Cross-shell excitations near the island of inversion: Structure of 30Mg

Excited states in Mg-30 have been populated to similar to 6 (h) over bar and 5MeV excitation energy with the C-14(O-18, 2p) reaction. Firm spin assignments for states with J > 2 (h) over bar h have been made in this nucleus. The level scheme is compared to shell-model calculations using the Universal sd effective interaction and the Monte Carlo shell model method. Calculations employing a full sd model space fail to reproduce the observed levels. The results indicate that excitations across the N = 20 gap are required at relatively low excitation energy to achieve a description of the data. The incorporation of the f(7/2) and p(3/2) orbitals into the model space gives improved results but indicate the need for further refinement of the models to reproduce the observed spectra.