Radon Equilibrium Measurement in the Air

This paper presents the exact method for radon equilibrium determination by gamma spectrometry measuring of radon progeny concentrations in the air. The method is based on simultaneous sampling of air through the filter paper and alpha spectrometry measurement of radon activity concentration in the air. This paper derived a mathematical formula to calculate the initial concentrations of radon progenies Po, Pb and Bi in the air at the start of sampling based on the detected count rate of post radon gamma lines in the sample of filter paper. Such a model containing the radioactive decay corrections during the time of sampling, cooling and measurement can be applied in other nuclear analysis where the half-life of the source has the same order of magnitude as the available recording time.