Intruder configurations in the ground state of 30 Ne

Abstract We report on the first detailed study of intruder configurations in the ground state of 30 Ne by means of the 12 C( 30 Ne,  29 Ne+ γ )X one-neutron knockout reaction at 228 MeV/nucleon. Using a combined analysis of individual parallel momentum distributions and partial cross sections we find: (a) comparable p - and d -wave removal strength to 29 Ne final states with excitation energies below 200 keV, and (b) significant p -wave removal strength to the 620 keV state of 29 Ne, and (c) no evidence for f -wave intruder strength leading to bound 29 Ne final states. The SDPF-U-MIX shell model calculation in the s d – p f model space provides a better overall agreement with the measured energy levels of 29 Ne and the fp -intruder amplitudes in 30 Ne than the SDPF-M prediction, suggesting that the refinement of the s d – p f cross shell interaction and extension of the model space to include the 2 p 1 / 2 and 1 f 5 / 2 levels are important for understanding the island of inversion.