This paper is concerned with the use of a microscopic optical potential in the description of the final state interaction of a breakup neutron from a halo projectile such as ${}^{11}\mathrm{Be}$ on two light targets ${}^9\mathrm{Be}$ and ${}^{28}\mathrm{Si}.$ Both the breakup from the projectile ground state and from core excited states is considered. We calculate and compare two interesting observables to existing experimental data. One is the total breakup cross section due to diffraction and stripping. Nice agreement with experimental data is obtained. The other is the ejectile energy spectrum corresponding to neutron stripping for a ${}^{28}\mathrm{Si}$ target, which was measured experimentally. We show that some part of the tail towards ejectile low energies is due to the contribution from core excited states which have initial angular momentum $l_i>0,$ binding energies of several MeV and as a consequence wide final energy spectra.

• Received 1 October 1999

DOI:https://doi.org/10.1103/PhysRevC.61.034605