Calibration of Photomultiplier Arrays

TL;DR

This paper presents a calibration method for photomultiplier arrays that uses science data directly, avoiding dedicated calibration sets and ensuring conditions match between calibration and science data, especially useful in low-background experiments.

Contribution

The method enables calibration without prior knowledge of the single photoelectron response and matches conditions between calibration and science data, improving accuracy in sensitive experiments.

Findings

Calibration method works without external light sources.

Conditions are matched between calibration and science data.

Applicable to low-background experiments like ZEPLIN-III.

Abstract

A method is described that allows calibration and assessment of the linearity of response of an array of photomultiplier tubes. The method does not require knowledge of the photomultiplier single photoelectron response model and uses science data directly, thus eliminating the need for dedicated data sets. In this manner all photomultiplier working conditions (e.g. temperature, external fields, etc) are exactly matched between calibration and science acquisitions. This is of particular importance in low background experiments such as ZEPLIN-III, where methods involving the use of external light sources for calibration are severely constrained.