New measurements of the half-life of ²²⁵Ac at the NPL and IRA.
Durán MT, Collins S, Nedjadi Y, Juget F, Mohamud H, Bhaisare A (+1 more)
Abstract
The half-life of ²²⁵Ac has been determined by the National Physical Laboratory (NPL) and Institute de Radiophysique (IRA). At IRA, using ²²⁵Ac extracted from a²²⁹Th generator, the decay of 225Ac was followed using two gamma-ray scintillation detectors, a well-type NaI(Tl) and CeBr₃ detectors. A mean half-life of 9.9225(44) d was determined. The NPL performed decay measurement campaigns, from ²²⁵Ac extracted from ²²⁵Ra that had been produced via mass-separation, using a high-purity germanium gamma-ray spectrometer. A half-life of 9.9195(50) d was derived from the weighted mean of the two gamma ray regions of interest. These values are compatible with recent published data and with the evaluated half-life determined in the ENSDF and DDEP databases, with values of 9.920(3) d and 9.9172(21) d, respectively.