Application of the most frequent value method for 39Ar half-life determination

An evaluation method supported by robust statistical analysis was applied to historical measurements of Ar-39 half-life. The method, based on the most frequent value (MFV) approach combined with bootstrap analysis, provides a more robust way to estimate Ar-39 half-life, and results in T1/2(MFV) = 268.2+(3.1) -(2.9) years with uncertainty corresponding to the 68% confidence level. The uncertainty is a factor of 3 smaller than that of the most precise re-calculated Ar-39 half-life measurements by Stoenner et al. and a factor of 2.7 smaller than that of the adopted half-life value in nuclear data sheets. Recently, the specific activity of the beta decay of 39Ar in atmospheric argon was measured in several underground facilities. Applying the MFV method to a specific activity of Ar-39 from underground measurements results in SA(39)Ar/Ar(MFV) = 0.966+(0.010) (-0.018) Bq/kgatmAr with uncertainty corresponding to the 68% confidence level. In this paper themethod to determine the half-life of Ar-39 using the specific activity of Ar-39 in atmospheric argon is also discussed.

Automated summary

This study applied an evaluation method supported by robust statistical analysis to historical measurements of Ar-39 half-life and obtained more reliable estimates. Additionally, the method to determine the half-life of Ar-39 using the specific activity of Ar-39 in atmospheric argon was discussed.