Ultracold anions for high-precision antihydrogen experiments

Abstract

Experiments with antihydrogen ($\overline{\text{H}}$) for a study of matter--antimatter symmetry and antimatter gravity require ultracold $\overline{\text{H}}$ to reach ultimate precision. A promising path towards anti-atoms much colder than a few kelvin involves the pre-cooling of antiprotons by laser-cooled anions. Due to the weak binding of the valence electron in anions - dominated by polarization and correlation effects - only few candidate systems with suitable transitions exist. We report on a combination of experimental and theoretical studies to fully determine the relevant binding energies, transition rates and branching ratios of the most promising candidate La${}^{-}$. Using combined transverse and collinear laser spectroscopy, we determined the resonant frequency of the laser cooling transition to be $\nu =96.592713(91)$ THz and its transition rate to be $A=4.90(50)\times 10^4$ s${}^{-1}$. Using a novel high-precision theoretical treatment of La${}^{-}$ we calculated yet unmeasured energy levels, transition rates, branching ratios, and lifetimes to complement experimental information on the laser cooling cycle of La${}^{-}$. The new data establish the suitability of La${}^{-}$ for laser cooling and show that the cooling transition is significantly stronger than suggested by a previous theoretical study.

5 pages, 4 figures

References in corpus (4)

• Development of a configuration-interaction + all-order method for atomic calculations
• Laser Cooling of Molecular Anions
• Relativistic all-order calculations of Th, Th${}^{+}$ and Th${}^{2+}$ atomic properties
• A development of the CI + all-order method and application to the parity-nonconserving amplitude and other properties of Pb

Cited by in corpus (9)

• Observation of Electric-Dipole Transitions in the Laser-Cooling Candidate Th${}^{-}$
• Formation of ultracold ion pairs through long-range Rydberg molecules
• pCI: a parallel configuration interaction software package for high-precision atomic structure calculations
• Predicting quasibound states of negative ions
• Multiple photodetachment of atomic anions via single and double core-hole creation
• Ab initio MCDHF calculations of the In and Tl electron affinities and their isotope shifts
• Energy Levels and Transition Rates of Laser-Cooling Candidate Th^-
• Photodetachment Spectroscopy of Quasibound States of the Negative Ion of Lanthanum
• Investigating properties of Cl${}^{-}$ and Au${}^{-}$ ions using relativistic many-body methods