Probing nuclear forces beyond the nuclear drip line: the cases of 16F and 15F: a tribute to Mahir Hussein

Abstract

The unbound proton-rich nuclei 16F and 15F are investigated experimentally and theoretically. Several experiments using the resonant elastic scattering method were performed at GANIL with radioactive beams to determine the properties of the low lying states of these nuclei. Strong asymmetry between 16F–16N and 15F–15C mirror nuclei is observed. The strength of the nucleon- nucleon effective interaction involving the loosely bound proton in the s1 / 2 orbit is significantly modified with respect to their mirror nuclei 16N and 15C. The reduction of the effective interaction is estimated by calculating the interaction energies with a schematic zero-range force. It is found that, after correcting for the effects due to changes in the radial distribution of the single-particle wave functions, the mirror symmetry of the n- p interaction is preserved between 16F and 16N, while a difference of 63% is measured between the p- p versus n- n interactions in the second excited state of 15F and 15C nuclei. Several explanations are proposed. © 2021, The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature.