Crossing the dripline to N-11 using elastic resonance scattering

Abstract

The level structure of the unbound nucleus N-11 has been studied by C-10+p elastic resonance scattering in inverse geometry with the LISE3 spectrometer at GANIL, using a C-10 beam with an energy of 9.0 MeV/ nucleon. An additional measurement was done at the A1200 spectrometer at MSU. The excitation function above the C-10+p threshold has been determined up to 5 MeV. A potential-model analysis revealed three resonance states at energies 1.27(-0.05)(+0.18) MeV (Γ = 1.44 ± 0.2 MeV), 2.01(-0.05)(+0.15) MeV (Γ = 0.84 ± 0.2 MeV), and 3.75 ± 0.05 MeV (Γ = 0.60 ± 0.05 MeV) with the spin-parity assignments I(π)=1/2(+),1/2(-),5/2(+), respectively. Hence, N-11 is shown to have a ground state parity inversion completely analogous to its mirror partner Be-11. A narrow resonance in the excitation function at 4.33 ± 0.05 MeV was also observed and assigned spin parity 3/2(-).