THEORY OF RING IMAGING CHERENKOV COUNTERS

A short review of Cherenkov radiation and its use for particle identification with threshold and differential counters is presented. The focusing principles of Ring Imaging Cherenkov (RICH) counters are then developed and applied successively to gas and liquid radiators. An analysis of proximity focused images from liquid or solid radiators follows. A method to reconstruct the Cherenkov angle from the experimental data is developed for spherical as well as for flat detector surfaces. These formulas define the Cherenkov angle sensitivity due to intrinsic as well as extrinsic (measurement) errors. Particle identification limits are then given for each of the different imaging methods.