Dresden 2011 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 21: Atomic systems in external fields II
A 21.6: Vortrag
Donnerstag, 17. März 2011, 15:15–15:30, BAR 205
Nuclear spin-dependent parity-violation asymmetry in hyperfine transitions in He-like ions — •Fabrizio Ferro1,2, Andrey Surzhykov1,2, and Thomas Stöhlker1,2,3 — 1Physikalisches Institut, Universität Heidelberg, Germany — 2GSI-Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany — 3Helmholtz-Institut Jena, Germany
Parity-violation (PV) in atomic systems offers a unique possibility to test the electroweak theory at very low energies. In atoms with non-zero nuclear spin, I≠ 0, the nuclear parity-violating anapole moment interacts magnetically with electrons. This leads to the appearance of parity-forbidden electromagnetic transitions between atomic levels. Recent efforts have been targeted at measuring the anapole moment in neutral atoms. Instead, we propose an alternative way, by employing He-like ions as available at storage ring facilities (e.g. ESR-GSI), and taking advantage of the precision spectroscopy techniques available for highly-charged ions. We show that by stimulating the transition between the hyperfine levels (1s2s) 1S0 (F=I) and (1s2s) 3S1 (F′=I−1,I,I+1) with circularly-polarized laser light, an interference term between the allowed M1 multipole and the E1 parity-violating multipole may be observed in the cross section. By performing this experiment with ions in the range 28≤ Z≤ 35 alternatively with left- and right-polarized light, an asymmetry of order 10−7 in the cross section is expected. In the last part of the talk, we discuss the key experimental requirements for such a measurement, and show how the asymmetry directly relates to the nuclear weak charge.