  Nuclear and Coulomb breakup of halo nuclei have been treated often as
incoherent processes and structure information have been extracted from their
study. The aim of this paper is to clarify whether interference effects and
Coulomb-nuclear couplings are important and how they could modify the simple
picture previously used.
  We calculate the neutron angular and energy distributions by using first
order perturbation theory for the Coulomb amplitude and an eikonal approach for
the nuclear breakup. This allows for a simple physical interpretation of the
results which are mostly analytical. Our formalism includes the effect of the
nuclear distortion of the neutron wave function on the Coulomb amplitude. This
leads to a Coulomb-nuclear coupling term derived here for the first time which
gives a small contribution for light targets but is of the same order of
magnitude as nuclear breakup for heavy targets. The overall interference is
constructive for light to medium targets and destructive for heavy targets.
Thus it appears that Coulomb breakup experiments need to be analyzed with more
accurate models than those used so far.
