Optical model analysis of elastic scattering and fusion in reactions with weakly bound projectiles around the Coulomb barrier

A simultaneous Distorted Wave Born Approximation calculation of elastic scattering, fusion and breakup cross sections for energies around the Coulomb barrier is presented for reactions involving weakly bound projectiles on a medium size target. A Woods-Saxon optical potential is used, for which the imaginary part is split into a volume part WF which is responsible for fusion reactions and a surface part WDR which accounts for direct reactions. Energy dependent forms for WF and WDR are then extracted from recent data. By the use of the dispersion relation, the corresponding real polarization potentials VF(E) and VDR(E) are also determined. As a result, a new type of anomaly is present, the so called Breaukup Threshold Anomaly.