PMm2: large photomultipliers and innovative electronics for the next-generation neutrino experiments

TL;DR

This paper introduces a new large-scale photodetection system using segmented macro pixels of 16 photomultiplier tubes with autonomous electronics, designed for next-generation neutrino experiments in large water tanks.

Contribution

It presents a novel architecture with macro pixel segmentation, triggerless data acquisition, and a prototype of electronics validated with 16 PMTs, enhancing scalability and cost-effectiveness.

Findings

Successful testing of front-end electronics with 16 PMTs

Simulation and measurement define PMT and electronics requirements

Development of a pressure-optimized PMT package for underwater use

Abstract

The next generation of proton decay and neutrino experiments, the post-SuperKamiokande detectors as those that will take place in megaton size water tanks, will require very large surfaces of photodetection and a large volume of data. Even with large hemispherical photomultiplier tubes, the expected number of channels should reach hundreds of thousands. A funded R&D program to implement a solution is presented here. The very large surface of photodetection is segmented in macro pixels made of 16 hemispherical (12 inches) photomultiplier tubes connected to an autonomous front-end which works on a triggerless data acquisition mode. The expected data transmission rate is 5 Mb/s per cable, which can be achieved with existing techniques. This architecture allows to reduce considerably the cost and facilitate the industrialization. This document presents the simulations and measurements which define the requirements for the photomultipliers and the electronics. A proto-type of front-end electronics was successfully tested with 16 photomultiplier tubes supplied by a single high voltage, validating the built-in gain adjustment and the calibration principle. The first tests and calculations on the photomultiplier glass led to the study of a new package optimized for a 10 bar pressure in order to sustain the high underwater pressure.