Breakup Effect on the Reactions of 4;6He and 6Li

The breakup effect on the scattering and reaction of 4,6He+p,12C, 40Ca and 6Li+p at energies of 50–800 MeV/nucleon has been studied in the framework of the eikonal approxi-mation. The eikonal phase-shift functions have been calculated completely employing Monte Carlo integration. Realistic 6-nucleon wave functions for the 6He and 6Li nuclei have been used. The dynamic polarization potentials have been determined. We find that the breakup effect is minimal at an incident energy of 200 MeV/nucleon. At this energy, the imaginary part of the polarization potential changes sign (negative to positive with increasing energy). The real part of the polarization potential also changes sign (repulsive to attractive) around 400 MeV/nucleon. This sign change depends neither on the target nor the projectile. It de-pends only on the ratio of the real to the imaginary parts of the underlying nucleon-nucleon (or nucleon-target) potential. The breakup effect is stronger in 6He than in 6Li. Halo nuclei are a special case of radioactive beams for which the last nucleons are very weakly bound, with separation energies of the order of 0.5 MeV or less, and in a state of low angular momentum (l=0,1). The small separation energ