PARTICLE IDENTIFICATION IN TEC TRD - PROTOTYPES FOR THE PHENIX DETECTOR AT RHIC/

The tracking system in the PHENIX detector at RHIC has been designed t o track charged particles in a high track density environment (dN(c)/d y = 1500), This corresponds to similar to 500 charged particles, prima rily pions, in the fiducial volume of the detector, with a spectrum pe aked at similar to 250 MeV/c. The TEC/TRD subsystem will track all cha rged particles and contribute to the particle identification between 2 00 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 n egatively charged particles at the AGS, An electron-pion separation at levels up to a factor of 200 by dE/dx was measured, This separation f actor was measured as a function of the particle momentum and angle, a nd the gain and gas mixture used in the chamber.