Hannover 2010 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 18: Precision Spectroscopy of Atoms and Ions II

A 18.9: Vortrag

Donnerstag, 11. März 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. Trassinelli¹ — ¹Gesellschaft 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 .