The influence of thoron and its progeny on radon measurements with CR39 detectors in diffusion chambers

In this work partial and total sensitivities of the CR39 detector to thoron and its progenies are determined by the Monte Carlo method. It has been shown that the total sensitivity to thoron is higher than that to radon, with the difference in the sensitivities depending on the dimension and the shape of the diffusion chamber used in measurements. The presence of thoron in air causes an overestimation of the measured radon values. The overestimation has been found to increase linearly with the ratio of thoron/radon concentrations and to depend on height and radius of the diffusion chamber.