Performance of the CLEO IIILiF-TEA ring imaging Cherenkov detector in a high-energy muon beam

The CLEO III Ring Imaging Cherenkov detector uses LiF radiators to generate Cherenkov photons which are then detected by proportional wire chambers us ing a mixture of CH4 and TEA gases. The first two photon detector modules w hich were constructed, were taken to the Fermilab and tested in a beam dump that provided high-momentum muons. We report on results using both plane a nd "sawtooth"-shaped radiators, Specifically, we discuss the number of phot oelectrons observed per ring and the angular resolution. The particle separ ation ability is shown to be sufficient for the physics of CLEO III. (C) 20 00 Elsevier Science B.V. All rights reserved.