Lifetime measurements of long-lived isomers in Gd using a total absorption detector

Asai, Masato; Hayashi, Hiroaki*; Osa, Akihiko; Sato, Tetsuya; Otokawa, Yoshinori; Nagae, Daisuke; Tsukada, Kazuaki; Miyashita, Yuji*; Ouchi, Hiroyuki*; Izumi, Sayaka*; et al.

no journal, , 

We have developed a new method to measure lifetime of long-lived isomers populated through the decay, using a total absorption detector. Using this method, we have determined lifetime of the K isomers in Gd and Gd for the first time. The short-lived neutron-rich nuclei Eu and Eu were produced and mass-separated by the on-line isotope separator (ISOL) at JAEA tandem accelerator facility. Beta- and rays emitted by the decay of Eu were total-absorbed by the detector, and all the events were recorded with time stamps. This method enabled us to determine lifetime of the isomers with more than 100-s lifetime.