This brief report is a follow-up to the recent proposal to use La${}^{-}$ as another candidate, in addition to Os${}^{-}$, in laser cooling of anions, which can then be used to cool antiprotons sympathetically. Using the relativistic configuration interaction formalism, we calculate the photodetachment cross sections of the upper laser cooling state La${}^{-}$ $5d$$6s^2$$6p\hspace{0.5em}{}^3{D}_1$ and Os${}^{-}$ $5d^6$$6s^2$$6p\hspace{0.5em}{}^6{D}_{9/2}$. Our results show that La${}^{-}$ has a very similar two-photon detachment loss as Os${}^{-}$, retaining it as another promising candidate for cooling antiprotons sympathetically.

• Received 17 May 2010

DOI:https://doi.org/10.1103/PhysRevA.82.014501