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TT: Fachverband Tiefe Temperaturen
TT 37: MLT: Poster Session
TT 37.6: Poster
Thursday, March 25, 2010, 14:00–18:00, Poster A
Investigation of mechanical losses in bulk materials for gravitational wave detectors — •Christoph Heilmann1, Daniel Heinert1, Christian Schwarz1, Andreas Tünnermann2, and Paul Seidel1 — 1Friedrich-Schiller-Universität Jena, Institut für Festkörperphysik, Helmholtzweg 5, 07743 Jena, Germany — 2Friedrich-Schiller-Universität Jena, Institut für Angewandte Physik, Albert-Einstein-Straße 15, 07745 Jena, Germany
One of the dominating noise sources in gravitational wave detectors is thermal noise of the optical components. The Brownian motion of the bulk sample’s surface is directly coupled to the mechanical loss of the substrate material.
We present measurements of the mechanical loss for different substrate materials in a temperature range from 5 K to 300 K. Thereby, we focus on monocrystalline samples of calcium fluoride, silicon and sapphire. Silicon – as a low loss material – is the most promising candidate material for the use in gravitational wave detectors. We demonstrate mechanical losses as low as 1.8×10−9 at a temperature of 5.6 K. We present a summary of possible damping mechanisms in the different materials and compare them to the experimental values obtained from our cryogenic loss spectroscopy.
This work is supported by the DFG under contract SFB TR7.