FUSION BARRIER DISTRIBUTIONS IN SYSTEMS WITH FINITE EXCITATION-ENERGY

An eigenchannel approach to heavy-ion fusion reactions is exact only w hen the excitation energy of the intrinsic motion is zero. In order to take into account effects of finite excitation energy, we introduce a n energy dependence to weight factors in the eigenchannel approximatio n. Using the two channel problem, we show that the weight factors are slowly changing functions of incident energy. This suggests that the c oncept of the fusion barrier distribution still holds to a good approx imation even when the excitation energy of the intrinsic motion is fin ite. A transition to the adiabatic tunneling, where the coupling leads to a static potential renormalization, is also discussed.