The beta decay of the exotic 30Ne (N=20) is reported. For the first time, the
low-energy level structure of the N=19, 30Na (Tz = 4), is obtained from
beta-delayed gamma spectroscopy using fragment-beta-gamma-gamma coincidences.
The level structure clearly displays "inversion", i.e., intruder states with
mainly 2p2h configurations displacing the normal states to higher excitation
energies. The good agreement in excitation energies and the weak and
electromagnetic decay patterns with Monte Carlo Shell Model calculations with
the SDPF-M interaction in the sdpf valence space illustrates the small d3/2 -
f7/2 shell gap. The relative position of the "normal dominant" and "intruder
dominant" excited states provides valuable information to understand better the
N=20 shell gap.Comment: 4 pages, 5 figure
