Unexpected results in neutron-rich radioactive beams induced fusion

The fission-fragment beams at HRIBF provide a unique opportunity for studying the mechanisms of fusion involving nuclei with large neutron excess. To explore the role of transfer couplings, fusion excitation functions have been measured using neutron-rich radioactive ¹³²Sn beams incident on ⁴⁰Ca and ⁵⁸Ni targets. The sub-barrier fusion enhancement for ¹³² Sn+⁴⁰Ca is larger than that for ¹³²Sn+⁵⁸Ni although the neutron transfer Q-values are similar for the two reactions. The fusion excitation function for ⁴⁶Ti+¹²⁴Sn has been measured in an attempt to resolve the differences observed in ¹³²Sn+⁴⁰Ca and ¹³²Sn+⁵⁸Ni.