Momentum distributions and reaction mechanisms for breakup of two-neutron halos

A theoretical model able to describe fragmentation reactions of three-body halo nuclei on different targets, from light to heavy, is used to compute n eutron and core momentum distributions. Both Coulomb and nuclear interactio ns are simultaneously included. We specify the different reaction mechanism s related to various processes. The method is applied to fragmentation of H e-6 and Li-11 on C and Pb. We find good agreement with the available experi mental results. (C) 2001 Published by Elsevier Science B.V.