On the reconstruction of Cherenkov rings from aerogel radiators

An event reconstruction algorithm to analyze Cherenkov rings in a Ring Imaging Cherenkov (RICH) detector is considered and the results of a Monte Carlo simulation are discussed. It is demonstrated that aerogel radiators can be used in RICH detectors despite the Rayleigh scattering of light if filtered by a pattern recognition program. The velocity of the particle radiating Cherenkov light, β, is determined by a fit to the photon hit pattern, assuming prior momentum measurement by a tracking system. The charge of the particle, z, is obtained from the collected light. The results show that, for the geometries considered, velocity resolutions σβ/β≃1×10−3 and charge resolutions σZ/Z≃10% can be achieved for 5 GeV/c protons and a 2 cm thick aerogel radiator.