Balpardo C, Capoulat M E, Rodrigues D, Arenillas P
Laboratorio de Metrología de Radioisótopos, CNEA, Buenos Aires, Argentina.
Appl Radiat Isot. 2010 Jul-Aug;68(7-8):1358-61. doi: 10.1016/j.apradiso.2009.12.010. Epub 2009 Dec 23.
The nuclide (241)Am decays by alpha emission to (237)Np. Most of the decays (84.6%) populate the excited level of (237)Np with energy of 59.54 keV. Digital coincidence counting was applied to standardize a solution of (241)Am by alpha-gamma coincidence counting with efficiency extrapolation. Electronic discrimination was implemented with a pressurized proportional counter and the results were compared with two other independent techniques: Liquid scintillation counting using the logical sum of double coincidences in a TDCR array and defined solid angle counting taking into account activity inhomogeneity in the active deposit. The results show consistency between the three methods within a limit of a 0.3%. An ampoule of this solution will be sent to the International Reference System (SIR) during 2009. Uncertainties were analysed and compared in detail for the three applied methods.
核素（241）Am通过α衰变生成（237）Np。大部分衰变（84.6%）产生能量为59.54 keV的（237）Np激发态。采用数字符合计数法，通过α-γ符合计数及效率外推对（241）Am溶液进行标准化。使用加压正比计数器进行电子甄别，并将结果与另外两种独立技术进行比较：一种是利用TDCR阵列中双符合逻辑和的液体闪烁计数，另一种是考虑活性沉积物中活度不均匀性的定义立体角计数。结果表明，三种方法之间的一致性在0.3%的限度内。该溶液的一个安瓿将于2009年送交国际参考系统（SIR）。对三种应用方法的不确定度进行了详细分析和比较。
