Storage-ring experiments with 10–100-keV Ca- beams: Role of blackbody radiation

The lifetime of 10–100-keV Ca- beams in a heavy-ion storage ring was measured to be ∼490 μs. A combination of experimental and theoretical evidence strongly suggests that the observed decay is associated with blackbody-radiation-induced photodetachment of Ca-(4s24p 2P) ground-state ions at room temperature. Blackbody-radiation effects may also explain the previously reported existence of a long-lived (290±100 μs) metastable Ca-(4s4p2 4P) ion [D. Hanstorp et al., Phys. Rev. Lett. 63, 368 (1989)].