Production line and quality assurance of mPMT photosensors for WCTE

The Water Cherenkov Test Experiment (WCTE) at CERN aims to test technologies related to water Cherenkov detectors. The experiment will use 100 multi-PMT photosensors in a 41-ton water tank. These sensors, each comprising nineteen 3” PMTs, are similar to those that will be used in the Hyper-Kamiokande experiment. The production process involves electronics and mechanics assembly, including application of an optical gel. Rigorous quality assurance was implemented to ensure reliability for long-term data collection. WCTE assembly at CERN has already begun, with data collection expected to start in October 2024.