Regensburg 2007 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 30: Superconductivity - Cryodetectors
TT 30.7: Talk
Thursday, March 29, 2007, 18:30–18:45, H20
First experiments for precise Lamb shift measurements on hydrogen-like heavy ions with low temperature calorimeters — V. Andrianov1,2, K. Beckert1, P. Beller1, •A. Bleile1,2, P. Egelhof1,2, A. Gumberidse1, S. Illieva1,2, C. Kilbourne3, H.-J. Kluge1, S. Kraft-Bermuth1,2, D. McCammon4, J.P. Meier1,2, U. Popp1, R. Reuschl1, T. Stöhlker1, and S. Trotsenko1 — 1Gesellschaft für Schwerionenforschung, Darmstadt, Germany — 2Universität Mainz, Germany — 3Goddard Space Flight Center, Greenbelt, USA — 4Univ. of Wisconsin, Madison, USA
The precise determination of the Lamb shift in hydrogen-like heavy ions provides a sensitive test of quantum electrodynamics in very strong Coulomb fields, not accessible otherwise. To increase the accuracy of the Lamb shift measurement on stored heavy ions at the ESR storage ring at GSI, a calorimetric low temperature detector for hard X-rays was developed. The experimental requirements for the detector are the high absorption efficiency and a relative energy resolution of about 10−3 for 50-100 keV X-rays. A prototype array consisting of 8 pixels with silicon thermistors and Sn or Pb absorbers was recently applied in first experiments with stored 238U91+ and 208Pb81+ ions interacting with an internal gas-jet target. A total detection efficiency of 1x10−7 for the Lyman-α lines was reached and an energy resolution of 150 eV was obtained under the present experimental conditions. The results on the absolute energy determination of the Lyman-α lines will be discussed and the design of a new 32-pixel detector for future experiments will be presented.