The development of a hybrid photo-detector (HPD) for the Hyper-Kamiokande project

We are developing hybrid photo-detectors (HPDs) for Hyper-Kamiokande, which is a next generation underground water Cherenkov detector designed to search for proton decay and study many topics related to neutrino physics and astrophysics. A verification study of the suitability of HPDs for a water Cherenkov detector in a 200-ton tank is planned. In advance, we evaluated the performances of an 8-in. prototype HPD and tested them in water to confirm their safe operation. The prototype shows better single photon sensitivity and timing resolution than the conventional PMTs used in Super-Kamiokande.