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Hannover 2010 – scientific programme

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A: Fachverband Atomphysik

A 18: Precision Spectroscopy of Atoms and Ions II

A 18.9: Talk

Thursday, March 11, 2010, 12:30–12:45, F 107

Precise measurement of the Lamb shift in hydrogen-like lead ions with low-temperature microcalorimeters — •S. Kraft-Bermuth1, V. Andrianov1, K. Beckert1, A. Bleile1, Ch. Chatterjee1, A. Echler1, P. Egelhof1, A. Gumberidze1, S. Ilieva1, O. Kiselev1, C. Kilbourne2, H.-J. Kluge1, D. McCammon3, J. P. Meier1, R. Reuschl1, T. Stöhlker1, and M. Trassinelli11Gesellschaft für Schwerionenforschung, Darmstadt, Germany — 2NASA/Goddard Space Flight Center, Greenbelt, USA — 3Department of Physics, University of Wisconsin, Madison, USA

The precise determination of the energy of the Lyman-α energies in hydrogen-like heavy ions provides a sensitive test of quantum electrodynamics in very strong Coulomb fields. We present the final results of the first measurement of the Lyman-α lines of lead ions Pb81+ with a low-temperature microcalorimeter at the Experimental Storage Ring (ESR) at GSI. The prototype detector array consisted of 8 silicon thermistors with Sn and Pb absorbers, for which an average energy resolution of 130 eV was obtained for 59 keV X-rays. The measured energy of the Lyman-α1 line in the emitter frame was E(Ly-α1,Pb81+)=77.937(26) keV, which agrees well with the theoretical prediction. The systematic error is mainly due to uncertainties in the positions of the pixels as well as the width of the gas-jet target. To improve the statistics, a new array with 32 pixels has been equipped; first tests yielded an average energy resolution of 43 eV for 59 keV X-rays. The talk will report on the current status and discuss perspectives for the Lamb shift experiment with the improved performance .

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