Estimation of radiative half-life of Th229m by half-life measurement of other nuclear excited states in Th229

Y. Shigekawa, A. Yamaguchi, K. Suzuki, H. Haba, T. Hiraki, H. Kikunaga, T. Masuda, S. Nishimura, N. Sasao, A. Yoshimi, K. Yoshimura
2021 Physical Review C  
We perform coincidence measurements between α particles and γ rays from a ^233U source to determine the half-lives of the excited state in a ^229Th nucleus. We first prove that the half-lives of 42.43- and 164.53-keV states are consistent with literature values, whereas that of the 97.14-keV state (93(7) ps) deviates from a previously measured value (147(12) ps). The half-lives of 71.83- and 163.25-keV states are determined for the first time. Based on the obtained half-lives and the Alaga
more » ... we estimate the radiative half-life of the low-energy isomeric state (^229mTh) to be 5.0(11)×10^3 s, which is one of the key parameters for the frequency standard based on ^229Th.
doi:10.1103/physrevc.104.024306 fatcat:nbvquug4wneuhkujgvt4egpxje