The design and operation of a fast 2π gas-flow counter for alpha particles

The accurate measurement of high emission rates of alpha radioactive sources has been neglected up to the present time. In order to resolve this difficulty a new 2π proportional counter was developed, capable of measurement up to at least 5×10⁵ alpha particles per second into 2π geometry. Careful attention was placed on the factors limiting counting speed, notably mechanical and electrical design of the counter and preamplifier circuitry. The choice of counting gas was also critical for high speed applications. The calibration of the counter was checked using a certified standard source from the Radiochemical Centre emitting 1·029×10⁵ alpha particles per minute. The measured emission rate of the source agreed to within ±0·1% of this figure.