Determination of the ${}^{229}\mathrm{Th}$ half-life

The paper describes the remeasurement of the half-life of ${}^{229}\mathrm{Th}$ (ground state). The half-life was obtained by the measurement of amount content of ${}^{229}\mathrm{Th}$ in the certified ${}^{229}\mathrm{Th}$ radioactivity standard (SRM 4328C) from the National Institute of Standards and Technology. The measurement was performed by isotope dilution inductively coupled plasma mass spectrometry by using two independent standards for quantification. From the results the ${}^{229}\mathrm{Th}$ half-life is determined to be 7917 years with an expanded uncertainty of 48 years using a coverage factor of $k=2$. The methodology is traceable to the International System of Units, and the calculation complies with the recommendations of the Bureau International des Poids et Mesures for nuclear data evaluation.

Figure 1

The obtained half-life values in comparison with the reported values. All uncertainties are expressed at a confidence level of 2σ or as expanded uncertainties with a coverage factor of $k=2$.