X-ray production cross sections, intensity ratios, and centroid energy shifts ofAg KandLandAu Lx rays produced byO16beams of 12-50 MeV

Abstract

The 12-50-MeV $^{16}\mathrm{O}$ beam-induced $K$ and $L$ x rays of Ag and the $L$ x rays of Au from thin targets were studied with a Si(Li) detector. Absolute $K$ and $L$ x-ray production cross sections were derived from measured x-ray yields and compared to available theoretical calculations for inner-shell Coulomb ionization cross sections. Inclusion of Coulomb repulsion, binding, and ${(\frac{{Z}_{1}}{{Z}_{2}})}^{3}$ effects in the plane-wave Born-approximation calculations gives good agreement with experimental values of ${\ensuremath{\sigma}}_{\mathrm{KX}}$ for Ag. The agreement between theory and experiment for $L$-shell ionization is not as good, possibly owing to the effects of multiple ionization on the fluorescence yield, although the energy dependence of ${\ensuremath{\sigma}}_{\mathrm{LX}}$ for Au is well reproduced. The energies of the $\mathrm{Ag} K \ensuremath{\alpha}$ and $K \ensuremath{\beta}$ and $\mathrm{Au} L \ensuremath{\alpha}$, $L \ensuremath{\beta}$, and $L \ensuremath{\gamma}$ lines were observed to change with beam energy as did the intensity ratios of these lines. HFS calculations for the $\mathrm{Ag} K \ensuremath{\alpha}$ and $K \ensuremath{\beta}$ lines indicate that the observed shifts are probably associated with multiple $M$-, not $L$-, shell ionization.