ADIABATIC QUANTUM TUNNELING IN HEAVY-ION SUBBARRIER FUSION

The measured fusion barrier distributions for Ca-40 + Os-192, Pt-194 s how significant features due to projectile excitation, while none are seen for O-16 + Sm-144. This conflict is reconciled using realistic co upled-channel calculations, which show that the higher excitation ener gy of the 3(-) state ill O-16 produces an adiabatic potential renormal ization, without affecting the structure in the barrier distribution. This result indicates that adiabatic effects restrict, in a natural wa y, the states which influence the shape of a fusion barrier distributi on.