Proton- and 4He-ion-induced L-subshell ionization of rare-earth elements

L X-ray production cross sections for proton and 4He-ion bombardment of 62≤Z≤70 elements have been measured in the energy range 0.25-180 MeV for protons and 0.40-1.80 MeV for helium ions. Subshell ionization cross sections have been extracted and compared with the predictions of the ECPSSR theory and with those of a modified model (UA-ECPSSR) suggested by us, based on a recalculation of the binding correction. Significant improvements have been obtained in the latter case. The residual discrepancies observed at the lowest incident energies have been attributed to the inadequate way of calculating the Coulomb retardation and relativistic corrections. An attempt to remove these discrepancies by introducing the Coulomb correction described in the work of Lapicki and Losonsky, instead of a pure exponential reduction factor of the cross sections, has given satisfactory results. (orig.)