Study of 144-channel multi-anode hybrid avalanche photo-detector for the Belle RICH counter

Abstract A new hybrid avalanche photo-detector has been developed for the Belle RICH counter. The basic features of this device were examined with and without a magnetic field. By constructing a RICH prototype counter using 6 photo-detectors, we carried out a test beam experiment to confirm the performance. We obtained a single photon Cherenkov angle resolution of 12.8 mrad with 4.6 photo-electrons in our experimental setup, demonstrating that 4 σ π / K separation at 4 GeV/c was achieved.