Particle identification in TEC/TRD Prototypes for the PHENIX detector at RHIC

The tracking system in the PHENIX detector at RHIC has been designed to track charged particles in a high track density environment (dNcdy = 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 MeV/c by performing fine sampling energy loss (dEdx) 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 of 200 by dEdx 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.