Measurement of the relative Quantum Efficiency of Hamamatsu model R5912-20MOD photomultiplier tubes at liquid argon temperature

TL;DR

This paper measures the quantum efficiency of Hamamatsu R5912-20MOD photomultiplier tubes at liquid argon temperature, revealing wavelength-dependent changes crucial for cryogenic detector applications.

Contribution

It introduces a new test setup and provides the first detailed measurement of QE variation of this PMT model at cryogenic temperatures.

Findings

QE changes within 5% at 420 nm from room to cryogenic temperature

QE increases by about 10% at shorter wavelengths at LAr temperature

QE decreases significantly after 550 nm at LAr temperature

Abstract

The model R5912-20MOD photomultiplier tube(PMT) is made for cryogenic application by Hamamatsu. In this paper, we report on the measurement of relative quantum efficiency (QE) of this model PMT at liquid argon(LAr) temperature. Furthermore, a specially designed setup and relevant test method are introduced. The relative QE is measured in visible wavelengths with the PMT emerged in high purity nitrogen atmosphere. The results show that the change of QE at LAr temperature is within about 5% compared with room temperature around 420 nm. However, the QE increases about 10% in the shorter wavelength range and decreases significantly after 550 nm.