Abstract
The recently confirmed neutron-shell closure at has been investigated for the first time below the magic proton number with mass measurements of the exotic isotopes , the latter being the shortest-lived nuclide investigated at the online mass spectrometer ISOLTRAP. The resulting two-neutron separation energies reveal a 3 MeV shell gap at , slightly lower than for , highlighting the doubly magic nature of this nuclide. Skyrme-Hartree-Fock-Bogoliubov and ab initio Gorkov-Green function calculations are challenged by the new measurements but reproduce qualitatively the observed shell effect.
- Received 31 December 2014
DOI:https://doi.org/10.1103/PhysRevLett.114.202501
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Published by the American Physical Society