Interaction at the barrier with unstable/loosely bound projectiles

The fusion cross sections above the barrier in the unstable/loosely bound systems 9,10,11Be+209Bi and 6,7Li+12C, 9Be give indication of break-up contributions around 10-30% in agreement with the results from 11Li + silicon. Below the barrier the preliminary data of the two systems 9,11Be+209Bi show similar cross sections at variance with theoretical predictions; this could be tentatively attributed to break-up effects in 9Be stronger than expected. The 9,11Be+238U low-statistics data seem to confirm these facts. These new data should be confirmed and set in motion improved theoretical calculations. (author)