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Published September 22, 2016 | Published
Journal Article Open

Measurement of mechanical loss in the Acktar Black coating of silicon wafers


Some proposed interferometric gravitational wave detectors of the next generation are designed to use silicon test masses cooled to cryogenic temperatures. The test masses will need to be partially coated with high emissivity coating to provide sufficient cooling when they absorb the laser light. The mechanical loss of the Acktar Black coating is determined based on the measurements of the Q-factors of the bending vibration modes of coated and uncoated commercial silicon wafers. The Young's modulus of the coating material is determined using nanoindentation. We use this information to calculate thermal noise of the silicon test masses associated with a high emissivity coating on its lateral side (barrel). It is found that such a coating results in a less than 9% increase of the total strain noise of LIGO Voyager design for a future cryogenic gravitational wave detector.

Additional Information

© 2016 IOP Publishing Ltd. Received 6 May 2016, revised 13 July 2016. Accepted for publication 29 July 2016. Published 22 August 2016. The authors would like to thank Stan Whitcomb for his help, Ian Martin and Peter Murray for the valuable comments, Denis Presnov who made the SEM image of the coating. This work was supported by the Russian Foundation for Basic Research under grant 14-02-00399 and the United States National Science Foundation under grant PHY-1305863. LIGO was constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the National Science Foundation and operates under cooperative agreement PHY-0757058.

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August 20, 2023
August 20, 2023