Noneikonal calculations for few-body projectiles

Calculations which improve upon the eikonal model description of the scatte ring of loosely bound n-cluster composite nuclei at low and medium energies are studied. Each cluster-target eikonal phase shift is replaced by the co ntinuation of the corresponding exact partial wave phase shift to nonintege r angular momenta. Comparisons with fully quantum mechanical calculations f or two-body projectiles show that this yields an accurate practical alterna tive to few-body adiabatic model calculations. Calculations are shown to be accurate fur projectile energies as low as 10 MeV/nucleon at which the eik onal approximation is no longer reliable. [S0556-2813(99)04703-2].