K-shell x-ray production in 19K, 22Ti, 25Mn, and 35Br by 20-80-MeV 17Cl ions.

Abstract

Target K x-ray production cross sections have been determined for 20--80-MeV $_{17}\mathrm{Cl}^{\mathrm{q}+}$ (q=3--10) ions incident on vanishingly thin (\ensuremath{\sim}10 \ensuremath{\mu}g/${\mathrm{cm}}^{2}$) targets of $_{19}\mathrm{K}$, $_{22}\mathrm{Ti}$, $_{25}\mathrm{Mn}$, and $_{35}\mathrm{Br}$. In addition, intensity ratios ${I}_{K\ensuremath{\beta}}$/${I}_{K\ensuremath{\alpha}}$ and K\ensuremath{\alpha},K\ensuremath{\beta} x-ray energy shifts were measured. Using Hartree-Fock-Slater calculations and statistical scaling methods for multiple ionization, the number of 2p and 3p vacancies at x-ray emission is deduced from the K\ensuremath{\alpha} energy shifts and ${I}_{K\ensuremath{\beta}}$/${I}_{K\ensuremath{\alpha}}$, respectively. From the number of 2p and 3p vacancies at x-ray emission the fluorescence yield ${\ensuremath{\omega}}_{K}$ in the presence of this multiple ionization is then determined. The modified values of ${\ensuremath{\omega}}_{K}$, which are as much as 40% larger than the single-vacancy fluorescence yields, were used to compare the measured x-ray cross sections with theoretical predictions of ionization from the perturbed-stationary-state (PSS) theory with energy loss (E), Coulomb deflection (C), and relativistic (R) corrections, i.e., the ECPSSR theory of Brandt and Lapicki. Reasonable agreement with theory is obtained for $_{17}\mathrm{Cl}$${+}_{35}$Br (${Z}_{1}$/${Z}_{2}$\ensuremath{\sim}1/2) with the agreement becoming progressively worse, as expected, for ${Z}_{1}$/${Z}_{2}$\ensuremath{\rightarrow}1. The results provide evidence for the validity of the ECPSSR theory for collision systems with ${Z}_{1}$/${Z}_{2}$\ensuremath{\simeq}1/2 even when ${v}_{1}$/${v}_{2K}$\ensuremath{\simeq}0.3.