Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 15: Superconductivity: Poster Session

TT 15.54: Poster

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

Metallic magnetic calorimeters with superconducting absorbers — •Christian Höhn, Richard Weldle, Jan-Patrick Porst, Andreas Burck, Chriatian Domesle, Sebastian Kempf, Stefan Lausberg, Lena Maerten, Andreas Pabinger, Christian Pies, Sönke Schäfer, Loredana Fleischmann, Andreas Fleischmann, and Christian Enss — KIP, Universität Heidelberg, INF 227, D-69120 Heidelberg, Germany

In metallic magnetic calorimeters (MMCs) the absorbed energy of incoming particles, e.g. X-rays, causes an increase of temperature in the detector which leads to a change of magnetisation in the Au:Er paramagnetic sensor. The resulting change in magnetic flux can be measured with a SQUID-magnetometer. As the flux change depends on the change of temperature which is inversely proportional to the heat capacity, it is attractive to use a superconducting absorber material. The first experiment presented here consists of a rhenium crystal as absorber with a gold foil glued on top that partly covers the surface of the absorber. The different pulse shapes that occur due to X-rays, either hitting directly the rhenium, therefore causing Cooper pairs to break, or the gold, producing a heat signal only phononically coupled to the rhenium, are presented. One idea to reduce the long rise time that occurs when superconductors are used as absorbers is to include magnetic impurities. These impurities reduce the energy gap of the superconductor which may lead to a faster quasiparticle recombination. The results obtained with MMCs having pure Al and Al:Mn absorbers are presented and the differences in pulse shape will be discussed.