  As a model of a neutron halo nucleus we consider a neutron bound to an inert
core by a zero range force. We study the breakup of this simple nucleus in the
Coulomb field of a target nucleus. In the post-form DWBA (or, in our simple
model CWBA (``Coulomb Wave Born Approximation'')) an analytic solution for the
T-matrix is known. We study limiting cases of this T-matrix. As it should be,
we recover the Born approximation for weak Coulomb fields (i.e., for the
relevant Coulomb parameters much smaller than 1). For strong Coulomb fields,
high beam energies, and scattering to the forward region we find a result which
is very similar to the Born result. It is only modified by a relative phase
(close to 0) between the two terms and a prefactor (close to 1). A similar
situation exists for bremsstrahlung emission. This formula can be related to
the first order semiclassical treatment of the electromagnetic dissociation.
Since our CWBA model contains the electromagnetic interaction between the core
and the target nucleus to all orders, this means that higher order effects
(including postacceleration effects) are small in the case of high beam
energies and forward scattering. Our model also predicts a scaling behavior of
the differential cross section, that is, different systems (with different
binding energies, beam energies and scattering angles) show the same dependence
on two variables x and y.
