  The AMS spectrometer will be installed on the International Space Station in
2005. Among other improvements over the first version of the instrument, a ring
imaging Cherenkov detector (RICH) 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.
