The half-life of 134Cs has been determined through 882 and 471 activity measurements of two sources over 12 years with a re-entrant ionisation chamber in a temperature-stabilised room. The data were aggregated from in total 204565 and 99486 ionisation current measurements with 0.057% standard deviation. The decay curves adhere to the exponential-decay law, devoid of any cyclic perturbations at daily, monthly, and multi-annual scales, maintaining an exceptionally low standard deviation of 0.0003% on the amplitude. A discernible annual cycle with an amplitude of 0.0051 (3)% was effectively mitigated to an insignificant level of 0.0009(3)% by compensating the residuals proportionally to daily variations in ambient humidity. The study yielded a half-life value for 134Cs of 754.200(53)d or 2.06493(14)a, with a relative standard uncertainty of 0.0070%. The result obtained in this work can be recommended as a reference value, owing to its high statistical accuracy and conservative estimate of systematic errors.

中文翻译：

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支持指数衰减定律的 134Cs 半衰期测量


134C 的半衰期是通过在温度稳定室中对两个离子源进行 882 年和 471 次活性测量来确定的，为期 12 年。数据是从总 204565 和 99486 电离电流测量值中汇总的，标准偏差为 0.057%。衰减曲线遵循指数衰减定律，在每日、每月和多年尺度上没有任何周期性扰动，保持振幅 0.0003% 的极低标准差。通过按环境湿度的每日变化成比例补偿残差，有效地将振幅为 0.0051 （3）% 的可识别年周期减轻到 0.0009（3）% 的微不足道的水平。该研究得出 134Cs 的半衰期值为 754.200（53）d 或 2.06493（14）a，相对标准不确定性为 0.0070%。这项工作中获得的结果可以推荐作为参考值，因为它具有很高的统计准确性和对系统误差的保守估计。