Mechanical design of multi-PMTs for IWCD

Abstract

Approximately 500 multi-PMTs (mPMTs) will be used as the photosensors for the Intermediate Water Cherenkov Detector (IWCD), a new near detector for the approved Hyper-Kamiokande experiment that will be built by 2025. The IWCD mPMT design has nineteen 3” PMTs enclosed in a water-tight pressure vessel, along with the associated electronics. The 3” PMTs provide excellent spatial imaging of the neutrino-induced Cherenkov light ring. This work will focus on the mechanical design of the mPMT vessel. In particular, design of the acrylic dome, use of optical gel to couple the dome to the PMTs, assembly procedures of dome and PMT sub-assembly (including the necessary jigs / fixtures), design of water-tight feed-through & plans for testing and results from several mPMT prototypes.