Measurement of the 134Cs half-life in support of the exponential-decay law

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 204 565 and 99 486 ionisation current measurements with a reproducibility of the order of 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 754.207 (48) d or 2.06496 (13) a, with a relative uncertainty of 0.0064%. 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.

POMME Stefaan;  STROH Heiko;  PAEPEN Jan; 

2024-07-18

ACADEMIC PRESS INC ELSEVIER SCIENCE

JRC135418

0090-3752 (online),   

https://doi.org/10.1016/j.nds.2024.06.001,    https://www.sciencedirect.com/science/article/pii/S0090375224000383?via%3Dihub,    https://publications.jrc.ec.europa.eu/repository/handle/JRC135418,   

10.1016/j.nds.2024.06.001 (online),