Abstract
A long-lived isomer, , has been discovered at 643.4(1) keV in the weakly bound nucleus. It was populated at Grand Accélérateur National d’Ions Lourds in the fragmentation of a beam. It decays by an internal transition to the ground state [82(14)%], by decay to , or -delayed neutron emission to . From the -decay studies of the and states, new excited states have been discovered in . Gathering the measured binding energies of the multiplet in , we find that the proton-neutron effective force used in shell-model calculations should be reduced to properly account for the weak binding of . Microscopic coupled cluster theory calculations using interactions derived from chiral effective field theory are in very good agreement with the energy of the low-lying , , states in . Including three-body forces and coupling to the continuum effects improve the agreement between experiment and theory as compared to the use of two-body forces only.
- Received 29 November 2012
DOI:https://doi.org/10.1103/PhysRevLett.110.082502
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