BEAM-FOIL STUDY OF THE LIFETIMES OF N=3 LEVELS IN NA-LIKE CA-X, MG-LIKE CA-IX AND SI-LIKE CA-VII

Levels of Ca ions with one, two or four electrons in the n = 3 shell h ave been studied for their decay properties and lifetimes. For the 3p (2p0) (1/2,3/2) levels of Ca X and the 3s3p (1p0) (1) level of Ca IX, arbitrarily normalized decay curve (ANDC) and cascade model analyses y ield results with precisions of 10% and less and with low systematic u ncertainties. The measured lifetime of the Ca IX 3s3d(1)D(2) level con firms the need to include relativistic effects in the calculation. The lifetime results are compared to other, experimental and theoretical, data available for the isoelectronic sequences.