Mechanical loss of a multilayer tantala/silica coating on a sapphire disk at cryogenic temperatures: Toward the KAGRA gravitational wave detector

作者：Hirose Eiichi^*; Craig Kieran; Ishitsuka Hideki; Martin Iain W; Mio Norikatsu; Moriwaki Shigenori; Murray Peter G; Ohashi Masatake; Rowan Sheila; Sakakibara Yusuke; Suzuki Toshikazu; Waseda Kouichi; Watanabe Kyohei; Yamamoto Kazuhiro

来源：Physical Review D - Particles, Fields, Gravitation and Cosmology, 2014, 90(10): 102004.

DOI：10.1103/PhysRevD.90.102004

We report the results of a new experimental setup to measure the mechanical loss of coating layers on a thin sapphire disk at cryogenic temperatures. Some of the authors previously reported that there was no temperature dependence of the mechanical loss from a multilayer tantala/silica coating on a sapphire disk, both before and after heat treatment, although some reports indicate that Ta2O5 and SiO2 layers annealed at 600 degrees C have loss peaks near 20 K. Since KAGRA-the Japanese gravitational-wave detector, currently under construction-will be operated at 20 K and have coated sapphire mirrors, it is very important to clarify the mechanical loss behavior of tantala/silica coatings around this temperature. We carefully investigate a tantala/silica-coated sapphire disk with the new setup, anneal the disk, and then investigate the annealed disk. We find that there is no distinct loss peak both before and after annealing under particular conditions. The mechanical loss for the unannealed disk at 20 K is about 5 x 10(-4), as previously reported, while that for the annealed disk is approximately 6.4 x 10(-4).

• 出版日期2014-11-18
• 单位中国科学院国家天文台