^(222)Rn-^(220)Rn分辨探测器的刻度与比对

Calibration and intercomparison for radon-thoton discriminative detector

为了保证测量质量,采用实验室新改进的222Rn-220Rn分辨探测器在南华大学氡实验室进行了刻度,并参加了日本NIRS组织的国际比对。结果显示,222Rn、220Rn暴露量与径迹密度之间有很好的线性关系,相关系数分别是0.9894、0.9885;222Rn、220Rn刻度因子分别为4.27±0.40Tackscm-2(kBq·m-3·h)–1、2.33±0.39Trackscm-2(kBq·m-3·h)–1。纯222Rn条件,测量值与NIRS提供的参考值的相对百分偏差(RPD)和变异系数(COV)分别为12%、7.7%,达到了英国NRPB规定的B级水平,在美国EPA规定的可接受的控制限之内;高220Rn条件,220Rn测量值的RPD和COV分别为22%、4.8%。有关220Rn测量偏差偏高的原因有待进一步探讨。

To guarantee the quality of measurements, the radon-thoron discriminative detector improved by our laboratory was calibrated at Radon Laboratory of University of South China, and participated in the international intercomparison organized by NIRS（National Institute of Radiological Sciences）in Japan. The calibration result demonstrated that correlation between the exposure level and the track density was fairly good for both radon and thoron, with the correlation coefficient of 0.9894 and 0.9885, and the calibration factors of 4.27±0.40 and 2.33 ±0.39 tracks.cm^-2.（kBq.m^-3.h）^-1 for radon and thoron, respectively. According to the results of inter-comparison, in pure radon, relative percent difference from the reference value （RPD） was 12% and coefficient of variation （COV） was 7.7%, ranking category B of NRPB, and was in the control level of EPA; while in high ^220Rn condition, RPD and COV for thoron were 22% and 4.8%, respectively. Concerning the higher deviation for thoron measurement, the cause should be further discussed.