Heavy-ion storage-ring quest for atomic lifetimes in Li+ and Be2+

Decays of metastable levels in the He-like ions Li+ and Be2+ were studied at a heavy-ion storage ring. The lifetimes involved span five orders of magnitude (from 0.5 ms to 50 s) and thus test the performance envelope of the experimental technique. For the 1s2s3S1 level in Be2+ ions, our lifetime result of (1.80 ± 0.05) s agrees with accurate nonrelativistic and relativistic calculations. While theory in these cases is expected to be well developed, experience reflects on the capabilities of the experimental arrangement. The time-resolved observations reveal information on cross sections for collisional de-excitation