Observation of abnormally large radii of nuclei in excited states in the vicinity of neutron thresholds

Abstract

Differential cross sections for inelastic scattering leading to the excitation of some nuclear states situated near neutron-emission thresholds were analyzed. With the aid of a modified diffraction model, abnormally large radii were found for the 1/2 1 + state of the 13C nucleus at 3.09 MeV, for the first levels of positive-parity rotational bands in the 9Be (1/2+ level at 1.68 MeV and 5/2+ level at 3.05 MeV) and 11Be (5/2+ level at 1.78 MeV and 3/2+ level at 3.41 MeV) nuclei, and for the 2 1 + state of the 14Be nucleus at 1.54 MeV and 1 1 − state of the 12Be nucleus at 2.7 MeV. All of these states possess signatures typical of neutron halos.