R. L. Watson

Target-atom K-shell ionization by binary-encounter electrons

Spectra of Kα x-rays emitted from Cu atoms bombarded with 10 MeV u-1 beams of Kr, Xe and Bi ions were measured with a curved crystal spectrometer. Large enhancements of the Kα diagram lines were observed and attributed to secondary ionization by photons and electrons. To explain these results quantitatively, contributions from binary-encounter electrons have been calculated by considering their production and transport as well as the effective cross section for target K-shell ionization by electron impact. The results are in good agreement with the measurements.

K X-ray spectra of highly charged recoil ions produced by heavy-ion impact on oxygen

High-resolution oxygen K X-ray spectra of recoil ions produced by impact of 0.68 MeV amu-1 Ar and 1.4 MeV amu-1 C, Mg and Ar ions on oxygen-bearing molecular targets have been measured using a curved-crystal spectrometer. The spectra are dominated by H-like, He-like and Li-like transitions of the series np-1s, 1snp-1s2 and 1s2lnp-1s22l. A detailed analysis of the multiplet line structure of one-, two- and three-electron satellite and hypersatellite states for oxygen excited by 0.68 MeV amu-1 Ar11+ has been carried out. The overall structure of the spectra was found to be remarkably insensitive to the chemical composition of the target, although several particular features did display chemical effects. Measurements of the intensity ratio (1P/3P) for transitions from the 1s2p He-like oxygen states revealed a highly non-linear dependence on pressure.