^(220)Rn累积测量的吸收体法及其应用

An integrated thoron monitoring method with absorber and its applications

利用220Rn子体ThC’衰变产生的α粒子能量较氡及其子体衰变产生的α粒子能量都高的特点,发展了一种220Rn测量的吸收体方法。本文介绍了加吸收体甄别氡及实现220Rn直接测量的原理、剂量计及其刻度方法。该剂量计测量220Rn暴露量和介质表面220Rn析出率的刻度系数分别为R0=0.0767cm–2(kBq·m–3·h)–1和R=0.1300cm–2(kBq·m–3·h)–1。当测量周期7d,所用CR-39本底径迹密度标准差ST=1.6cm–2时,其测220Rn浓度与220Rn析出率的探测下限分别为LLDC=248.4Bq·m–3和LLDE=34.8mBq·m–2·s–1。220Rn累积测量的吸收体法在环境220Rn水平测量、室内220Rn及其子体水平分布测量和介质表面220Rn析出率测量中得到了应用。

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.