低压闪烁室对220Rn浓度参考水平定值的方法

²²⁰Rn的准确测量是天然辐射照射剂量评价体系中的重要研究内容之一。普通闪烁室体积较大，对²²²Rn、²²⁰Rn及其子体衰变产生的不同能量的高能α粒子具有不同的探测效率。本文提出调低标准闪烁室内气压，使²²²Rn衰变产生的能量最小的α粒子在闪烁室内的射程大于闪烁室内任意两点间最长距离，这样，低压闪烁室对²²²Rn、²²⁰Rn及其子体衰变产生的α粒子探测效率相同。利用标准氡室可得到低压闪烁室对α粒子探测效率，进而可使用低压闪烁室对²²⁰Rn浓度参考水平定值。

Method for Determination of 220Rn Concentration Reference Value by Low-pressure Scintillation Cell

The accurate measurement of ²²⁰Rn is important for dosimetry evaluation of natural radiation exposure. The detection efficiencies of normal scintillation cell to different energy α particles decayed from ²²²Rn, ²²⁰Rn and their daughters are different for the large volume of normal scintillation cell. It was proposed that the range of  α particles with minimum energy decayed from ²²²Rn could be longer than the longest distance between any two points in the scintillation cell by reducing the air pressure of scintillation cell. Thus, the detection efficiencies of the low-pressure scintillation cell to α particles decayed from ²²²Rn, ²²⁰Rn and their daughters are same. The detection efficiency of low-pressure scintillation cell to α particles can be obtained by standard radon chamber, and then the ²²⁰Rn concentration reference value can be determined by low-pressure scintillation cell.