Detection of Radon by Means of a Proportional Counter

Abstract

The detection of quantities of radon of the order of 10⁻¹² curie by means of a proportional counter is discussed. Two methods are investigated. In one the radon is concentrated in a liquid‐air trap before it is put into the counter and in the other the volume of the counter is made sufficiently large so that the radon can be swept into the counter with a few liters of inert gas. The first method has the advantage of requiring only small counters which work at conveniently low voltages but has low efficiency. The second method has the advantage of simplified filling technique and higher efficiencies, but suffers from the difficulty of obtaining stable operation unless the sweeping and filling gas is helium.