PROCESSES INVOLVING MULTIPLE IONIZATION IN COLLISIONS OF FAST H+ AND He2+ IONS WITH Pb ATOMS P.C.E. McCartney, M.B. Shah, J. Geddes and H.B. Gilbody Department of Pure and Applied Physics, The Queen's University of Belfast, Belfast, United Kingdom Individual cross sections for electron capture and pure ionization processes leading to up to 8 fold ionization of Pb atoms have been measured and shown to fit an independent electron model with only limited success.