Reaction mechanisms for two-neutron halo breakup

We describe a reaction mechanism which is consistent with all available exp erimental information of high energy three-body breakup processes. The domi nating channels are removal of one of the three halo particles leaving the other two either undisturbed or absorbed. We compare with the commonly used deceptive assumption of a decay through two-body resonance states. Our pre dictions can be tested by measuring neutron-neutron invariant mass spectra.