Speaker
Description
Future gravitational wave detectors such as the Einstein Telescope and Cosmic Explorer will require cryogenic mirror suspensions with thermal noise significantly below the limits of current fused silica systems. Crystalline silicon is a leading candidate material due to its high mechanical quality factor and favourable thermal properties. Silicon suspension development requires suitable silicon fibres to be produced and experimentally validated.
Here we present the first float-zone monocrystalline silicon fibres produced for gravitational-wave detector suspensions by the Leibniz-Institut für Kristallzüchtung, together with an extensive characterisation of their structural, mechanical, and thermal properties. We report the crystal orientation, material purity, diameter uniformity, and mechanical strength of the fibres. Mechanical loss measurements are performed to assess intrinsic dissipation and expected thermal-noise performance, while thermal conductivity measurements evaluate their suitability for cryogenic heat extraction from suspended test masses.
Together, these results provide the first comprehensive experimental assessment of silicon fibres for gravitational-wave detector suspensions. Using the measured material properties, we present a thermal-noise model demonstrating their potential viability for Low Frequency Einstein Telescope suspensions, marking an important step toward crystalline suspension technology in next-generation gravitational wave detectors.