Abstract

Thick neutron skins (∼ 0.9 fm) have been verified for the first time in 6He and 8He nuclei from a combined analysis of the interaction and the fragmentation cross sections of 4,6,8He incident reactions at 800A MeV. A relativistic mean field (RMF) model was applied to 6He and 8He nuclei and shown to reproduce the neutron skin thicknesses very well. It is also shown that the RMF model predicts a gross linear dependence of the neutron skin thickness on the difference between the proton and the neutron Fermi energy in a wide range of nuclei. Possible observations of thick neutron skins in other nuclei, in particular in Na isotopes, are also discussed.