Abstract
Delayed -ray cascades, originating from the decay of isomeric states, in the very neutron-rich, semimagic isotopes Sn have been observed following the projectile fission of a U beam at RIBF, RIKEN. The wave functions of these isomeric states are proposed to be predominantly a fully aligned pair of neutrons. Shell-model calculations, performed using a realistic effective interaction, reproduce well the energies of the excited states of these nuclei and the measured transition rates, with the exception of the rate of Sn, which deviates from a simple seniority scheme. Empirically reducing the orbit matrix elements produces a state with almost equal seniority 2 and 4 components, correctly reproducing the experimental rate of Sn. These data provide a key benchmark for shell-model interactions far from stability.
- Received 14 April 2014
DOI:https://doi.org/10.1103/PhysRevLett.113.132502
© 2014 American Physical Society