The procedure followed by the Nuclear Metrology Laboratory (LMN) at the IPEN-CNEN/SP, in São Paulo, for the primary standardization of ¹⁶⁶Ho is described. The activity of ¹⁶⁶Ho was determined by the efficiency extrapolation technique applied to a 4πβ(PC)-γ coincidence system using a gas flow proportional counter in 4π geometry coupled to a 76 × 76 mm NaI(Tl) crystal. The results for the γ-rays intensities at 80.57 and 1379.45 keV were 0.0651(11) and 0.00904(11), respectively.

中文翻译：

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Ho-166 伽马射线发射强度的初步标准化和测定。

描述了圣保罗 IPEN-CNEN/SP 核计量实验室 (LMN) 对¹⁶⁶ Ho的主要标准化所遵循的程序。¹⁶⁶ Ho的活性是通过应用于 4πβ(PC)-γ 符合系统的效率外推技术确定的，该技术使用与 76 × 76 mm NaI(Tl) 晶体耦合的 4π 几何形状的气流正比计数器。80.57 和 1379.45 keV 的 γ 射线强度结果分别为 0.0651(11) 和 0.00904(11)。