An integrated thoron measurement method with absorber was developed based on the characteristic of thorium C’ which emits an α particle with higher energy than that of α particles released from radon and radon progenies. The principle of discriminating radon and realizing thoron measurement with absorber

a passive and integrated thoron monitor developed and its calibration method are introduced. The calibration coefficients of the monitor are R0=0.0767cm–2 (kBq·m–3·h) –1 for thoron exposure measurement and R=0.1300 cm–2(kBq·m–3·h) –1 for thoron exhalation rate measurement. The lower limits of detection are LLDC=248.4 Bq·m–3 and LLDE=34.8 mBq·m–2·s–1 when the sampling period is 7 days and the deviation of background track densities of the adopted CR-39 is ST=1.6 cm–2. The method was used for the measurement of environmental thoron concentrations

the distribution of indoor thoron and its progenies concentrations

and thoron exhalation rates on material surfaces.