Silicon photomultiplier as a detector of Cherenkov photons

A novel photon detector - i.e. the silicon photomultiplier- whose main advantage over conventional photomultiplier tubes is the operation in high magnetic fields, has been tested as a photon detector in the proximity focusing RICH with aerogel radiator. This type of RICH counter is proposed for the future upgrade of the Belle detector at the KEK B-factory. Recently produced silicon photomultipliers show less noise and have larger size, which are the major issues for a large area photon detector. The results of measurements of single photo- electron pulse height distributions , timing resolution and position sensitivity for different silicon photomultipliers (Hamamatsu MPPC HC025, HC050, and HC100) are presented. The silicon photomultipliers were then used to register Cherenkov photons emitted by cosmic ray particles in the proximity focusing aerogel RICH. Various light guides were investigated in order to increase the detection efficiency.