Spectroscopy of Na 28: Shell evolution toward the drip line

Lepailleur, A. and Wimmer, K. and Mutschler, A. and Sorlin, O. and Thomas, J. C. and Kunné Sohler, Dorottya (2015) Spectroscopy of Na 28: Shell evolution toward the drip line. PHYSICAL REVIEW C, 92 (5). ISSN 2469-9985

Preview

Text 1503.08568.pdf Available under License Creative Commons Attribution. Download (907kB) | Preview

Abstract

Excited states in 28Na have been studied using the β-decay of implanted 28Ne ions at GANIL/LISE as well as the in-beam γ-ray spectroscopy at the NSCL/S800 facility. New states of positive (Jπ=3,4+) and negative (Jπ=1-5−) parity are proposed. The former arise from the coupling between 0d5/2 protons and a 0d3/2 neutron, while the latter are due to couplings with 1p3/2 or 0f7/2 neutrons. While the relative energies between the Jπ=1-4+ states are well reproduced with the USDA interaction in the N=17 isotones, a progressive shift in the ground state binding energy (by about 500 keV) is observed between 26F and 30Al. This points to a possible change in the proton-neutron 0d5/2-0d3/2 effective interaction when moving from stability to the drip line. The presence of Jπ=1- 4 − negative parity states around 1.5 MeV as well as of a candidate for a Jπ=5− state around 2.5 MeV give further support to the collapse of the N=20 gap and to the inversion between the 0f7/2 and 1p3/2 levels below Z=12. These features are discussed in the framework of Shell Model and EDF calculations, leading to predicted negative parity states in the low energy spectra of the 26F and 25O nuclei.

Actions (login required)

Edit Item