The lifetime of 10–100-keV ${\mathrm{Ca}}^{\mathrm{-}}$ 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 ${\mathrm{Ca}}^{\mathrm{-}}$(4${\mathit{s}}^2$4p ${}_{}{}^2{}_{}{}^{}$P) ground-state ions at room temperature. Blackbody-radiation effects may also explain the previously reported existence of a long-lived (290±100 μs) metastable ${\mathrm{Ca}}^{\mathrm{-}}$(4s4${\mathit{p}}^2$ ${}_{}{}^4{}_{}{}^{}$P) ion [D. Hanstorp et al., Phys. Rev. Lett. 63, 368 (1989)].

• Received 27 April 1992

DOI:https://doi.org/10.1103/PhysRevA.46.R1