The determination of 161Tb activity is problematic due to its very low fission yield, short half-life, and the complication of its gamma spectrum. At AWE, radiochemically purified 161Tb solution was measured on a PerkinElmer 1220 QuantulusTM Liquid Scintillation Spectrometer. Since there was no 161Tb certified standard solution available commercially, the counting efficiency was determined by the CIEMAT/NIST Efficiency Tracing method. The method was validated during a recent inter-laboratory comparison exercise involving the analysis of a uranium sample irradiated with thermal neutrons. The measured 161Tb result was in excellent agreement with the result using gamma spectrometry and the result obtained by Pacific Northwest National Laboratory.

中文翻译：

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通过放射化学分离和液体闪烁计数分析161Tb。

161Tb活性的确定是有问题的，因为它的裂变产率非常低，半衰期短，并且其伽马谱很复杂。在AWE，用PerkinElmer 1220 QuantulusTM液体闪烁光谱仪测量放射化学纯化的161Tb溶液。由于没有可商购的161Tb认证标准溶液，因此计数效率由CIEMAT / NIST效率跟踪方法确定。该方法在最近的实验室间比较实验中得到了验证，该实验涉及对用热中子辐照的铀样品进行分析。测得的161Tb结果与使用伽马能谱法和太平洋西北国家实验室获得的结果非常吻合。