Nuclear induced breakup of halo nuclei

We investigate the validity of approximations that are sometimes made in ca lculating the nuclear induced breakup of halo nuclei. We find that a trunca ted coupled-channels calculations, in which the nuclear couplings between c ontinuum states are ignored, gives almost the same result as a first-order calculation. However, the couplings are much too strong to justify these ap proximations. This is demonstrated in the frozen limit of a semiclassical d escription, where one can compare to exact results. We find in this limit t hat the one-neutron removal cross section of Be-11 obtained in the approxim ate treatment is much larger than the exact result. This trend is also indi cated at low energy by comparing a perturbative calculation of the breakup of B-8 to the result of a more realistic treatment, which evolves the wave function of the valence proton essentially to all orders in the target fiel ds. [S0556-2813(99)01406-5].