Reduction of thermal fluctuations in a cryogenic laser interferometric   gravitational wave detector
  The thermal fluctuation of mirror surfaces is the fundamental limitation for interferometric gravitational wave (GW) detectors. Here, we experimentally demonstrate for the first time a reduction in a mirror's thermal fluctuation in a GW detector with sapphire mirrors from the Cryogenic Laser Interferometer Observatory at 17\,K and 18\,K. The detector sensitivity, which was limited by the mirror's thermal fluctuation at room temperature, was improved in the frequency range of 90\,Hz to 240\,Hz by cooling the mirrors. The improved sensitivity reached a maximum of $2.2 \times 10^{-19}\,\textrm{m}/\sqrt{\textrm{Hz}}$ at 165\,Hz. 
Takashi Uchiyama, Shinji Miyoki, Souichi Telada, Kazuhiro Yamamoto,   Masatake Ohashi, Kazuhiro Agatsuma, Koji Arai, Masa-Ka...
gr-qc physics.ins-det