The Hyper-Kamiokande detector: R&D studies of a new generation of photosensors

Hyper-Kamiokande is a large water Cherenkov detector which, just like the successful Super-Kamiokande, requires large aperture, high sensitivity photosensors able to detect the weak Cherenkov light generated by neutrino interactions or proton decay. The capability of a water Cherenkov detector largely relies on the performance of its photosensors. Currently the photosensors used in Super-Kamiokande, characterised by the 50 cm diameter photocathode, are the world's largest photomultiplier tubes. The ambitious physics program of Hyper-Kamiokande will be possible only by using a new generation of photosensors whose performances are considerably improved with respect to those currently available. In this paper the current status of development of Hyper-Kamiokande photodetectors will be reviewed.