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A simple battery-operated survey instrument has been developed which uses a photo-multiplier tube to detect the scintillations produced in a phosphor by α-particles. The electrical components are a 1100-volt battery pack; a 931A photo-multiplier tube; a matching transformer and headphones for registering single particles; and a crystal rectifier, choke, and meter for use with strong sources. The latter group of components are used in a novel ``charge-multiplying'' circuit which increases the meter sensitivity by a factor of 12. The instrument is insensitive to β- and γ-radiations.
R. Sherr (1947) studied this question.