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.
@article{arxiv.nucl-ex/0703015,
title = {Competition between normal and intruder states inside the "Island of Inversion"},
author = {Vandana Tripathi and S. L. Tabor and P. F. Mantica and Y. Utsuno and P. Bender and J. Cook and C. R. Hoffman and Sangjin Lee and T. Otsuka and J. Pereira and M. Perry and K. Pepper and J. Pinter and J. Stoker and A. Volya and D. Weisshaar},
journal= {arXiv preprint arXiv:nucl-ex/0703015},
year = {2009}
}