Radon and thoron progeny integrated measurement based on high-voltage sampling

For the purpose of directly measuring radon and thoron progeny concentrations simultaneously, an unattended battery-operated progeny measurement (UBPM) device, which samples aerosol particles in an electric field, was improved by adopting two different thickness aluminum foils for alpha particles discriminating. The equations for the calculation of the results were derived, and a series of calibration experiments and comparison tests were carried out in the potential alpha energy concentration calibration chamber in BfS Berlin and the HMGU experimental thoron house, respectively. Results show that the calibration coefficients are stable in different levels of radon and thoron progeny. The lower level detection limits of the device for radon and thoron progeny concentration are 1.22 and 0.14 Bq m^-3, respectively, for three months exposure. The instrument proved to be independent from environmental conditions in ordinary living room conditions (humidity <65% RH, aerosol particle concentration >1500 cm^-1). Comparison results show that the measurement results of the UBPM device are comparable with the reference instrument and suitable for long-term radon and thoron survey in dwellings. (author)