Particle identification in TEC/TRD prototypes of the PHENIX detector at RIHC

The tracking system in the PHENIX detector at RHIC has been designed to track charged particles in a high track density environment (dNc/dy=1500). This corresponds to ∼500 charged particles, primarily pions, in the fiducial volume of the detector, with a spectrum peaked at ∼250 MeV/c. The TEC/TRD subsystem will track all charged particles and contribute to the particle identification between 200 MeV/c and 2.5 GeV/c by performing fine sampling energy loss (dE/dx) measurements. Prototype chambers were tested in a secondary beam of negatively charged particles at the AGS. An electron-pion separation at levels up to a factor pf 200 by dE/dx was measured. This separation factor was measured as a function of the particle momentum and angle, and the gain and gas mixture used in the chamber. (orig.)