Fusion Excitation Functions at Near- and sub-Coulomb Barrier for Symmetric and Asymmetric Medium-Mass Systems

摘要

During the last few years, the study of heavy ion fusion reactions at energies well below the s-wave interaction barrier has attracted considerable theoretical and experimental interest. The observed cross sections are significantly larger than predicted by conventional one-dimensional barrier penetration models. The precise mechanism leading to sub-barrier fusion cross sections enhancement is still to be understood. We have undertaken a series of measurements of the fusion cross section for the asymmetric systems sup 12 C + sup 46 Ti, sup 48 Ti, sup 50 Ti, sup 18 O + sup 44 Ca and symmetric systems sup 28 Si, sup 30 Si + sup 30 Si over an energy range extending from approximately 0.6 time the Coulomb barrier, Bsub(C), to approximately 2Bsub(C), forming each time the same compound nucleus by two different entrance channels.