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

• Published in: Nuclear data sheets Vol. 196; pp. 1 - 11
• Main Authors: Pommé, S., Stroh, H., Paepen, J.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.08.2024
• ISSN: 0090-3752
• DOI: 10.1016/j.nds.2024.06.001

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.