Regensburg 2007 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 30: Superconductivity - Cryodetectors

TT 30.1: Talk

Thursday, March 29, 2007, 17:00–17:15, H20

Development of magnetic calorimeters with superconducting Re absorber for ν mass experiments — •L. Gastaldo, J.-P. Porst, S. Schaefer, M. Linck, A. Burck, S. Kempf, H. Rotzinger, A. Fleischmann, and C. Enss — Kirchhoff-Institut fuer Physik, Universitaet Heidelberg, INF 227, D-69120 Heidelberg, Germany

Direct measurement of ν_e mass is in principle possible by the analysis of the end point of β-spectra. Presently two different approaches are followed: the measurement of the tritium β-spectrum using a new generation mass spectrometer by the KATRIN (KArlsruhe TRItium Neutrino) experiment and the calorimetric detection of electrons from ¹⁸⁷Re proposed in MARE (Microcalorimeters Array for a Rhenium Experiment). The MARE detectors are micro-calorimeters running below 100 mK. They are composed by a superconducting rhenium absorber/source, in which the β-events release the energy, and a thermal sensor reading out the temperature variation. Currently TESs (Transition Edge Sensors) and MMCs (Metallic Magnetic Calorimeters) are expected to meet the requirements in term of energy resolution and time constants. We developed MMCs with single crystal Re absorber and paramagnetic Au:Er temperature sensor which are read by SQUIDs with meander shaped sensing inductance. This geometry minimizes the magnetic field in the region of the superconducting absorber and this keeps the trapped flux lines on a negligible level. A detailed analysis of the effects due to the superconducting rhenium absorber is reported, focusing on the influence that superconductive state can have on the detector response.