Proton- and 4He-ion-induced L-shell ionization of Pt, Pb and Bi

Abstract

L-shell x-ray production cross sections on selected heavy elements (Pt, Pb and Bi), some of which are of great importance from a biological point of view, have been measured by proton and 4He ion impact at energies ranging between 0.3 and 3.2 MeV and between 0.6 and 1.8 MeV, respectively. The data have been compared with the results of other laboratories, whenever existing, obtaining an overall good agreement. L-subshell ionization cross sections have been extracted and compared with the predictions of various theoretical approximations in the description of the ionization process. The disagreement observed at low values of the reduced velocity parameter LR between the data and the predictions of the ECPSSR model is significantly reduced by using a united-atom approximation in the treatment of the binding correction, as suggested by our group (ECPSSR-UA), and by replacing the screened hydrogen-like wavefunctions with the more realistic Dirac-Hartree-Slater ones. The application of a modified Coulomb deflection correction, recently suggested by our group, has further reduced the remaining discrepancies, predominantly in the case of impinging 4He ions.