Nuclear collectivity and its role on beta-decay

Minato, Futoshi   

The nuclear vibration and rotation are strongly related with excited states. They can be described by an idea of collective motion, which indicates that nucleons inside a nucleus coherently contribute the motion. We call its character collectivity. Besides the vibration and rotation, the collectivity plays an important role in beta-decay of a nucleus. Due to the collectivity, beta-decay shows a different characteristic from that of free neutron. We investigate the beta-decay of neutron-rich unstable nuclei within the framework of the random-phase-approximation. We find that the effect of collectivity on the beta-decay half-lives is more important and complex than we have ever known. We also introduce several applications of the work of beta-decay to other research fields.