Balmer alpha transitions in antiprotonic hydrogen and deuterium

The strong-interaction shifts epsilon and broadenings Gamma of the 2p level s in antiprotonic hydrogen and deuterium have been measured for the first t ime with a crystal spectrometer. In hydrogen, the 2 P-3(0) hyperfine state could be resolved from the three close-lying states 2 P-3(2), 2 P-1(1), and 2 P-3(1). The hadronic shift was determined to be epsilon(2 3P0) = + 139 /- 28 meV (attractive). The value found for Gamma(2 3P0) = 120 +/- 25 meV i s much larger than the spin-averaged 2p-level broadening <(Gamma)over bar>( bal)(2p) as determined from earlier experiments measuring the intensity bal ance. The average shift of the three unresolved states is consistent with z ero and a mean broadening of <(Gamma)over bar>(2(3P2, 1P1, 3P1)) = 38 +/- 9 meV was measured. In deuterium, the spin-averaged hadronic shift and broad ening were found to be <(epsilon)over bar>(2p) = -243 +/- 26 meV (repulsive ) and <(Gamma)over bar>(2p) = 489 +/- 30 meV. (C) 1999 Elsevier Science B.V . All rights reserved.