Photomultiplier cooling apparatus

Abstract

A simple cooler is described which enables a photomultiplier to be maintained at a controlled temperature in the vicinity of -20°C. It is noted that several workers have observed that the thermionic component of the dark current becomes negligible after cooling below about -20°C whilst the risk of damage to the tube is progressively increased. It is therefore considered that a tube temperature of this order is the optimum and the design of a photomultiplier housing and simple temperature control circuit for photomultiplier stabilization at this temperature are described. After approximately 30 minutes stabilization time the tube temperature deviations are observed to be within ±0.25 degC.