Dynamic screening energy shifts and collision broadening of 2p->1s transitions in 2 MeV/amu H- and He-like Ne, Mg and S ions

The spectra of K X-rays emitted by 2 MeV/amu Ne, Mg, and S ions in a thick carbon target were measured with a curved-crystal spectrometer. Energy shifts of the hydrogen-like ion 22P -> 12S transition and the helium-like ion 21P -> 11S transition were determined by means of energy calibrations obtained from thin target spectra, for which X-ray emission occurred almost entirely in vacuum. The spectra were fitted with a least-squares program employing Voigt functions to extract accurate peak centroids and, in the thick target cases, Lorentzian widths. The energy shifts were compared to those determined previously for S ions and found to be much smaller than expected on the basis of a dynamic screening model. The Lorentzian widths were found to increase slowly with decreasing projectile Z, and those for the 2P transition were approx.=50% smaller than those for the 1P transition. (orig.)