L-subshell ionization cross sections for proton bombardment of Ag, In, Sn, and I

Abstract

$L$---x-ray production cross sections were measured for thin targets of Ag, In, Sn, and I in the proton energy range 0.300-5.000 MeV. Subshell ionization cross sections were extracted and compared with existing data and with the predictions of plane-wave Born approximation (PWBA), perturbed---stationary-state theory including energy loss, Coulomb deflection and relativistic corrections (ECPSSR), binary-encounter approximation with corrections accounting for binding effect and Coulomb retardation (BEABC), and semiclassical approximation taking into account binding, energy loss, Coulomb deflection, and relativistic effects (SCABCR). Large disagreement was found with PWBA, but the other theories reproduced the experimental data rather well. Owing to the nodal structure of the $2s$ wave function, deeper insight was achieved by considering the ratios of the sub-shell ionization cross sections. These results were found to be in good agreement with analogous measurements on high-$Z$ elements and favor the ECPSSR over the other theories. A realistic value for the ${\ensuremath{\omega}}_{1}$ fluorescence yield was suggested for indium near the discontinuity at $Z\ensuremath{\sim}50$.