Spectroscopy of 9Be and observation of neutron halo structure in the states of positive parity rotational band

The differential cross sections of the 9 Be + α inelastic scattering at 30 MeV were measured at the tandem of Tsukuba University. All the known states of 9 Be up to energies ~ 12 MeV were observed and decomposed into three rotational bands, each of them having a cluster structure consisting of a 8 Be 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.