A COMPACT GAS CHERENKOV DETECTOR WITH NOVEL OPTICS

We discuss the design and performance of a threshold Cherenkov counter for identification of charged hadrons. The radiator is pressurized ga s, which is contained in thin-walled cylindrical modules, A mirror sys tem of novel design transports Cherenkov photons to photomultiplier tu bes, This system is compact, contains relatively little material, and has a large fraction of active volume, A prototype of a module designe d for the proposed CLEO III detector has been studied using cosmic ray s, Results from these studies show good agreement with a detailed Mont e Carlo simulation of the module and indicate that it should achieve s eparation of pions and kaons at the 2.5 sigma-3.0 sigma level in the m omentum range 0.8-2.8 GeV/c. We predict performance for specific physi cs analyses using a GEANT-based simulation package.