A method for evaluating the concentration of alpha radiation potential energy of thoron 220Rn in the air

Assumptions and a description of an improved method for measuring the potential energy of radon decay products in the air are given. The method is based on the detection of alpha radiation emitted by ThC', in properly selected time intervals after the process of air filtration, i.e. after collecting thoron decay products on the filter. The method has been worked out for various duration of filtration, i.e. 1-15 min, with measuring time intervals from 10 to 180 min. The method obtained may be applied for the measurements of concentrations in a wide range of variation. Radioactivity of the deposit is being calculated on the basis of comparative measurements of 239Pu source of known activity. The sensitivity of the method for the most sensitive range is 0.84x104 MeV/litre per 1 liter of air filtered. (author)