser system was used to monitor the TPC performance and measure drift velocity with ~0.02 % accuracy. Additional runs were recorded with and without magnetic field to check ExB corrections.