Pommé S, Marouli M, Suliman G, Dikmen H, Van Ammel R, Jobbágy V, Dirican A, Stroh H, Paepen J, Bruchertseifer F, Apostolidis C, Morgenstern A
European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium.
Appl Radiat Isot. 2012 Nov;70(11):2608-14. doi: 10.1016/j.apradiso.2012.07.014. Epub 2012 Jul 25.
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 59-141 d, 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 10.0 d, based on two old measurements lacking uncertainty evaluations.
通过使用各种检测技术测量（225）Ac源的活度随时间的变化，来确定（225）Ac的半衰期：在定义的小立体角和近2π几何条件下，使用平面硅探测器进行α粒子计数；使用无窗CsI夹心光谱仪和加压正比计数器进行4πα + β计数；使用HPGe探测器和NaI（Tl）井型探测器进行γ射线光谱分析。根据技术不同，对衰变进行了59 - 141天的跟踪，这大约是（225）Ac半衰期的6 - 14倍。六个测量结果相互吻合良好，其平均值为T（1/2）（（225）Ac）= 9.920（3）天。与目前推荐的10.0天的值相比，这个半衰期值更精确且记录更完善，后者基于两项缺乏不确定度评估的旧测量。
