Fusion of Sn-124,Sn-132 with Ca-40,Ca-48

Fusion excitation functions for the reactions of Sn-124,Sn-132 with Ca-40,Ca-48 were measured at energies near and below the Coulomb barrier. Weak sub-barrier fusion enhancement accounted for by coupling to the first 2(+) and 3(-) states in the target and projectile was observed for Sn-124,Sn-132 + Ca-48. However, the Sn-124,Sn-132 + Ca-40 fusion cross sections are very strongly enhanced below the barrier and this difference survives even after correcting for trivial size effects. Although the enhancement appears to be related to the existence of large positive Q values for neutron transfer reactions, it is not proportional to the magnitudes of those Q values, which are much larger for Sn-132 + Ca-40 than for Sn-124 + Ca-40.