Exact and approximate postform distorted-wave Born approximation amplitudes for the Coulomb breakup of neutron halo nuclei

The Coulomb breakup of neutron halo nuclei is considered within the framework of the postform distorted-wave Born approximation (DWBA). The quality of commonly used additional approximations to the DWBA theory is investigated by comparing the approximate with the exact DWBA calculations. The exact DWBA amplitude is expressed in momentum space as a three-dimensional integral and evaluated numerically. Calculations are presented for the Coulomb breakup of deuteron and ¹¹Be at very forward angles at the beam energy of ∼70 MeV/nucleon. The factorization approximation to the DWBA amplitude is studied and found to be suspected.