Quantum surface friction model for fusion reactions around the Coulomb barrier*

For the description of heavy-ion fusion reactions at energies above the Coulomb barrier, the classical trajectory calculation with a frictional force has been developed. The necessity of a frictional force was suggested by the experimental fact that a large amount of energy loss takes place in scattering experiments. Although the classical friction model can nicely describe above barrier fusion reactions, it cannot be applied to fusion reactions at energies below the Coulomb barrier, where fusion reactions take place only by quantum tunneling.

In order to achieve a unified description of sub- and above barrier fusion reactions, we focus on a quantum friction model invented by M.D. Kostin. With that model, we carry out quantum mechanical calculation of fusion reactions with friction. For the form of a frictional force, we employ the surface friction model, which is known to be one of successful models of classical trajectory calculation. In the presentation, we shall show that fusion cross sections with the quantum friction are in between fusion cross sections without friction and that of the classical trajectory calculation, and they provide better agreement with experimental data.