高纯锗γ谱仪对碘采集装置中131I的探测效率研究

校准气载放射性碘监测设备参考响应的测量标准,是以放射性碘采集装置为源载体的¹³¹I参考源,其量值采用γ能谱法测定。γ谱仪对采集装置中¹³¹I的探测效率是¹³¹I参考源准确定值的关键参数。本研究针对测量用的相对效率为53%的N型同轴高纯锗γ谱仪,刻度了其对采集装置中¹³¹I的探测效率。结果表明,该γ谱仪对玻璃纤维滤纸与活性炭滤纸表面¹³¹I的探测效率为7.68%,对浸渍活性炭滤盒不同深度处探测效率变化范围为(3.14~7.68)%,当分布参数在(0.09~0.34) mm^-1之间变化时,采用该高纯锗γ谱仪测量,浸渍活性炭滤盒的η_count·η_collection值在(4.90~6.82)%间变化。

Detection Efficiency of N-Type Coaxial HPGe for Measuring 131I in Iodine Collection Device

The measurement standard which used for radioactive iodine monitor equipment reference response calibration is a ¹³¹I reference source which use radioactive iodine collection device as source carrier. Generally,the ¹³¹I reference source is quantified by using gamma spectrometer method. Therefore,the detection efficiency of gamma spectrometer for ¹³¹I in collection device is a key parameter in accurate quantification of ¹³¹I reference source. In this paper,we studied the detection efficiency of N-type coaxial HPGe with a relative detection efficiency of 53% for ¹³¹I in collection device. The results show that the gamma detection efficiency of this HPGe for ¹³¹I on glass fibrous filter or active carbon filter is 7.68%,and the gamma detection efficiency of this HPGe for ¹³¹I in different depth of impregnated activated carbon filter cartridge ranged from 3.14% to 7.68%. The η_cou·η_col value ranged from 4.90% to 6.82%,while the distribution parameter changed from 0.09 mm^-1 to 0.34 mm^-1.