Tunneling in high- isomeric decays

Shizuma, Toshiyuki; Shimizu, Yoshifumi*; Hayakawa, Takehito

We have systematically investigated the highly -forbidden transitions observed in the Hf, W and Os region, using the -tunneling model in which low- and high- states interact through a process of the quantum tunneling. In the present study, we have analyzed -forbidden transitions recently observed. The measured hindrance factors are compared with the values calculated using the -tunneling model. We have also investigated isotope dependences of tunneling probabilities particularly for neutron-rich nuclei.