Momentum distribution of fragments in reactions induced by neutron rich nuclei

We calculate the longitudinal and transverse momentum distributions of the fragments 9Li, 10Be and 12Be emitted in the reactions induced by the neutron rich nuclei 11Li, 11Be and 14Be respectively on several targets at different beam energies within a direct fragmentation model. For all the cases, the shapes of the longitudinal momentum distributions are found to depend very weakly on the interactions governing the fragmentation. However, both widths and the absolute magnitudes of the transverse momentum distributions are sensitive to the fragment-target interactions. Comparisons with the recent experimental data are made to support our conclusions.