Characterization of the 20-inch Photomultiplier Tubes for RENE Detector

TL;DR

This paper characterizes 20-inch Hamamatsu R12860 photomultiplier tubes, analyzing their charge, timing, and pulse responses to support the RENE neutrino detector and similar experiments.

Contribution

It provides detailed measurements of gain uniformity, pulse timing, and afterpulse characteristics of the R12860 PMTs for the first time.

Findings

Maximum gain variation due to large photocathode structure

Detailed timing and charge distribution of late pulses and afterpulses

Data aiding systematic uncertainty estimation in neutrino detection

Abstract

To address the Reactor Antineutrino Anomaly (RAA) observed in neutrino experiments, the Reactor Experiment for Neutrino and Exotics (RENE) has been initiated using a liquid scintillation detector. In this study, we investigate the characteristics of two 20-inch Hamamatsu R12860 photomultiplier tubes (PMTs) intended for installation in the RENE detector. The charge and timing responses of the PMTs were evaluated at both the nominal and target gains expected during actual operation. In particular, gain non-uniformity arising from the large-diameter photocathode with a box-and-line type dynode structure was examined, and the maximum gain variation was measured. The occurrence rate, timing, and charge distributions of late pulses and afterpulses were also investigated to characterize the specific response features of the R12860 PMT. The results reported in this study will aid in the interpretation of signals from the RENE detector and serve as a reference for estimating potential systematic uncertainties in RENE data. Furthermore, these findings are expected to provide valuable information for other experiments employing the same type of PMTs.