Study of Detection Efficiency of ²²²Rn Samples Obtained by Active Activated Charcoal by HPGe γ Spectrometry

In active adsorption of activated charcoal, it is uneven distribution of ²²²Rn in the collector in different adsorption time, which makes impact on efficiency calibration by HPGe γ spectrometry. By the adsorption experiment of active double-membrane activated charcoal in the standard radon chamber, the relationship between detection efficiencies of different energy characteristics of the γ-ray and counting relative deviation of ²²²Rn from import and export side of the double-membrane activated charcoal collector by HPGe γ spectrometry in different adsorption time was obtained, which is linear. The absolute value of relative deviation of adsorption capacity for ²²²Rn is less than 5% between calculated and measured, which is to verify the correctness and reliability of the method of active double-membrane activated charcoal.