M-SHELL X-RAY-PRODUCTION CROSS-SECTION MEASUREMENTS IN PB AND BI DUE TO THE IMPACT OF PROTONS AND NICKEL IONS

M-shell x-ray production cross sections in Pb have been measured using 58-82 MeV Niq+ (q = 5,6) ions and those in Bi by 1-5 MeV protons and 58-82 MeV Niq+ ions (q = 5, 6). The experimental results have been com pared with the predictions of the plane-wave Born approximation (PWBA) and with the calculations of the perturbed stationary state theory (E CPSSR) accounting for the energy loss (E), Coulomb deflection (C) and relativistic (R) effects. The present results of proton impact on bism uth have also been compared with the experimental data available from other investigations. To the best of our knowledge, the M-shell x-ray production cross sections in Pb and Pi by Ni-ion impact are reported h ere for the first time. Good agreement of the present results with the predictions of the ECPSSR theory has been observed for the total M x- ray cross sections in Bi due to proton impact while discrepancies to a factor of 1.5-2.5 in the case of total M x-ray cross sections have be en observed between the present experimental and theoretical (PWBA and ECPSSR, respectively) results for Pb and Bi in the case of Ni-ion imp act. These discrepancies between the experimental and theoretical resu lts could be attributed to the effect of multiple ionization on the x- ray emission probabilities. If the modified value of the average fluor escence yield accounting for the outer-shell multiple ionization is us ed, the theoretical results of total M-shell x-ray cross sections base d on the PWBA theory show fair agreement with the experimental results (within experimental uncertainties) while the ECPSSR theory is found to underestimate the experimental results by about 40% for both Pb and Bi in the case of Ni-ion impact. Furthermore, the M alpha beta, M gam ma and (M3O1,4,5 + M2N4) x-ray cross sections have been evaluated expe rimentally for both Pb and Bi. The comparison of these results with th e corresponding theoretical estimates have been done only for Pb as th e emission rates for various M x-ray transitions of Bi are not availab le in the literature. The comparison of the M alpha beta cross section s show fair agreement with the PWBA-based theoretical values, while th ere are discrepancies of a factor of 10 and 20 in the cases of M gamma and (M3O1,4,5 + M2N4) x-ray transitions.