Measurement of mechanical loss in the Acktar Black coating of silicon wafers. (22nd August 2016)

• Record Type: Journal Article
• Authors: Abernathy, M R; Smith, N; Korth, W Z; Adhikari, R X; Prokhorov, L G; Koptsov, D V; Mitrofanov, V P
• Is Part Of: Classical and quantum gravity. Volume 33:Number 18(2016:Sep.)
• Publication Date: 2016-08-22
• Subjects: interferometric gravitational-wave detectors -- high-emissivity coating -- mechanical loss -- silicon test mass; Quantum gravity -- Periodicals; Gravitation -- Periodicals; Relativity (Physics) -- Periodicals; Space and time -- Periodicals; Periodicals; 521.1
• DOI: 10.1088/0264-9381/33/18/185002
• Languages: English
• ISSNs: 0264-9381

Abstract

Abstract: 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.