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

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. 1