Direct measurement of thermal fluctuation of high-Q pendulum.
We have achieved a direct measurement of the thermal fluctuation of a pendulum in an off-resonant and wide frequency region using a laser interferometric gravitational-wave detector. These measurements have been well identified for over one decade by an agreement with a theoretical prediction, which is derived by a fluctuation-dissipation theorem. Thermal fluctuation was dominated by the contribution of resistances in coil-magnet actuator circuits. When we tuned these resistances, the noise spectrum also changed according to a theoretical prediction. The measured thermal noise level corresponds to a high quality factor on the order of 10(5) of the pendulum.
Agatsuma
Kazuhiro
K
Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan. agatsuma@icrr.u-tokyo.ac.jp
Uchiyama
Takashi
T
Yamamoto
Kazuhiro
K
Ohashi
Masatake
M
Kawamura
Seiji
S
Miyoki
Shinji
S
Miyakawa
Osamu
O
Telada
Souichi
S
Kuroda
Kazuaki
K