Angular distributions of the elastic, inelastic, and breakup cross sections of the halo nucleus 11Be on 197Au 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 11Be 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(E1) distribution in 11Be, and the reaction mechanism is sensitive to the entanglement of core and halo degrees of freedom in 11Be.
This work has been supported by the Spanish Ministerio de Economia y Competitividad and FEDER, under the Projects No. FPA2015-64969-P, No. FIS2014-53448-C2-1-P, No. FPA2013-47327-c02-01-R, No. FPA2012-32443, No. FIS2013-41994-P, and Consolider CPAN CSD2007-00042; the EUROCORES Project No. EUI-2009-04162; the European Unions Horizon 2020 research and innovation program under Grant Agreement No. 654002; the Helmholtz Association (HGT) through the Nuclear Astrophysics Virtual Institute (VH-VI-417); ATI Sistemas; The Natural Sciences and Engineering Research Council of Canada; The Canada Foundation for Innovation; and the British Columbia Knowledge Development Fund. TRIUMF receives federal funding via a contribution agreement through the National Research Council of Canada. The research leading to these results has received funding from the European Commission, Seventh Framework Program (FP7/2007-2013) under Grant Agreement No. 600376. J. A. L. is a Marie Curie Piscopia fellow at the University of Padova. O. S. K. acknowledges support from the Villum Foundation.