A comparison on commercially available radon (²²²Rn) measuring instruments (three types of continuous monitors and a passive ²²²Rn-thoron (²²⁰Rn) discriminative alpha track detector) was carried out at low-level concentrations in one room of a concrete building. The agreements between the continuous monitors were within 15%, while the agreements between each instrument were within 20%. It was also observed that the indoor ²²⁰Rn concentration measured by the continuous monitor was quite different from those by the passive detectors due to the mean concentration less than the limit of detection of both measuring instruments.

中文翻译：

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在日本混凝土建筑的一个房间中进行低浓度氡和钍测量仪器的比较实验

对商用氡 ( ²²² Rn) 测量仪器（三种类型的连续监测器和无源²²² Rn-钍 ( ²²⁰ Rn) 判别式 α 径迹探测器）在混凝土建筑物的一个房间内进行了低浓度的比较。连续监测器之间的一致性在15%以内，而每个仪器之间的一致性在20%以内。还观察到，连续监测器测量的室内²²⁰ Rn 浓度与被动探测器测量的室内²²⁰ Rn 浓度有很大差异，因为平均浓度低于两种测量仪器的检测限。