Monte Carlo simulation of characteristic x-ray emission from thick samples bombarded by kiloelectronvolt electrons

We describe systematic Monte Carlo (MC) calculations of characteristic K and L x-ray emission from thick samples bombarded by kiloelectronvolt electrons. The simulations were performed using the general-purpose MC code PENELOPE, which was modified by introducing a new database of electron-impact ionization cross sections calculated from the distorted-wave Born approximation (DWBA). The calculated yields, defined as the number of photons emerging from the target per unit solid angle and per incident electron, are compared with experimental measurements available from the literature, which pertain to single-element materials with atomic numbers ranging from Z = 6 up to Z = 82 and electron beam energies from a few kiloelectronvolts up to 40 keV. To reveal the dependence of the characteristic x-ray yields on the adopted ionization cross sections, simulations were also performed using cross sections based on the plane-wave Born approximation (PWBA). Our calculations confirm that, in the considered energy range, the DWBA is considerably more accurate than the PWBA.