Multiple ionization of M- and N-shells in heavy atoms by O, Si and S ions

Multiple ionization in M- and N-shells in solid Au, Bi, Th and U targets wa s studied for O, Si and S ions of energies 0.4-2.0 MeV/amu. L-gamma X-rays measured with semiconductor Si(Li) detector were analysed by using a newly developed method of the simultaneous determination of X-ray energy shifts a nd line broadening caused by the multiple ionization in outer shells. In th is approach both X-ray energy shifts and widths are expressed in terms of i onization probabilities and calculated energy shifts per vacancy, allowing thus the unique fitting of the L-gamma X-rays and determination of ionizati on probabilities. Derived ionization probabilities for M- and N-shells exhi bit universal scaling predicted by the geometrical model (GM) for the ioniz ation probabilities at the zero impact parameter. The influence of time evo lution of the vacancies formed in M- and N-shells by ion impact is discusse d. (C) 1999 Elsevier Science B.V. All rights reserved.