The differential cross sections of the inelastic scattering leading to the excitation of short-lived states in the stable ${}^{13}$C and ${}^9$Be nuclei as well as the radioactive ${}^{11}$Be nucleus have been analyzed. Signatures of neutron halos in the excited states located close to the neutron emission thresholds have been investigated by applying a recently developed modified diffraction model. The abnormally large rms radius was identified for the 3.089-MeV $1/2^{+}$ state of ${}^{13}$C. Significantly enlarged diffraction radii were found for the 1.68-MeV $1/2^{+}$ and the 3.05-MeV $5/2^{+}$ states of ${}^9$Be. The analysis of the diffraction radii of the weakly bound radioactive ${}^{11}$Be nuclei have shown that the 1.78-MeV $5/2^{+}$ and 3.41-MeV $3/2^{+}$ states in ${}^{11}$Be have the same diffraction radii as the $1/2^{+}$ ground state, which is known as the best example of a state with one-neutron halo. DOI: http://dx.doi.org/10.1103/PhysRevC.84.054601 ©2011 American Physical Society

EPJ Web of Conferences, open-access proceedings in physics and related sciences

EPJ Web of Conferences, open-access proceedings in physics and related sciences

The differential cross sections of the 9Be + α inelastic scattering at 30 MeV were measured at the tandem of Tsukuba University. All the known states of 9Be up to energies ~ 12 MeV were observed and decomposed into three rotational bands, each of them having a cluster structure consisting of a 8Be core plus a valence neutron in one of the sub-shells: p3/2− , s1/2+ and p1/2−. Existence of a neutron halo in the positive parity states was confirmed.

A method for determining the radii of excited states of nuclei by means of (³He, t) charge-exchange reactions was proposed. Two versions of a comparison of differential cross sections for (³He, t) reactions were considered. The first relies on a comparison with cross sections for inelastic-scattering processes leading to the formation of isobaric analog states, while the second involves (³He, t) reactions leading to the production of the ground state. The two versions in question yield similar results and make it possible to determine the radius of the first excited state of the ¹³N nucleus. This state has the excitation energy of E* = 2.37 MeV, lying above the proton-emission threshold. The resulting radius proved to be enhanced in relation to the ground state and is close to the radius of the 3.09-MeV isobaric analog state of the ¹³С nucleus, which has a neutron halo. This permitted drawing the conclusion that the ¹³N nucleus in the 2.37-MeV state has a proton halo. The possibility of revealing a proton halo in other states of light nuclei is considered.