Improvement of the gross theory of decay by inclusion of change in parity

Koura, Hiroyuki   ; Chiba, Satoshi*

An improvement on the single-particle structure is carried out to a global -decay model, the gross theory. The gross theory is based on a consideration of the sum rule of the intensity of the -decay transition by using the strength function. This model gives reasonable results of -decay rates and delayed neutron in the entire nuclear mass region. An attempt is made to improve the gross theory of nuclear -decay on consideration of the change of parity on the single-particle level of ground-state nuclei. In this treatment, the nuclear matrix elements are suppressed when the parity between single neutron and proton levels is different for the allowed transition. The assignment of parity is done by using the Woods-Saxon type single-particle potential. The discrepancies from experimental half-lives, which appeared in the vicinity on the magic number of neutrons and protons, are systematically improved in the nuclear mass region.