K-hindered beta and gamma transition rates in deformed nuclei and the halflife of Ta-180(m)

摘要

K-hindered beta (beta) and gamma (gamma) transition rates in deformed nuclei around the mass number A = 180 are shown to be highly reduced due to the K selection rule. The nuclear matrix elements for the beta and gamma transitions are shown to be expressed as M= M0F Delta K-L with Delta K and L being the change of the K quantum number and the transition multi-polarity. On the basis of this experimental rule, the beta and gamma transition rates and the halflife of Ta-180(m), which are of great interest from astrophysics view points, are evaluated. The found K selection rule can be used to study nucleosynthesis rates associated with neutrino and photon interactions in deformed nuclei.