PUB - Publikationen an der Universität Bielefeld

COMPASS RICH-1, designed in 1996 for hadron identification at high momenta in the COMPASS large angle spectrometer, is a large acceptance gaseous RICH with a 3 m thick C4F10 radiator. MWPCs with CsI photocathodes are used as VUV photon detectors and the image focalization is provided by a large UV mirror wall. pi/K are separated in the several 10 GeV/c domain. The main characteristics of the detector are the large acceptance resulting in very large transversal dimensions, the use of far UV photon detectors, which implies VUV transparency of the radiator gas and good VUV mirror reflectance and the high rate capabilities, made possible by the read-out system architecture. The detector description, the various technological achievements and present performances are given. In particular, preliminary RICH-1 performances obtained analysing the data from the 2002 and 2003 runs are presented. (C) 2004 Published by Elsevier B.V.