Application of the most frequent value method for

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

Ambient Dose and Dose Rate Measurement in SNOLAB Underground Laboratory at Sudbury, Ontario, Canada

The paper describes a system and experimental procedure that use integrating passive detectors, such as thermoluminescent dosimeters (TLDs), for the measurement of ultra-low-level ambient dose equivalent rate values at the underground SNOLAB facility located in Sudbury, Ontario, Canada. Because these detectors are passive and can be exposed for relatively long periods of time, they can provide better sensitivity for measuring ultra-low activity levels. The final characterization of ultra-low-level ambient dose around water shielding for ongoing direct dark matter search experiments in Cube Hall at SNOLAB underground laboratory is given. The conclusion is that TLDs provide reliable results in the measurement of the ultra-low-level environmental radiation background