Determination of the half-life of 184gRe and the isomeric ratio of 184m, gRe induced by D-T neutrons

The isomeric ratio of Re-184(m,) g and the half-life of Re-184g were measured in the Re-185 (n, 2n) Re-184 reaction at 14.8 MeV, and the uncertainty was discussed in detail. The measurements were performed using the activation method implemented for a rhenium sample using the K-400 neutron generator at the Chinese Academy of Engineering Physics (CAEP). Isomeric state and ground state nuclei of Re-184 were identified by their gamma-ray spectra. To eliminate the effect of the gamma-ray emitted from the isomer on the counting of the ground state characteristic peaks, the isomeric ratio of Re-184m,Re- g was calculated to be 0.29 +/- 0.11 according to the neutron activation cross-section formula. This result is consistent with previous data within the uncertainty and can be used to determine parameters that characterize the dependence of the level density on the excitation energy and angular momentum. Through exponential function fitting and a detailed discussion of the uncertainty evaluation, the half-life of Re-184g was determined as 35.43 +/- 0.16 d, which is consistent with the currently recommended value; however, the uncertainty assessment of the latter was barely documented. In addition, this study indicates that the half-life of the ground state can be obtained by eliminating the contamination of gamma-rays emitted from the isomer, which provides the possibility of determining the half-lives of nuclides containing isomers.

Automated summary

The isomeric ratio and half-life of Re-184 were measured and the uncertainty was discussed. The results are consistent with previous data and can be used to determine parameters characterizing the level density. The study also found that the half-life of the ground state can be obtained by eliminating contamination from gamma-rays emitted by the isomer.