FRAGMENTATION OF MOLECULAR HYDROGEN IONS IN COLLISIONS WITH ATOMIC AND MOLECULAR HYDROGEN TARGETS. P.C.E.McCartney*, C.McGrath*, J.W.McConkey**, M.B.Shah* and J.Geddes* * Department of Pure and Applied Physics, The Queen's University of Belfast, Belfast BT7 1NN, UK. ** School of Physical Sciences, University of Windsor, Ont N9B 3P4, Canada. The dissociation of molecular hydrogen ions with energies up to 100keV in H and H2 targets has been studied. A Si barrier detector is used to distinguish between production of one or more fast fragment ions or neutrals and coincidence techniques involving the slow ion or photon produced in the collision allows considerable detail regarding the relative dissociation channels to be obtained.