Disappearence of the N=14 Shell

The decay-energy spectrum of $^{22}$N was measured in a neutron-fragment coincidence experiment at the National Superconducting Cyclotron Laboratory at MSU. An excited state of $^{22}$N, 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 $^{26}$F 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 $^{22}$N, 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 $\nu1s_{1/2}$ and the $\nu0d_{5/2}$ levels in the neutron-unbound nucleus $^{21}$C.