Osnabrück 2002 – wissenschaftliches Programm
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A: Atomphysik
A 3: Experimentelle Verfahren
A 3.5: Vortrag
Dienstag, 5. März 2002, 15:15–15:30, HS 15/E10
Parity nonconservation from beams of highly charged ions — •Andrei Nefiodov, Guenter Plunien, and Gerhard Soff — Institut fuer Theoretische Physik, Technische Universitaet Dresden, Mommsenstr. 13, D-01062 Dresden
The most accurate experiment on parity-nonconservation (PNC) effects has been performed for neutral Cs atoms. A recent analysis indicates a possible deviation up to 2.2σ of the experimental value for the weak charge Qw of 133Cs from the value predicted by the standard model of electroweak interactions. The main uncertainty results from the theoretical evaluation of PNC matrix elements that require the inclusion of electron-electron correlations, the Breit interaction, and radiative corrections. To resolve this discrepancy, one can consider simpler electronic systems, in particular, heliumlike highly charged ions. Experiments with heavy ions could also provide a test of the standard model in strong fields and beyond the tree level. Instead of the standard measurement of circular dichroism which is rather difficult to perform for x-rays, one could propose a quenching-type experiment with interference of hyperfine- and weak-quenched transitions. The latter leads to an asymmetry of the photon emission relative to the ion beam polarization. With complete beam polarization, the magnitude of the asymmetry in photon counting rates reaches about 10−4 in europium isotopes. In heliumlike ions, there is also an unique opportunity to observe a net nuclear spin-dependent P-odd effect due to the near-degeneracy of the 1s2s 1S0 and 1s2p 3P1 levels for nuclear charge numbers Z close to 32.