Potential mechanical loss mechanisms in bulk materials for future gravitational wave detectors

TL;DR

This paper analyzes mechanical loss mechanisms like Akhieser and thermoelastic damping in bulk materials, providing models to optimize materials for future gravitational wave detectors by reducing thermal noise.

Contribution

It offers a combined analytical and numerical approach to quantify damping mechanisms in materials like quartz and silicon across a wide temperature range.

Findings

Akhieser and thermoelastic damping can explain low-temperature loss in quartz.

Thermoelastic damping is not dominant in bulk silicon from 10 K to 300 K.

Numerical models successfully estimate thermoelastic noise in large silicon test masses.

Abstract

Low mechanical loss materials are needed to further decrease thermal noise in upcoming gravitational wave detectors. We present an analysis of the contribution of Akhieser and thermoelastic damping on the experimental results of resonant mechanical loss measurements. The combination of both processes allows the fit of the experimental data of quartz in the low temperature region (10 K to 25 K). A fully anisotropic numerical calculation over a wide temperature range (10 K to 300 K) reveals, that thermoelastic damping is not a dominant noise source in bulk silicon samples. The anisotropic numerical calculation is sucessfully applied to the estimate of thermoelastic noise of an advanced LIGO sized silicon test mass.