A Gas RICH for Cosmic Ray Studies

A newly developed gas Ring Imaging Cherenkov (RICH) detector for cosmic ray studies was used in the WiZard/CAPRICE98 balloon-borne experiment. The performance of the gas-RICH will be presented. The detector was built for identifying charge one particles and specifically antiprotons and positrons in a large background of cosmic ray particles. This is the first time cosmic ray antiprotons above 18 GeV can be mass resolved on an event by event basis.