The CLEO RICH detector

We describe the design, construction and performance of a Ring Imaging Cherenkov Detector (RICH) constructed to identify charged particles in the CLEO experiment. Cherenkov radiation occurs in LiF crystals, both planar and ones with a novel “sawtooth”-shaped exit surface. Photons in the wavelength interval 135-165 nm are detected using multi-wire chambers filled with a mixture of methane gas and triethylamine vapor. Excellent π/K separation is demonstrated.