Performance test and qualification of the photomultiplier tube for the whole production of LHAASO-ED

Abstract

Over 5000 1.5-inch photomultiplier tubes (PMTs) are deployed in the electromagnetic particle detectors (EDs) of the Large High Altitude Air Shower Observatory (LHAASO). The PMTs are developed as two outputs devices (the anode and the 6th dynode) to measure the large dynamic ranges of particle densities within the extensive air shower. Before assembly, the PMTs must be fully tested to ensure the products meet the performance requirements. A dedicated test bench has been designed for this purpose, capable of testing multiple PMTs simultaneously. The major performances such as single photoelectron spectrum, gain versus high voltage, pulse linearity, dark noise rate and temperature coefficient are measured for each PMT, and transit time spread (TTS) is measured from a 5% sample. The PMTs that comply with the requirements are used in the EDs construction. The design of the PMT voltage divider and the test results of 5366 PMTs are presented in this paper.