Improvement and verification of new measurement methods for radon and thoron progeny activity concentration based on alpha spectrometry analysis

For accurate dose evaluation of radon and thoron exposure, it is important to find a more effective method to measure radon and thoron progeny activity concentration in field measurements. For the purpose of improving measurement sensitivity, two new alpha spectrometry methods, the Wicke-Tn and PKU-Tn methods, for radon as well as thoron progeny were proposed and a series of verification experiments carried out in different environments. Results showed that the two new methods both gave accurate radon and thoron progeny activity concentration individually, and the methodological sensitivity and uncertainty were greatly improved. In an experimental mixed radon–thoron environment, the methodological sensitivity of the PKU-Tn and Wicke-Tn methods were nearly 9.0 and 3.6 times higher than that of the Kerr-Tn method, respectively. Among the three methods, the PKU-Tn method had the highest methodological sensitivity and lowest uncertainty, indicating its prospects for use in field measurement. •Two new α spectrometry methods, the Wicke-Tn and PKU-Tn methods, for radon and thoron progeny concentrations measurement.•Higher methodological sensitivity, lower uncertainty and lower detection limit.•Measurement cycle of 3 h for field measurement.