Abstract
The multipolarities of the main transitions deexciting yrast isomers in have been measured using conversion electron spectroscopy with pulsed beams. The enhanced character of the 407 keV transition from the isomer is confirmed and an independent value obtained for its lifetime. A new measurement of the properties of the 440 keV decay from the corresponding state in has resulted in the identification of a new branch and a significantly different lifetime from that reported previously. The abnormally large strength of the to transitions in both and match those known in some light polonium isotopes, an effect which is suggested to be linked to a change in structure of the orbitals in the configuration when oblate deformation is established; the lowest proton Nilsson orbital changes from being predominantly of character at sphericity to a mixed parentage at oblate deformations, thus enabling an enhanced to octupole-coupled transition.
- Received 30 October 2000
DOI:https://doi.org/10.1103/PhysRevC.63.061302
©2001 American Physical Society