Investigation of Mechanical Properties of Cryogenically Treated Music Wire

TL;DR

This study investigates whether cryogenic treatment improves the mechanical properties of music wire used in gravitational wave detectors, finding no significant differences in properties like mechanical loss and breaking strength.

Contribution

The paper provides an experimental comparison of untreated and cryogenically treated music wire, specifically assessing properties relevant to gravitational wave detector suspensions.

Findings

No significant change in mechanical loss

No significant change in breaking strength

Cryogenic treatment does not enhance wire properties for this application

Abstract

It has been reported that treating music wire (high carbon steel wire) by cooling to cryogenic temperatures can enhance its mechanical properties with particular reference to those properties important for musical performance. We use such wire for suspending many of the optics in Advanced LIGO, the upgrade to LIGO - the Laser Interferometric Gravitational-Wave Observatory. Two properties that particularly interest us are mechanical loss and breaking strength. A decrease in mechanical loss would directly reduce the thermal noise associated with the suspension, thus enhancing the noise performance of mirror suspensions within the detector. An increase in strength could allow thinner wire to be safely used, which would enhance the dilution factor of the suspension, again leading to lower suspension thermal noise. In this article we describe the results of an investigation into some of the mechanical properties of music wire, comparing untreated wire with the same wire which has been cryogenically treated. For the samples we studied we conclude that there is no significant difference in the properties of interest for application in gravitational wave detectors.