X-ray emission from foil-exited sulphur beams

Emission of Kα x rays from foil-excited sulphur beams at 40, 50, and 55 MeV has been observed. Lifetimes of the (1s2p)³P₂ state in helium-like and the (1s2s2p)⁴P5/2 state in lithium-like sulphur, which decay partially by magnetic-quadrupole transitions, have been determined. The energies of several transitions to the ground state in two- and three-electron sulphur ions have been determined by using a Doppler-tuned spectrometer and observing the beam both downstream and close to the exciting foil. It is pointed out that the identification of lines in the prompt spectrum of such highly ionized systems in terms of configuration-averaged satellites is inappropriate.