A prototype for the AMS-RICH experiment

The AMS spectrometer will be installed at the International Space Station in 2005. Among other improvements over the first version of the instrument, a ring imaging Cherenkov detector will be added and should open a new window for cosmic-ray physics, allowing isotope separation up to A≈25 between 1 and 10 GeV/c and element identification up to Z≈25 between threshold and 1 TeV/c/nucleon. It should also contribute to the high level of redundancy required for AMS and reject efficiency albedo particles. A second generation prototype has been operated for a few months: the architecture and the first results are presented.