Role of nuclear structure degrees of freedom and energy dependent interaction potential in sub-barrier fusion dynamics

Abstract

The role of the nuclear structure degrees of freedom associated with the colliding nuclei and the energy dependence in the nucleus–nucleus interaction potential in fusion dynamics of various projectiles (16O, 27Al and 37Cl) with the Ge-isotopes (74,76Ge) has been investigated. Fusion cross-sections obtained through energy dependent interaction potential (EDWSP model) and coupled channel theory show quite similar behavior in near and above barrier energy regions. In coupled channel view, the couplings to inelastic surface excitations associated with the fusing nuclei results in large fusion enhancement at sub-barrier energies. The consideration of spherical shape for targets (74,76Ge-isotopes) along with their relevant internal structure degrees of freedom in coupled channel approach is sufficient to get a good description to observed fusion enhancement of the studied reactions. In contrast, the energy dependent interaction potential modifies the barrier profile of interaction barrier and subsequently reduces the effective fusion barrier between the colliding systems, henceforth, predicts substantially large fusion enhancement at below barrier energies in comparison to the expectations of the one dimensional barrier penetration model. Furthermore, χ2-analysis and the ratio plots σThσExp for outcomes of the EDWSP model suggested that the model calculations provide a consistent fit to fusion data within 10%. For the chosen reactions, only at 6 fusion data points out of 75 fusion data points does the deviation exceed 5% while 69 fusion data points lie within 5% and hence, the EDWSP model reasonably explained the above barrier fusion data within 5% with a probability more than 90%.