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TT: Fachverband Tiefe Temperaturen

TT 12: Symposium: Cryodetectors and SQUID

TT 12.3: Vortrag

Dienstag, 26. Februar 2008, 10:30–11:00, H 0104

Metallic magnetic calorimeters for high resolution x-ray spectroscopy and particle detection — •Loredana Fleischmann — Kirchhoff-Institut für Physik, Universität Heidelberg, INF 227, 69120 Heidelberg

An increasing number of experiments and applications employ low temperature particle detectors which are based on a calorimetric detection scheme and operated at temperatures below 100 mK. In many cases this is due to the high energy resolution achievable with these detectors. Equally important benefits are often the increased flexibility in the choice of absorber materials and the fact that the detection efficiency is independent of the ionizing character of the particles to be detected.

Metallic magnetic calorimeters (MMC) make use of a metallic paramagnetic temperature sensor, which is in tight thermal contact with an absorber for the particles of interest. The paramagnetic sensor is placed in a small magnetic field. Its magnetization is used to monitor the temperature, which in turn is related to the internal energy of the calorimeter. High energy resolution can be obtained by using a low-noise, high-bandwidth DC SQUID to measure the small change in magnetization upon the absorption of energy.

With recent x-ray detector prototypes an energy resolution of a few eV for x-ray energies up to 6 keV has been achieved. We discuss the thermodynamic properties, the energy resolution, the microfabrication and general design considerations of MMCs as well as their application in high resolution x-ray spectroscopy, beta spectroscopy and absolute activity measurements.