Characterization of large area photomultipliers and its application to dark matter search with noble liquid detectors

Abstract

There is growing interest in the use of noble liquid detectors to study particle properties and search for new phenomena. In particular, they are extremely suitable for performing direct searches for dark matter. In this kind of experiments, the light produced after an interaction within the sensitive volume is usually read-out by photomultipliers. The need to go to masses in the tonne scale to explore deeper regions of the parameter space, calls for the use of large area photomultipliers. In this paper we address the need to perform laboratory calibration measurements of these large photomultipliers, in particular to characterize its behaviour at cryogenic temperatures where no reference from the manufacturer is available. We present comparative tests of phototubes from two companies. The tests are performed in conditions similar to those of operation in a real experiment. Measurements of the most relevant phototube parameters (quantum efficiency, gain, linearity, etc.) both at room and liquid Argon temperatures are reported. The results show that the studied phototubes comply with the stringent requirements posed by current dark matter searches performed with noble-liquid detectors.