Fast and accurate dating of nuclear events using La-140/Ba-140 isotopic activity ratio

This study reports on a fast and accurate assessment of zero time of certain nuclear events using La-140/Ba-140 isotopic activity ratio. For a non-steady nuclear fission reaction, the dating is not possible. For the hypothesis of a nuclear explosion and for a release from a steady state nuclear fission reaction the zero-times will differ. This assessment is fast, because we propose some constants that can be used directly for the calculation of zero time and its upper and lower age limits. The assessment is accurate because of the calculation of zero time using a mathematical method, namely the weighted least-squares method, to evaluate an average value of the age of a nuclear event. This was done using two databases that exhibit differences between the values of some nuclear parameters. As an example, the calculation method is applied for the detection of radionuclides La-140 and Ba-140 in May 2010 at the radionuclides station JPP37 (Okinawa Island, Japan). - Highlights: • Issues related to the use of nuclear data in calculation of age of nuclear events are presented. • We propose some constants for a fast and accurate assessment of the age of a nuclear event using La-140/Ba-140 activity ratio. • The weighted least-squares method is used to obtain more accuracy of zero time.