Half-life of 90Sr — measurement and critical review

Abstract

Recent evaluations of the half-life of 90Sr have demonstrated the variable quality of the available experimental data which has prevented the estimation and adoption of a value that commands confidence. In an attempt to reduce the uncertainty in the half-life to an acceptable level, the decay of a 90Sr source has been followed for over six years at NPL. The equipment comprised matching, re-entrant, high-pressure ionization chambers and a long-lived reference source to reduce non-random effects. The experimental technique is described together with the statistical procedure used to analyse the measured data. A half-life value was determined together with an estimate of the associated uncertainties. A new evaluation of the 90Sr half-life has been made, taking account of the new NPL data and other recent measurements. Particular attention has been paid to the experimental techniques used to produce the data and the uncertainties attributed to them. An objective evaluation has been conducted to produce a new recommended half-life value of 10 516 ± 21 days.