FUSION AND BREAKUP AT THE BARRIER WITH BE-11

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