Comparison of 120Sn (6He,6He)120Sn and 120Sn (α,α)120Sn elastic scattering and signatures of the 6He neutron halo in the optical potential

Abstract

Cross sections of 120Sn(α,α)120Sn elastic scattering have been extracted from the α-particle-beam contamination of a recent 120Sn(6He,6He)120Sn experiment. Both reactions are analyzed using systematic double-folding potentials in the real part and smoothly varying Woods-Saxon potentials in the imaginary part. The potential extracted from the 120Sn(6He,6He)120Sn data may be used as the basis for the construction of a simple global 6He optical potential. The comparison of the 6He and α data shows that the halo nature of the 6He nucleus leads to a clear signature in the reflexion coefficients ηL: The relevant angular momenta L with ηL ≫ 0 and ηL ≪ 1 are shifted to larger L with a broader distribution. This signature is not present in the α-scattering data and can thus be used as a new criterion for the definition of a halo nucleus.