Effect of Proximity Force on Potential Barrier in Fusion Reaction

Abstract：

The macroscopic deformed potential energies for fusion reactions are determined within a generalized liquid drop model (GLDM) which includes the volume—,surface,and Coulomb energies,the proximity effects,the mass asymmetry,and an accurate nuclear radius. In ordinary fission studies,it is assumed that the surface and Coulomb energies control the hight and width of the barrier. The surface energy E_S takes into account only the effect of the surface tension force and does not include the contribution of the attractive nuclear forces between surfaces in regard to the neck or the gap between the nascent fragments. The nuclear proximity energy is adopted to take into account these additional surface effects in general liquid drop model. At the contact point,the proximity energy reaches maximum while it decreases both sides till to zero. The proximity energy decreases the barrier height by several MeV and moves the position of the barrier top forward,which corresponds to two separated fragments in unstable equilibrium by the balance between the attractive nuclear proximity force and the repulsive Coulomb force in the GDLM. It turns out that a wide macroscopic potential pocket in fusion process is formed due to proximity energy and appears at large deformation. This behavior does not appear at the barrier for the fusion reaction of light nucleus nucleus collision.