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Resonances in the unbound nucleus 11 N have been studied, using the resonance scattering reaction 10 Cϩp. The data give evidence for three states above the 10 Cϩp threshold with energies 1.30, 2.04, and 3.72 MeV. These states can be interpreted, in a potential-model analysis, as the ground state and the first two excited states with spin-parity 1/2 ϩ , 1/2 Ϫ , and 5/2 ϩ arising from the shell-model orbitals 1s 1/2 , 0p 1/2 , and 0d 5/2. A narrow state superposed on a broad structure found at higher energy could be interpreted as the mirror state of the 3/2 Ϫ in 11 Be shifted down in energy. This shift would suggest a large radius of the potential. ͓S0556-2813͑96͒50110-X͔

Excitation functions for 18 Oϩ␣ elastic scattering were measured by a method using inverse kinematics and a thick gas target. An analysis of the data corresponding to the excitation energy regions of 11.8 -13.7 MeV and 19.0-22.0 MeV in 22 Ne was carried out. A surprising splitting of 1 Ϫ , 3 Ϫ , 7 Ϫ , and 9 Ϫ ␣-cluster levels into doublets was found in 22 Ne.

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

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