Atomic lifetime measurements on forbidden transitions of Al-, Si-, P- and S-like ions at a heavy-ion storage ring

Abstract

Lifetimes of 3s23pk ground configuration levels of Al-, Si-, P- and S-like ions of Fe, Co and Ni have been measured at a heavy-ion storage ring. Some of the observed decay curves show strong evidence of cascade repopulation from specific 3d levels that feature lifetimes in the same multi-millisecond range as the levels of the ground configuration. We identify the foil-stripping process in the ion production as the cause of the cascade level population and assess the importance of specific cascades for the measurement technique.