Abstract
A physical prescription to improve the accuracy of few-body Glauber model calculations of reactions involving loosely-bound projectiles is presented, in which the eikonal phase shift function of each projectile constituent is modified to account for curvature of its trajectory. This involves replacing the eikonal phase by the Wentzel-Kramers-Brillouin (WKB) phase, and including Rosen and Yennie and Wallace corrections. Non-eikonal effects due to both nuclear and Coulomb interactions are treated on an equal footing. The proposed method is assessed quantitatively by comparison with full quantum mechanical calculations of d + 12 C and 11Be+12C elastic scattering. The deuteron is treated as a three-body 1p+1n+ target problem. In the case of 11Be it is treated as a 10Be+1n+target problem. Both are investigated at low and medium energies. Calculated differential cross section angular distributions which include the non-eikonal modifications are shown to be accurate to larger scattering angles, and for lower incident projectile energies. A further refinement is then introduced whereby the analytic continuation of the two-body scattering S-matrices replace the corrected phases. Each cluster-target eikonal phase shift is replaced by the continuation of the corresponding exact partial wave phase shift to non-integer angular momenta. Comparisons with fully quantum mechanical calculations for two-body and three-body projectiles, show that this yields an accurate practical alternative to few-body adiabatic model calculations. Calculations are shown to be accurate for projectile energies as low as 10.0 MeV/A at which the eikonal approximation is no longer reliable. Our results demonstrate a real improvement in calculated cross sections when using more realistic phase shifts rather than eikonal phase shifts derived from the same potentials. For the systems under study, the significance of the overlap in the incident projectile cluster-target potentials is considered to gauge the magnitude of these effects which were found to be insignificant.