Design & Optimization of the HV divider for JUNO 20-inch PMT

TL;DR

This paper details the design and optimization of high-voltage dividers for JUNO's 20-inch PMTs, enhancing performance and reliability for the large-scale neutrino detector.

Contribution

It introduces four HV divider schemes tailored for different scenarios, with the final version adopted by JUNO, and confirms successful production and testing of all PMTs.

Findings

Optimized HV divider designs improve PMT performance.

All PMTs passed production and burning tests.

Final HV divider scheme adopted by JUNO.

Abstract

The Jiangmen Underground Observatory (JUNO) is a 20-kton liquid scintillator detector that employs 20,000 20-inch photomultiplier tubes (PMTs) as photon sensors, with 5,000 dynode-PMTs from HAMAMATSU Photonics K.K. (HPK), and 15,000 MCP-PMTs from North Night Vision Technology (NNVT) installed in pure water. JUNO aims to provide long-lasting and the best performance operation by utilizing a high-transparency liquid scintillator, high detection efficiency PMTs, and specially designed electronics including water-proof potting for the high voltage (HV) dividers of PMTs. In this paper, we present a summary of the design and optimization of HV dividers for both types of 20-inch PMTs, which includes collection efficiency, charge resolution, HV divider current, pulse shape, and maximum amplitude restriction. We have developed and finalized four schemes of the HV divider for different scenarios, including the final version selected by JUNO. All 20,000 20-inch PMTs have successfully undergone production and burning tests.