Berlin 2001 – wissenschaftliches Programm

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A: Atomphysik

A 17: Posters Friday (Spectroscopy)

A 17.30: Poster

Freitag, 6. April 2001, 12:30–15:00, AT3

QED Corrections in Helium-like Highly-Charged Ions — •Björn Åsén, Sten Salomonson, Ingvar Lindgren, and Eleanor Campbell — Chalmers University of Technology and Göteborg University

The interest in Quantum ElectroDynamic (QED) applications to atomic systems, bound state QED, has been enhanced significantly in recent years, mainly through the experimental success in producing and studying highly charged ions. These heavy few-electron systems are extremely relativistic and provide an excellent test of both relativity and QED in a region not previously carefully investigated. For highly-charged ions it is appropriate to make an expansion of the total electromagnetic interaction in terms of the number of exchanged photons, but an expansion in the binding potential is not appropriate. Extending our previous work on the corrections to the one-photon exchange effect in the ground-state of helium-like ions [1,2] we have now performed two-photon exchange calculations on excited states in helium-like systems. A theory has also been developed for evaluating the QED contributions to an effective Hamiltonian within a space of quasi-degenerate levels. This is applied to the quasi-degenerate 1s2p1/2 and 1s2p3/2 levels in He-like systems, and is important in the low Z-region but may have a significant effect also in the medium Z-region.

[1]Full QED calculations of two-photon exchange for helium-like systems: Analysis in the Coulomb and Feynman gauges I Lindgren, H Persson, S Salomonson and L Labzowsky Physical Review A51, 1167 (1995)

[2]Two-Electron Lamb-Shift Calculations on Heliumlike Ions Hans Persson, Sten Salomonson, Per Sunnergren and Ingvar Lindgren Physical Review Letters 76, 204 (1996)