Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 15: Superconductivity: Poster Session

TT 15.53: Poster

Dienstag, 26. Februar 2008, 14:00–18:00, Poster B

Development of a Fully Microfabricated Two Pixel Magnetic Calorimeter — •S. Schäfer, A. Burck, C. Domesle, C. Höhn, S. Kempf, S. Lausberg, A. Pabinger, C. Pies, J.-P. Porst, R. Weldle, A. Fleischmann, L. Fleischmann, and C. Enss — Kirchhoff-Institut für Physik, Im Neuenheimer Feld 227, 69120 Heidelberg

The feasibility to microfabricate single metallic magnetic calorimeter detectors and detector arrays has been studied. These detectors consist of an absorber for x-rays and a paramagnetic temperature sensor placed in a weak magnetic field. At working temperatures below 100 mK any energy deposition in the detector produces a temperature rise which changes the magnetization of the sensor material. By a read out scheme with sensitive low noise SQUID magnetometers, the absorption of single x-ray quanta can be detected and their energy can be measured precisely. The steps of a microfabrication process were developed and optimized which allows for a fabrication of calorimeter arrays with mushroom shaped detectors increasing the sensible area by overhanging absorbers. On a single chip, two detectors were fabricated and read out by two separate circuits. Due to this special setup, it was possible to analyze the crosstalk between both pixels. In addition to measurements in the flux-locked-loop mode, magnetization measurements and spectra were obtained in open-loop mode. In this mode of operation electro-thermal-feedback effects were observed which result in changing the decay times of the pulses. In particular, in this mode faster pulses can be achieved which allows higher count rates.