Half-Life Of Re-184 Populated By Photodisintegration Reaction With Laser Compton Scattering Gamma-Rays At Newsubaru

We report a half-life of the ground state of Re-184 populated by the Re-185(gamma,n) Re-184 reaction with the Laser Compton scattering gamma-rays generated through relativistic engineering. The gamma rays are provided at the electron storage ring NewSUBARU. The half-life of the 3(-) ground state of Re-184, 38.0 +/- 0.5 d, has been taken as a recommended value, which was measured using deuteron-induced reactions. However, this half-life may include a possible contribution from the 8(+) isomer (T-1/2 = 169 +/- 8 d) of Re-184 since the presence of the isomer was not known at that time. In contrast, the (gamma,n) reaction has the advantage to selectively populate the ground state because this reaction does not bring large angular momentum. The measured half-life of 35.4 +/- 0.7 d is shorter than the previous half-life by about 7%. This difference is crucial for applications using the activation method.