Examination for the Calibration Method of Passive-type Radon Progeny Monitor in Some Experimental Conditions

Abstract

The conversion factor (CF) from track density (Ti) of CR-39 to exposure to radon progeny for the passive-type radon progeny monitor (progeny monitor) was determined theoretically (5.0×10⁵ track mm^-2 per J m^-3 day)¹⁾. In this study, calibration experiments for the progeny monitors were performed in the radon exposure chamber and indoor environments, a hot spring facility in Hokkaido, and a dwelling in Aomori. The progeny monitors and a Portable Environmental Radiation/Radioactivity Monitor (PERRM) were installed at each site. After the measurements, CFs were calculated based on Ti and potential alpha energy concentration (PAEC) obtained by the progeny monitors and PERRM, respectively. As a result, CFs ranged from 1.4 × 10⁶ to 15 × 10⁶ track mm^-2 per J m^-3 day depending on the experimental sites. This study suggested that CF should be characterized and a suitable CF should be related to environmental conditions, such as an unattached fraction of radon progeny, aerosol conditions, etc. Therefore, it is necessary to evaluate CFs with these conditions in further studies.