Particle identification in LHCb

A brief description of the particle identification system (RICH) of the LHCb experiment is given. Preliminary results are given on a test of the solid radiator, the aerogel. The radiation hardness has been tested with gamma 's and protons. The photoelectron yield, the Cherenkov angle resolution, and pi /p separation were determined with a pi /sup -/ and a mixed pi /sup +//proton beam of momentum between 3 and 10 GeV/c. Four large hybrid photodiodes tubes were used as photodetectors. (5 refs).