Mainz 2017 – scientific programme

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A: Fachverband Atomphysik

A 4: Precision Spectroscopy I

A 4.7: Talk

Monday, March 6, 2017, 16:15–16:30, N 3

Determination of ground-state hyperfine splitting energies in Bi^{80+, 82+} ions to test QED — •Johannes Ullmann^1,2, Zoran Andelkovic³, Carsten Brandau^3,11, Andreas Dax⁸, Wolfgang Geithner³, Christopher Geppert², Christian Gorges², Michael Hammen^5,7, Volker Hannen⁴, Kristian König³, Simon Kaufmann², Yuri Litvinov³, Matthias Lochmann², Bernhard Maass^2,3, Johann Meisner⁶, Tobias Murböck¹⁰, Rodolfo Sánchez³, Stefan Schmidt^2,7, Matthias Schmidt⁶, Markus Steck³, Thomas Stöhlker^1,3, Richard C. Thompson⁹, Christian Trageser¹¹, Jonas Vollbrecht⁴, Christian Weinheimer⁴, and Wilfried Nörtershäuser² — ¹Helmholtz Inst. Jena — ²Inst. f. Kernphysik, TU Darmstadt — ³GSI Darmstadt — ⁴Inst. f. Kernphysik, Uni Münster — ⁵Helmholtz Inst. Mainz — ⁶PTB Braunschweig — ⁷Inst. f. Kernchemie, Uni Mainz — ⁸PSI, Villigen, Switzerland — ⁹Imperial College London, UK — ¹⁰Inst. f. Angew. Physik, TU Darmstadt — ¹¹I. Phys. Institut, Uni Gießen

The measurement of the ground state hyperfine splittings in Bi⁸²⁺ and Bi⁸⁰⁺ ions tests the theory of bound-state quantum electrodynamics (QED) in the strong field of the nucleus. Precise theoretical predictions use a specific difference of both splitting energies to cancel the large uncertainty of nuclear contributions. In the recent laser spectroscopy beamtime at the storage ring ESR at GSI Darmstadt, we reduced the largest experimental uncertainty by an order of magnitude. Systematic effects will be discussed and we will present the first high precision value of the specific difference, which deviates significantly from theory.