A Portable Scintillation Alpha Survey Instrument

A scintillation alpha counter utilizing a zinc sulfide fluor, a multiplier phototube, and a two-stage vacuum tube amplifier has been developed. A neon-bulb oscillator high-voltage supply is used to supply 900 volts to the multiplier phototube, and headphones are used to obtain an aural indication of counting. The average geometry or counting efficiency over the 7.43-inch2 probe area is approximately 13 per cent with variations from a maximum counting efficiency at probe center of 18 to 22 per cent down to approximately 7 to 8 per cent at the probe edges. The background counting rate is less than one count per minute, and the battery life is approximately 150 hours of continuous operation for the 3-1/2 pound instrument.