Balmer α transitions in antiprotonic hydrogen and deuterium

Abstract

The strong-interaction shifts ϵ and broadenings Γ of the 2p levels in antiprotonic hydrogen and deuterium have been measured for the first time with a crystal spectrometer. In hydrogen, the 2 3 P 0 hyperfine state could be resolved from the three close-lying states 2 3 P 2 , 2 1 P 1 , and 2 3 P 1 . The hadronic shift was determined to be ϵ 2 3 P 0 =+139±28 meV (attractive). The value found for Γ 2 3 P 0 =120±25 meV is much larger than the spin-averaged 2p-level broadening Γ ̄ bal 2p as determined from earlier experiments measuring the intensity balance. The average shift of the three unresolved states is consistent with zero and a mean broadening of Γ ̄ 2( 3P 2, 1P 1, 3P 1) =38±9 meV was measured. In deuterium, the spin-averaged hadronic shift and broadening were found to be ϵ ̄ 2p =−243±26 meV (repulsive) and Γ ̄ 2p =489±30 meV.