Abstract
The and isomers of the nuclei are investigated in the shell-model framework. We derive an extended seniority reduction formula for the relevant transition strengths. Based on the extended formula, as well as on the approximate degeneracy among the and orbits, we argue that the data require the core excitation. The energy levels of both parities and the values are simultaneously reproduced by a multi- shell-model calculation with the modified surface-delta interaction, if the excitations from to are taken into account.
- Received 6 June 2000
DOI:https://doi.org/10.1103/PhysRevC.62.054304
©2000 American Physical Society