222Rn/220Rn绝对测量小闪烁室的ZnS(Ag)涂层厚度确定

ZnS(Ag)涂层厚度会影响222 Rn/220 Rn绝对测量小闪烁室的探测效率.用241 Amα电镀参考源对厚度为10 mg/cm2的ZnS(Ag)涂层α探测效率进行了实验验证.分别采用解析方法与MCNP模拟方法计算了相对立体角修正因子,讨论了空气层对α粒子的吸收修正,分析了不确定度来源.实验结果表明,10 mg/cm2 ZnS(Ag)涂层对α粒子的探测效率在102.4%～103.1%之间,不确定度小于5.44%.在实验不确定度范围内,可认为其对α粒子的探测效率为100%.实验证明了222Rn/220Rn绝对测量小闪烁室内采用10 mg/cm2厚的ZnS(Ag)涂层是可行的.

ZnS(Ag) Coating Layer Thickness Verification of One Small Scintillation Cell for 222Rn/220Rn Absolute Measurement

The detection efficiency of one small scintillation cell for 222Rn/220Rn absolute measurement can be affected by ZnS(Ag) coating layer thickness on the inner wall of the small scintillation cell.The α detection efficiency of 10 mg/cm2 thickness ZnS(Ag) coating layer has been tested and verified using a plating reference source(241Am).The solid angle correction factor is calculated by analysis and MCNP simulation methods.The absorption correction of air layer on α particle has been discussed.The source of uncertainty has been analysed.The results indicate the α detection efficiency of 10 mg/cm2 thickness ZnS(Ag) coating layer is between 102.4%~103.1% while the uncertainty is less than 5.44%.In the uncertain range α detection efficiency of it is considered as 100%.10 mg/cm2 thickness ZnS(Ag) coating layer can be used to apply on the inner wall of the small scintillation cell for222Rn/220Rn absolute measurement.