The Laser System for the STAR Time Projection Chamber.

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