Fitzgerald R, Collé R, Laureano-Pérez L, Pibida L, Hammond M M, Nour S, Zimmerman B E
Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Appl Radiat Isot. 2010 Jul-Aug;68(7-8):1303-8; discussion 1308. doi: 10.1016/j.apradiso.2010.01.007. Epub 2010 Jan 13.
The National Institute of Standards and Technology (NIST) has certified a high-purity (229)Th Standard Reference Material as SRM 4328C, based on live-timed 4pialphabeta-gamma anticoincidence counting (LTAC) of the equilibrium solution. The LTAC system was optimized to minimize the uncertainty in the result due to the two short-lived ground-states present in the decay chain. Confirmatory measurements were carried out by four other methods. Furthermore, the present absolute activity and measured gamma-ray emission rates were combined to obtain gamma-ray emission probabilities.
美国国家标准与技术研究院（NIST）已将一种高纯度（229）钍标准参考物质认证为SRM 4328C，该认证基于对平衡溶液进行实时4π αβγ 反符合计数（LTAC）。LTAC系统经过优化，以尽量减少由于衰变链中存在的两个短寿命基态而导致的结果不确定性。通过其他四种方法进行了验证性测量。此外，将当前的绝对活度和测得的伽马射线发射率相结合，以获得伽马射线发射概率。
