A Ludlum, Model 43-5, alpha-survey detector using a zinc-sulphide scintillation crystal doped with silver as the main detector. The crystal is coupled to a 3.8 cm diameter (nominal 1.5 inch) magnetically-shielded photomultiplier tube. The probe has an overall length of 37 cm and the probe has an active area of 76 square cm. The detector window is made of aluminized polyester which is opaque to light, yet thin enough to admit alpha particles. This instrument was used by the Radiation and Industrial Safety (RIS) group at Chalk River.
