Preparation for mass production and quality assurance of the mPMT module for Hyper-Kamiokande

Hyper-Kamiokande will be the next generation of large-scale water Cherenkov detectors. It aims at obtaining exciting results in many areas, such as the study of CP violation, the search for proton decay and the study of accelerator, atmospheric, solar and astronomical neutrinos. The Hyper-Kamiokande Far Detector will be equipped with a hybrid photosensor configuration combining the 20” photomultiplier tubes (PMT) with the multi-PMT modules, a novel technology first designed for the KM3NeT experiment. The multi-PMT module is based on a pressure vessel instrumented with 19 small diameter (7.7 cm) photosensors, each one with a different orientation. The readout electronics and high-voltage power supplies for the photomultiplier tubes are also integrated within the module. It offers several advantages such as increased granularity, reduced dark rate, weaker sensitivity to the Earth’s magnetic field, improved time resolution and directional information with an almost isotropic field of view. The R&D of the mPMT prototype is almost complete and now preparations for mass production are now underway. In this contribution the results of the tests performed on the first prototypes as well as the procedures for quality assurance and Hyper-Kamiokande’s multi-PMT program are discussed.