Velocity and Charge Reconstruction with the Ams/rich Detector

The Alpha Magnetic Spectrometer (AMS), to be installed on the International Space Station (ISS) in 2008, will be equipped with a proximity focusing Ring Imaging Čerenkov detector (RICH). This detector will be equipped with a dual radiator (aerogel+NaF), a lateral conical mirror and a detection plane made of 680 photomultipliers and light-guides, enabling measurements of particle electric charge and velocity. A likelihood method for the Čerenkov angle reconstruction was applied leading to a velocity determination for protons with a resolution around 0.1%. The electric charge reconstruction is based on the counting of the number of photoelectrons and on an overall efficiency estimation on an event-by-event basis. Results from the application of both methods are presented.