Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 24: Superconductivity: Cryodetectors
TT 24.8: Vortrag
Mittwoch, 29. März 2006, 18:30–18:45, HSZ 02
First test experiment for precise Lamb shift measurements on hydrogen-like heavy ions with low temperature calorimeters — •V. Andrianov1, K. Beckert1, P. Beller1, A. Bleile1, P. Egelhof1, A. Gumberidze1, C. Kilbourne2, H. J. Kluge1, S. Kraft-Bermuth1, D. McCammon3, J. P. Meier1, U. Popp1, R. Reuschl1, T. Stöhlker1, and S. Trotsenko1 — 1Gesellschaft für Schwerionenforschung, Darmstadt, Germany — 2Goddard Space Flight Center, Greenbelt, USA — 3Univ. 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 238U91+ ions at the ESR storage ring at GSI, a high-resolution calorimetric low temperature detector for hard X-rays was developed. The experimental requirements for the detector are a high absorption efficiency and a relative energy resolution of about 10−3 for 50–100 keV X-rays. The detector consists of arrays of silicon thermistors and X-ray absorbers made of high-Z material. A test array consisting of 4 pixels was recently applied in a first test experiment for Lamb shift measurement at the ESR. A 89 MeV/u 238U92+ beam stored in the ESR interacted with a 1011 cm−3 internal argon gas-jet target. The Lyman-α lines emitted from the charge-exchanged 238U91+ ions were clearly identified. An energy resolution of ΔE = 149 eV was obtained at Eγ = 70 keV and a total detection efficiency of 1 x 10−7 was reached. The results of this test experiment as well as future perspectives will be discussed.