A Cosmic Ray Test Stand for the PHENIX Muon Trigger RPCs

Resistive Plate Chambers (RPC's) will be used in the first level muon trigger for W events in the PHENIX detector at RHIC. As technology for the upgrade PHENIX has chosen fast CMS muon trigger bakelite RPCs. In order to understand RPC's and to gain experience in operating them, institutions within the PHENIX collaboration have undertaken an intense research effort in which they both develop and test RPC's. In this presentation we will describe the cosmic ray test stand setup at the University of Illinois at Urbana and present some of the results we have obtained. In particular, we shall present results for the efficiency, position resolution, timing resolution, and cluster size for RPC prototypes developed at UIUC.