Balmer α transitions in antiprotonic hydrogen and deuterium Original Research Article

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 2View the MathML source hyperfine state could be resolved from the three close-lying states 2View the MathML source, 2View the MathML source, and 2View the MathML source. The hadronic shift was determined to be View the MathML source meV (attractive). The value found for View the MathML source meV is much larger than the spin-averaged 2p-level broadening View the MathML source 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 View the MathML source meV was measured. In deuterium, the spin-averaged hadronic shift and broadening were found to be View the MathML source meV (repulsive) and View the MathML source meV.