Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 4: Matter at Low Temperature: Cryotechnique, Cryodetectors and Measuring Devices

TT 4.4: Vortrag

Montag, 23. März 2009, 12:15–12:30, HSZ 105

Progress in the micro-fabrication of high resolution magnetic calorimeters for x-ray spectroscopy — •Sönke Schäfer, Andreas Pabinger, Matias Rodrigues, Nadine Bleach, Thomas Wolf, Andreas Fleischmann, Loredana Fleischmann, and Christian Enss — KIP, Uni Heidelberg, INF 227, 69120 Heidelberg

Metallic magnetic calorimeters (MMC) are energy dispersive particle detectors with high energy resolution, that are operated at temperatures below 100 mK. MMCs consist of an absorber for the particles to be detected and a paramagnetic temperature sensor in tight thermal contact. The temperature rise upon the absorption of a particle, e.g. an x-ray photon, is detected via the change of the sensor’s magnetization, being monitored by a low-noise high-bandwidth dc-SQUID. The thermodynamic properties of MMCs can be calculated with confidence, allowing for a prediction of the responsivity and the noise of detectors with given geometry and, consequently, a numerical optimization of MMCs for a given application. We studied two different types of fully micro-fabricated MMCs, that were optimized for the detection of x-ray photons with energies up to 10 keV. One of which made use of a cylindrical sensor positioned in the circular loop of a dc-SQUID residing in an external magnetic field. The second was based on a planar temperature sensor, that was read-out by a meander-shaped superconducting pick-up coil, transformer-coupled to a dc-SQUID. Both detectors were characterized at a number of operating temperatures and magnetic fields. We present data of both detectors and compare their performance with each other as well as with theoretical predictions.