Seismic Attenuation System (SAS) for LCGT

Inverted pendulum: 30mHz3 cascaded GAS filter: 500mHzTest mass suspension: triple pendulum

Transfer functions computedwith a rigid body model-20dB @100mHz

V-H coupling dominant @10HzSafety margin of over 50

Seismic Attenuation System (SAS) for LCGTSAS ControlActive Damping of Mechanical Resonances Digital Servo using Commercial Control SystemSensors 3 Horizontal Accelerometers (ACC) 3 Horizontal LVDTs 1 Vertical LVDTActuators 3 Horizontal Magnet-Coil Actuators 1 Vertical Magnet-Coil Actuator

ACC

LVDTActuator

Seismic Attenuation System (SAS) for LCGT

History of SAS R&DInternational collaboration with Caltech and Univ. of Pisa•Started TAMA-SAS study in 2000•R&D of IP and MGAS filter at Caltech by 2001•R&D using SAS prototype at Univ. of Tokyo by 2003•Started manufacturing of SAS for TAMA300 in 2003•Installation of SAS into TAMA300 in 2005

R&D at Caltech

Schedule of TAMA-SAS installation

Seismic Attenuation System (SAS) for LCGT

R&D using 3m FP prototype Isolation of 10-11m/Hz1/2@4Hz RMS velocity of 0.3m/s

SAS prototype in the 3m Fabry-Perot cavity

Seismic Attenuation System (SAS) for LCGT

Test in TAMA300 To 4 Test Masses Installation: 2005 Observation: 2006

SAS for TAMA300