Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 8: Superconductivity - Poster Session

TT 8.37: Poster

Montag, 26. März 2007, 14:00–17:45, Poster A

Properties of superconducting rhenium absorber for low temperature detectors — •J.-P. Porst¹, L. Gastaldo¹, S. Schäfer¹, M. Linck¹, A. Burck¹, S. Kempf¹, H. Rotzinger¹, A. Fleischmann¹, C. Enss¹, V. Zakosarenko², R. Stolz², and H.-G. Meyer² — ¹Kirchhoff-Institut für Physik, Universität Heidelberg, INF 227, D-69120 Heidelberg, Germany — ²Institute for Physical High Technology, Albert-Einstein-Str.9, D-07702 Jena, Germany

A still puzzling problem in the development of low temperature micro-calorimeters for the measurement of ¹⁸⁷Re β-spectrum, is the understanding of the thermalization of energetic electrons in the superconducting rhenium absorber. We developed a metallic magnetic calorimeter (MMC) with a single crystal Re absorber and paramagnetic Au:Er temperature sensor. The energy released into the detector leads to a change of magnetization of the paramagnetic sensor located in a weak magnetic field. A meander shaped SQUID magnetometer is used to read out this change. This setup allows the study of several properties of the rhenium single crystal. The transition to the superconducting state is studied by measuring the magnetic flux expelled by the Re sample. The resistivity of Re above T_C can be estimated from the measurement of the spectral power density of the Johnson noise. Furthermore the quasiparticle lifetime can be investigated through the analysis of heat pulses caused by the absorption of X-rays. We present the data obtained in these experiments and discuss the physical quantities which can be derived from these.