Abstract
The strong ¯p-nucleus spin-orbit interaction was investigated in a measurement of the strong-interaction effects of the 9→8 transition in ¯p 174Yb at the Low-Energy Antiproton Ring (LEAR) at CERN. This measurement was part of an experimental programme where, for the first time, the fine-structure components of the last observable X-ray transition in a ¯p atom, which carries information on the strong ¯p-nucleus interaction, were resolved and studied individually. The observed splitting ΔE exp=2408±26 eV consists of the electromagnetic fine-structure splitting ΔE FS=2350 eV and an additional splitting Δɛ=58±26 eV. In addition, one finds a significant difference in the level widths of Δ=195±59 eV with the larger value⇊=1216±41 eV for the lower fine-structure level. This experiment follows an earlier measurement on ¯p 138Ba, where the transition 8→7 is influenced by the strong interaction. In this case, however, the fine-structure components could not be resolved. The results for174Yb may be attributed to a spin-orbit (LS) term in the complex strong-interaction potential.
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This publication forms part of the thesis of A. Kreissl
We would like to thank D. Simon, D. Dumollard and the LEAR staff for their collaboration during the data taking of this experiment. The numerical calculations of the antiprotonic energy eigenvalues were done by E. Borie and B. Jödicke. For technical assistance we are grateful to H. Hagn, J. Hauth and M. Meyer. The work was supported by the Bundesministerium für Forschung und Technologie of the Federal Republic of Germany, the Swiss National Science Foundation, and the US National Science Foundation.
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Kreissl, A., Hancock, A.D., Koch, H. et al. First direct observation of strong interaction spin-orbit effects in antiprotonic atoms. Z. Physik A - Atomic Nuclei 329, 235–241 (1988). https://doi.org/10.1007/BF01283780
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DOI: https://doi.org/10.1007/BF01283780