Berlin 2008 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 15: Superconductivity: Poster Session

TT 15.55: Poster

Tuesday, February 26, 2008, 14:00–18:00, Poster B

Electrodeposition of gold absorbers for metallic magnetic calorimeters — •Christian Pies, Stefan Lausberg, Andreas Burck, Christian Domesle, Christian Höhn, Sebastian Kempf, Lena Maerten, Andreas Pabinger, Jan-Patrick Porst, Sönke Schäfer, Richard Weldle, Thomas Wolf, Andreas Fleischmann, Loredana Fleischmann, and Christian Enss — Kirchhoff-Institut für Physik, Im Neuenheimer Feld 227, D-69120 Heidelberg, Germany

Metallic magnetic calorimeters are increasingly used for particle detection. A metallic paramagnetic sensor is situated in a weak magnetic field. Incident particles, like x-rays, dissipate their energy inside a gold absorber which is thermally well connected to the sensor. The temperature rise in the absorber causes a rearrangement of magnetic moments in the sensor. This change in magnetization is read out by a two-stage SQUID setup.

In order to stop x-rays in the energy range of more than 100 keV, gold absorbers of several hundred microns in thickness are needed. Techniques like sputtering or vapor deposition can effectively produce films of no more than a few microns. Therefore an electrodeposition process was developed to fabricate thick gold layers with high purity and better residual resistivity ratio than sputtered or evaporated films. We use sulfite based gold electrolytes which can produce films of more than 200 microns. In order to control the geometry of the electrodeposited absorbers, we use the SU-8 negative photoresist, which can be structured up to 1 mm in thickness with a high aspect ratio.