Pommé S, Suliman G, Marouli M, Van Ammel R, Jobbágy V, Paepen J, Stroh H, Apostolidis C, Abbas K, Morgenstern A
European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium.
Appl Radiat Isot. 2012 Sep;70(9):1913-8. doi: 10.1016/j.apradiso.2012.02.117. Epub 2012 Mar 7.
The half-lives of (226)Th and (222)Ra were measured by counting alpha-particle emissions from sources as a function of time. The (226)Th sources were prepared from an open (230)U source, capturing recoil atoms after alpha-particle decay on glass disks or even directly onto a detector. Similarly, the (222)Ra sources were obtained by self-transfer of recoil atoms from (226)Th sources. The activity measurements were performed in (nearly-)2π geometry with an ion-implanted silicon detector. The decay curves were analysed in different ways, incl. moment analysis, trying to avoid the pitfalls of bias of least-squares fits to Poisson distributed data. The observed half-life values are T(1/2)((226)Th)=30.70 (3) min and T(1/2)((222)Ra)=33.6 (4) s. Literature values show some inconsistency.
