Disappearence of the N=14 Shell
Abstract
The decay-energy spectrum of ^22N was measured in a neutron-fragment coincidence experiment at the National Superconducting Cyclotron Laboratory at MSU. An excited state of ^22N, unbound with respect to neutron emission measured by the Modular Neutron Array (MoNA), was observed in a stripping reaction from a secondary 85 MeV/u ^26F beam. The observed decay energy of 650(50) keV places the state, which is interpreted to be the first 3^- level, at an excitation energy of 1.93(22) MeV. Together with the previously measured bound states of ^22N, the reduction of the N = 14 shell gap at the neutron dripline is observed. The magnitude of the reduction of the shell gap indicates the disappearance of the gap and even a possible reoccurrence of the inversion of the ν1s1/2 and the ν0d5/2 levels in the neutron-unbound nucleus ^21C.
- Publication:
-
APS Meeting Abstracts
- Pub Date:
- October 2009
- Bibcode:
- 2009APS..HAW.LL003S