Fusion and breakup at the barrier with 11Be

The cross-section excitation functions for various neutron-evaporation channels have been measured in the 11,10,9 Be+ 209 Bi systems around the Coulomb barrier, for energies ranging from 35 to 70 MeV, in order to see any eventual effect from the expected breakup of the 11 Be unstable halo nucleus. Within the simplified reaction process considered, the data are consistent with a breakup of 11 Be at the top of the Coulomb barrier contributing to less than 25% to the total fusion cross-section; however contributions from other type of breakup mechanisms cannot be excluded.