Measurement of atomic spectra and level lifetimes in multiply charged ions of astrophysical interest

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A principal goal of the project is the quality assurance of precise level lifetime measurements of low-lying levels in ions of astrophysical interest. To this end, systematic measurements have been undertaken at a heavy-ion storage ring, and large scale calculations of proven accuracy have been instigated for ions of several isoelectronic sequences. The measurements on one hand demonstrate the reliability (much better than 1% accuracy) of the storage ring technique for ions with an n=2 valence shell, but they also reveal the presence systematic error sources that can hamper the determination of lifetimes of n=3 valence shell ions by the population of specific long-lived 3d levels in the injector accelerator foil stripper. This particular systematic error must be different in other ion sources, and research is under way at the Livermore EBIT as well as at the Heidelberg heavy-ion storage ring TSR to clarify this point.