Measurement of the 225Ac half-life

The (225)Ac half-life was determined by measuring the activity of (225)Ac sources as a function of time, using various detection techniques: α-particle counting with a planar silicon detector at a defined small solid angle and in a nearly-2π geometry, 4πα+β counting with a windowless CsI sandwich spectrometer and with a pressurised proportional counter, gamma-ray spectrometry with a HPGe detector and with a NaI(Tl) well detector. Depending on the technique, the decay was followed for 59-141d, which is about 6-14 times the (225)Ac half-life. The six measurement results were in good mutual agreement and their mean value is T(1/2)((225)Ac)=9.920 (3)d. This half-life value is more precise and better documented than the currently recommended value of 10.0d, based on two old measurements lacking uncertainty evaluations.

POMME Stefaan;  MAROULI Maria;  SULIMAN Gabriel;  DIKMEN Hasan;  VAN AMMEL Raf;  JOBBAGY Viktor;  DIRICAN A.;  STROH Heiko;  PAEPEN Jan;  BRUCHERTSEIFER Frank;  APOSTOLIDIS Christos;  MORGENSTERN Alfred; 

2012-10-15

PERGAMON-ELSEVIER SCIENCE LTD

JRC70908

0969-8043,   

http://www.sciencedirect.com/science/article/pii/S0969804312004472,    https://publications.jrc.ec.europa.eu/repository/handle/JRC70908,   

10.1016/j.apradiso.2012.07.014,