ICRR M2 Takanori Sekiguchi ICRR, NAOJ A, ERI B, Sannio Univ. C, INFN Roma D, NIKHEF E, AEI F Ryutaro Takahashi, Kazuhiro Yamamoto, Takashi Uchiyama, Hideharu Ishizaki A, Akiteru Takamori B, Riccardo DeSalvo C, Ettore Majorana D, Eric Hennes E, Jo van den Brand E, Alessandro Bertolini E,F, Masatake Ohashi, Kazuaki Kuroda, LCGT Collaboration JGW-G

2012/3/24The 67th Annual Meeting of JPS2  Top part of KAGRA-SAS Pre-Isolator 1. Vibration Isolation at a low frequency (< 0.1 Hz) * Attenuate the mirror oscillation at the micro- seismic peak (0.2~0.3 Hz) 2. Control the position and orientation of the system  Role of Pre-isolator

2012/3/24The 67th Annual Meeting of JPS3 GAS Filter ・ Vertical attenuation Inverted Pendulum ・ Horizontal attenuation Position Sensor (LVDT) Coil-magnet actuator ~1.2 m Accelerometer

2012/3/24The 67th Annual Meeting of JPS4 GAS Filter Inverted Pendulum

2012/3/24The 67th Annual Meeting of JPS5  Performance measurement of GAS Filter, vertical LVDT, coil-magnet actuator

2012/3/24The 67th Annual Meeting of JPS6  Radially arranged cantilever springs  The horizontal force works as an anti- spring and reduces the resonant frequency of the filter  In principle the frequency can be reduced to zero. Restoring force Anti-spring force Compression

2012/3/24The 67th Annual Meeting of JPS7  The resonant frequency of the filter is measured, tuning the load weight and the blade compression.  Using Mercury 2000 (MicroE systems) as a displacement sensor Load ~320 kg Photo sensor Scale

2012/3/24The 67th Annual Meeting of JPS8 Load Increases

2012/3/24The 67th Annual Meeting of JPS9  Non-touching displacement sensor  10 kHz modulation  The voltage induced at the two receiver coils depends on the position of the primary coil.

2012/3/24The 67th Annual Meeting of JPS10 Micrometer Residual [mV]

2012/3/24The 67th Annual Meeting of JPS11 ~ Hz  As sensitive as TAMA- LVDT  Limited by the noise from the electric circuit (driver)

2012/3/24The 67th Annual Meeting of JPS12 LVDT Coil-Magnet Actuator ∝ f -2  Random input signal to the actuator  Transfer function from the actuation force to the LVDT signal  With the digital system

2012/3/24The 67th Annual Meeting of JPS13 Actuator Input Signal LVDT Output  When the actuator is driven by a high frequency signal (> 2 Hz), the LVDT shows a non-linear response.  The same phenomenon is observed even when the magnet for the actuator is eliminated.  Magnetic field couplings??

2012/3/24The 67th Annual Meeting of JPS14  Performance measurement on the GAS filter, LVDT and actuator of the pre-isolator prototype  The top filter can be tuned at ~ 0.2 Hz, and maybe even lower.  The linear signal is observed in LVDT over a range of ~1 cm.  Non-linear couplings between the actuator and LVDT.  Tuning the top filter at lower than 0.1 Hz, and the Q-factor, hysteresis, stability are checked.  Investigating the cause of the actuator-LVDT couplings  Control test with the inverted pendulums

2012/3/24The 67th Annual Meeting of JPS15

2012/3/24The 67th Annual Meeting of JPS16

2012/3/24The 67th Annual Meeting of JPS17 Chunk 1 Chunk 2 Chunk 3 Chunk 4  Divide a ring-down signal to many chunks. The signal in each chunk is fit by the following function  Investigating amplitude (A) dependence of the Q-factor (Q=π*f*τ)

2012/3/24The 67th Annual Meeting of JPS18  Q-factor increases when the amplitude decreases  Explained by the dissipation controlled by Self-Organized Criticality (SOC)

2012/3/24The 67th Annual Meeting of JPS19  Linear encoder Mercury 2000 (Micro E systems)  Resolution: 80 nm Photosensor Scale

2012/3/24The 67th Annual Meeting of JPS20