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 ${}^{19}\mathrm{C}$ at $67A\mathrm{MeV}$ and of ${}^{11}\mathrm{Be}$ 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.

• Received 16 January 2001

DOI:https://doi.org/10.1103/PhysRevC.64.024601