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arXiv · 2508.03468

Mechanical Characterisation of Silicon for the ETpathfinder Test Masses

Guido Alex Iandolo·Alex Amato·Gianpietro Cagnoli·Alessandro Delmonte·Jan-Simon Hennig·Margot Hennig·Sebastian Steinlechner·Janis Wöhler·Stefan Hild·Jessica Steinlechner
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Abstract

The next generation of gravitational-wave detectors, such as the Einstein Telescope, is designed to reduce noise in a wide band of frequencies compared to the current generation, through the use of new technologies. ETpathfinder, designed as an R&D facility for these technologies, is a prototype for which the mirrors were chosen to be made of crystalline silicon, produced by the Leibniz-Institut f\"ur Kristallz\"uchtung. This material choice was made to pave the way for a low thermal noise level at cryogenic temperatures in the Einstein Telescope. This paper shows the mechanical loss of silicon designated to become the test masses for ETpathfinder in the range between room temperature and 53K. In addition, the effect of the anisotropic nature of silicon on the measurement procedure is addressed. Predictions are made of the contribution of the mirror substrate material to the overall ETpathfinder noise budget.

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Guido Alex Iandolo, Alex Amato, Gianpietro Cagnoli, Alessandro Delmonte, Jan-Simon Hennig, Margot Hennig, Sebastian Steinlechner, Janis Wöhler, Stefan Hild, Jessica Steinlechner. 2025-08-05. Mechanical Characterisation of Silicon for the ETpathfinder Test Masses. https://doi.org/10.1103/xzbl-3snb

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