Scattering of the halo nucleus 11Be on 197Au at energies around the Coulomb barrier

Angular distributions of the elastic, inelastic, and breakup cross sections of the halo nucleus 11 Be on 197 Au were measured at energies below (𝐸lab =31.9  MeV) and around (39.6 MeV) the Coulomb barrier. These three channels were unambiguously separated for the first time for reactions of 11 Be on a high-𝑍 target at low energies. The experiment was performed at TRIUMF (Vancouver, Canada). The differential cross sections were compared with three different calculations: semiclassical, inert-core continuum-coupled-channels and continuum-coupled-channels ones with including core deformation. These results show conclusively that the elastic and inelastic differential cross sections can only be accounted for if core-excited admixtures are taken into account. The cross sections for these channels strongly depend on the ℬ⁡(𝐸⁢1) distribution in 11 Be , and the reaction mechanism is sensitive to the entanglement of core and halo degrees of freedom in 11 Be .