L-subshell x-ray cross sections for proton collisions with Pt, Au, and Hg

Abstract

The $L$ x-ray production cross sections for the $L{\alpha }_{1,2}$, $L{\gamma }_{1,5}$, and $L{\gamma }_{2,3,6}$ transitions in Pt, Au, and Hg have been measured by ionization of the $L$-subshell electrons with 0.4-2.0-MeV proton bombardment. Individual subshell ionization cross sections, ${\sigma }_{L_i}(i=1, 2, or 3)$, have been extracted from the x-ray yields. Comparisons of the x-ray production and ionization cross-section data have been made with the predictions of the plane-wave Born approximation (PWBA), the PWBA with binding-energy and/or Coulomb-deflection effects, and the constrained binary-encounter approximation (CBEA). The binding-energy and Coulomb-deflection effects partially account for the gross quantitative discrepancies between the PWBA and the data for proton energies less than 1 MeV. Substantial discrepancy still exists, as evidenced by the disagreement between the data for $\frac{{\sigma }_{L_3}}{{\sigma }_{L_2}}$ and all the theoretical predictions.