Level lifetimes in 3p and 3d configurations of Fe XII.

Transitions between the five fine-structure levels in the 3 s²3 p³ ground configuration of Fe XII (P-like) are of interest in astrophysics and terrestrial plasma diagnostics. The decay rates give rise to level lifetimes in the millisecond range, which have been measured recently at a heavy-ion storage ring. While most of the 3 s²3 p²3 d levels are short-lived, two of these levels have no E1 decay channels and may also have millisecond lifetimes. We present HFR and MCDF calculations of the E1, M1, E2 and M2 transition rates between the 3 s²3 p³, 3s3p⁴ and 3 s²3 p²3 d levels and compare the lifetime results to most recent experimental data as well as to other predictions. [ABSTRACT FROM AUTHOR]