Evaluation of BS and RM noise arisen from the AC component of geomagnetism field

Viewable by:

Modifiable by:

Other Versions:

JGW-T1503469-v1
09 Apr 2015, 19:20

Abstract:: In order to lock phase shift, some magnet attaches to the mirror of KAGRA interferometer. In these kind of mirror, the beam-splitter (BS) and the recycling mirror (RM) is plan to attach 4 magnets. Although these magnets is indispensable for interferometer, the displacement motion of mirror is arisen from the vibration of attached magnet since the fluctuation of geomagnetism field affects the magnetic dipole moment of a magnet and vibrate the mirror though the motion of magnet. This motion of mirror (in this article, we call this kind of noise as “magnetic noise”) is critical noise source of KAGRA interferometer. In this article, we report that the explanation how the magnetic noise is arisen and the result of simulation how much the upper-limit of magnetic noise of BS and RM is. In the result of simulation, we show that the upper-limit of magnetic noise of BS and RM is fulfill KAGRA requirement except for Signal recycling mirror. However the magnetic noise of Signal recycling mirror can be archived to the requirement of KAGRA under more realistic condition.