Disappearance of the N=14 shell

An excited state of N-22 unbound with respect to neutron emission was observed in a stripping reaction from a 85 MeV/nucleon F-26 beam. The observed decay energy of 650(50) keV places the level, which is interpreted to be the first 3(-) state, at an excitation energy of 1.93(22) MeV. Together with the previously measured bound states of N-22, reduction of the N=14 shell gap compared to less neutron-rich nitrogen isotopes at the neutron dripline is observed. Based on the magnitude of the reduction of the shell gap for N-22, a disappearance of the gap and even a level inversion of the nu 1s(1/2) and the nu 0d(5/2) levels in the neutron-unbound nucleus C-21 seems likely.