A proximity focusing RICH detector for Kaon Physics in Hall A at Jefferson Lab 

F. Garibaldi

Hall A RICH collaboration

     Important information on the Lambda - N interaction are expected from the High Resolution Hypenuclear Spectroscopy experiment with electron probes to be performed in Hall A at Jefferson Lab at the end of 2002. Unambiguous Kaon identification is needed for this kind of experiment. The signal is expected to be small compared to the very high pion and proton backgrounds due to the small electron and Kaon detection angles. The "standard" Hall A PID apparatus (TOP and 2 aerogel threshold Cherenkov detectors) does not provide sufficient suppression of the background. Simulations and calculations have shown that a RICH detector would solve the problem. A proximity focusing freon/CsI detector has been designed, built, tested and commissioned-Simulation results, design criteria and performances obtained with cosmics and in-beam tests both at CERN PS and Jefferson Lab will be presented.