Mass production and characterization of 3-inch PMTs for the JUNO experiment

TL;DR

This paper reports on the mass production and detailed characterization of 26,000 3-inch photomultiplier tubes for the JUNO neutrino experiment, marking the largest such sample studied to date.

Contribution

It presents the first large-scale production and comprehensive performance analysis of 3-inch PMTs for a major neutrino experiment.

Findings

High production success rate with only 15 rejected tubes

Concurrent factory characterization of 15 performance parameters

Implementation of novel strategies to enhance quality assurance

Abstract

26,000 3-inch photomultiplier tubes (PMTs) have been produced for Jiangmen Underground Neutrino Observatory (JUNO) by the Hainan Zhanchuang Photonics Technology Co., Ltd (HZC) company in China and passed all acceptance tests with only 15 tubes rejected. The mass production began in 2018 and elapsed for about 2 years at a rate of $\sim$1,000~PMTs per month. The characterization of the PMTs was performed in the factory concurrently with production as a joint effort between HZC and JUNO. Fifteen performance parameters were tracked at different sampling rates, and novel working strategies were implemented to improve quality assurance. This constitutes the largest sample of 3-inch PMTs ever produced and studied in detail to date.