Half-life of Re populated by the reaction from laser Compton scattering rays at the electron storage ring NewSUBARU

Hayakawa, Takehito; Miyamoto, Shuji*; Hayashi, Yukio; Kawase, Keigo*; Horikawa, Ken*; Chiba, Satoshi; Nakanishi, Kosuke*; Hashimoto, Hisanobu*; Ota, Takeshi*; Kando, Masaki; Mochizuki, Takayasu*; Kajino, Toshitaka*; Fujiwara, Mamoru

We report a half-life of the ground state of Re populated by the ReRe reaction with the laser Compton scattering -rays generated through relativistic engineering. The -rays are provided at the electron storage ring NewSUBARU. The previous experiment using deuteron-induced reactions has yielded a recommended half-life of the 3 ground state of Re to be 38.0 0.5 d, including a possible contribution from the 8 isomer ( = 169 8 d) of Re since the presence of the isomer was not known at that time. In contrast, the reaction has an 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.