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

Abstract

An evaluation method supported by robust statistical analysis was applied to historical measurements of ^{39}Ar half-life. The method, based on the most frequent value (MFV) approach combined with bootstrap analysis, provides a more robust way to estimate ^{39}Ar half-life, and results in T_{1/2}(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 ^{39}Ar 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 ^{39}Ar in atmospheric argon was measured in several underground facilities. Applying the MFV method to a specific activity of ^{39}Ar from underground measurements results in SA_{{^{39}text {Ar}}/text {Ar}}(text {MFV}) = 0.966^{+0.010}_{-0.018} , , text {Bq/kg}_{text {atmAr}} with uncertainty corresponding to the 68% confidence level. In this paper the method to determine the half-life of ^{39}Ar using the specific activity of ^{39}Ar in atmospheric argon is also discussed.