A new evaluation of the half-life of 241Pu has been made by developing earlier methods and techniques and employing further measurements of the isotopic ratio of an initially enriched 241Pu material. A correction to the previous value has had to be made. The half-life of 241Pu is an important parameter for the measurement and control of amounts of plutonium as the decay of this isotope is usually the largest contributor to the uncertainty of estimations of the amount of total plutonium after storage. The value of the half-life together with its associated uncertainty need to be known with a high degree of confidence. The value of the half-life also raises problems of methodology in its determination as it is too long for the specific activity of a sample to be measured by one laboratory using a single method or instrument over a time period commensurate with one or more half-lives. The method employed is designed to conform to the Guide to the Estimation of Uncertainty in Measurements (GUM)  and care was taken to ensure that all measured values over the 30 year measurement time-span have been included. The value recommended from this set of measurements is 14.325 +/- 0.024 a (k=2).
, Verbruggen, A.
and Kessel, R.
A New Evaluation of the Half-life of 241Pu, Journal of Analytical Atomic Spectrometry, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=900917
(Accessed June 4, 2023)