Observation of the N-11 ground state

The ground state of the proton-rich, unbound nucleus N-11 was observed, tog ether with six excited states using the multinucleon transfer reaction B-10 (N-14, B-13)N-11 at 30A MeV incident energy at Grand Accelerateur National d'Ions Lourds. Levels of N-11 are observed as well defined resonances in th e spectrum of the B-13 ejectiles. They are localized at 1.63(5), 2.16(5), 3 .06(8), 3.61(5), 4.33(5), 5.98(10), and 6.54(10) MeV above the C-10 + p thr eshold. The ground-state resonance has a mass excess of 24.618(50) MeV; the experimental width is smaller than theoretical predictions.