Determination of radon-222 in gases by alpha counting of its decay products deposited on the inside walls of a proportional counter

Abstract A new method for the determination of radon-222 in gases has been developed. A proportional counter is filled with a gas containing radon and is left for about 1 hour. During this time the decay products of radon will be deposited on the walls of the counter. The gas is then evacuated and replaced with a mixture of argon and methane. The alpha particles emitted by radon decay products are counted in the proportional region of the counter by ionization produced in the counting gas. This method can be applied to any gas containing radon and the detection limit that can be achieved with this method is equal to 6 Bq m −3 .