Bias in U decay chain members measured by γ-ray spectrometry due to Rn leakage.

In this work we investigate and quantify how effectively the noble gas Rn is trapped inside measurement beakers used in high-resolution gamma-ray spectrometry. We test six types of different beakers commonly utilized in γ spectrometry, including one novel construction, the γBeaker. We assessed Rn leakage by injecting Rn rich air into the examined beakers and investigated the abnormal decrease in Rn daughters - Pb and Bi. The measured decay times were used to estimate the Rn leakage. In addition, we investigated the influence of an additional beaker sealed with tape. However, the additional beaker sealing only slightly reduced the Rn escape and was not reproducible. Almost every tested beaker exhibited heavy Rn leakage. This may lead to an underestimation and radioactivity over-dispersion of U decay chain members when they are measured via their Rn daughter products.