The Effects of Deformed Projectile in Threshold Anomaly and Fusion Reaction for ¹⁹F+²⁰⁸Pb System

Abstract

Angular distributions of elastic scatterings for ¹⁹F+²⁰⁸Pb system have been measured at six energies around the Coulomb barrier. It is found that the real and imaginary potentials show pronounced energy dependence in terms of the phenomenological optical model analysis. The real parts of potentials extracted from the fusion data are similar to those from the elastic data. A comparison with the neighbouring systems of ¹⁶O+²⁰⁸Pb and ¹⁶O+²⁰⁹Bi reveals that the ¹⁹F deformations play an important role in the fusion reaction. Based on the deformed and energy dependent barrier penetration model, the calculated fusion cross sections and mean-square spin distribution agree with the experimental data well. Moreover, it is indicated that the enhancement of fusion cross sections attributes to the dynamic polarization effects around the barrier, and to the static deformation effects further below the barrier.