<正>In the study of dissociation or ionization process of atoms and molecules induced by electron, photon, or ion beams, if the momentum of the n-1 particles can be determined among the total n particles after interaction, the differential cross section can be deduced. Position sensitive detector with microchannel plate and standard helical wire delay line anode (DHL) is used to determine the momenta of the n-1 particles in reaction microscope. :