Testbeam results on particle identification with aerogel used as RICH radiator

Abstract We present the results obtained by testing in a beam sample of silica aerogel which is foreseen as one of the radiators for the Ring Imaging Cherenkov counter of LHCb. Pion and proton beams with momenta ranging from 6 to 10 GeV/ c traversed different thickness of aerogel. Two large diameter (12 cm) Hybrid Photodiodes with 2048 channels, produced at CERN, were used as photodetectors. The number of photoelectrons and the radius of the Cherenkov rings allowed pion–proton separation over the whole considered momentum range.