Role of intruder configurations in 26,28Ne and 30,32Mg

The energies and reduced transition probabilities B(E2;0g.s.+→2+) for the lowest Jπ=2+ excited states in the neutron-rich radioactive isotopes 26,28Ne and 30,32Mg were measured via intermediate energy Coulomb excitation. The data suggest that the interaction between coexisting 0ℏω (normal) and 2ℏω (intruder) configurations significantly perturbs the energy of the 21+ state in 28Ne, while the data on 26Ne and 30Mg can be well understood in the context of 0ℏω configurations alone. Nilsson model calculations suggest that if these nuclei have static axially symmetric deformations, they are prolate.