Invariant-mass spectroscopy of the unbound nucleus 13Be
The unbound nucleus 13Be was investigated by means of invariant-mass method in the one-neutron removal reaction of 14Be at 69 MeV/nucleon. A p-wave resonance was observed at 0.51 MeV in the decay energy spectrum. The existence of the low-lying p state shows the quenching of the N = 8 shell gap.