Two-neutron removal reactions of 6He treated as a three-body halo

We formulate a method to compute breakup processes of three-body halo systems reacting with a target. The reaction between one of the particles and the target as well as the corresponding pairwise final state interactions are carefully treated. Both absorption and diffraction processes are included. Detailed differential and total cross sections are calculated for two-neutron (2n) removal from 6He by fragmentation on 12C. Effects due to the core shadowing are taken into account. Good agreement with available experimental data is obtained.