The effects of deformed projectile in threshold anomaly and fusion reaction

Abstract

Angular distributions of elastic scatterings for 19 F + 208 Pb 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 16 O + 208 Pb and 16 O + 209 Bi reveals that the 19 F 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.