Higher order effects in electromagnetic dissociation of neutron halo nuclei

We investigate higher order effects in electromagnetic excitation of neutron halo nuclei using a zero-range model for the neutron-core interaction. In the sudden (or Glauber) approximation all orders in the target-core electromagnetic interaction are taken into account. Small deviations from the sudden approximation are readily calculated. We obtain very simple analytical results and scaling laws for the next-to-leading order effects, which have a simple physical interpretation. For intermediate energy electromagnetic dissociation, higher order effects are generally small. We apply our model to Coulomb dissociation of ¹⁹C at 67A MeV and of ¹¹Be at 72A MeV. The analytical results are compared to numerical results from the integration of the time-dependent Schrödinger equation. Good agreement is obtained. We conclude that higher order electromagnetic effects are well under control.