Simulation of LHCb RICH detectors using GEANT4

LHCb is one of the experiments at the Large Hadron Collider at CERN. It aims to make precision measurements of CP violation in the B-meson decays. The detector simulation of LHCb was developed using the GEANT4 software toolkit interfaced to the LHCb software framework named GAUDI. This is now being used for a large production run of 210 million events. An important feature of the LHCb experiment is the use of ring imaging Cherenkov counters (RICH) for particle identification. The Cherenkov photons created in this detector are focused onto an array of photodetectors made of Hybrid Photodiodes. A brief overview of the GEANT4 based LHCb simulation program named GAUSS will be given with the main emphasis on RICH simulation and its verification.