  We calculate the nuclear induced breakup of Be11 and B8 using a more
realistic treatment of the diffraction and stripping processes than in previous
work. The breakup is treated in the eikonal approximation with a profile
function calculated from a realistic optical potential at low energies and from
free nucleon-nucleon cross sections at high energies. This treatment gives a
good description of measured breakup cross sections, as well as the
longitudinal momentum distribution of the core-like fragments, which is
narrower than predicted in the transparent limit. The real part of the
potential is found to be significant and enhances the diffractive breakup at
low energies.
