Measurement of Cherenkov photons by SiPMs with light guides

Silicon Photomultipliers (SiPMs) are attractive photon detectors for Ring Imaging Cherenkov (RICH) counters inside large magnetic spectrometers due to their insensitivity to magnetic fields. We have investigated the possibilities offered by these new photon detectors in a cosmic ray test set-up. Cherenkov photons emitted by cosmic ray particles in an aerogel radiator have been detected with silicon photomultipliers for the first time. Estimates and tests show how light concentrators may improve the detection efficiency, thus showing promise for a SiPM based RICH detector. The optimum shape for these light guides is investigated.