Vibration Isolation Group R. Takahashi (ICRR)Chief T. Uchiyama (ICRR)Payload design H. Ishizaki (NAOJ)Prototype test R. DeSalvo (Caltech)SAS design A. Takamori (ERI)SAS design E. Majorana (INFN)*Payload modeling T. Sekiguchi (ICRR)System modeling * unofficial member LCGT A-review of VIS (29 Nov., 2010)

R&D TAMA-SAS in TAMA One-leg IP in Kamioka Payload and GASF prototype in NAOJ 2011

Disposition of vibration isolation system

Vacuum chamber A) φ2m × (2.5m m cryostat) B) φ2m × 4.3m C) φ2m × 3m Vibration Isolation System A) IP + GASF (3→4 stage) + Payload (cryogenic) B) IP + GASF (2 stage) + Payload (room temp.) C) STACK + Double-pendulum Configuration

iLCGTbLCGT ITMX, ITMY, ETMX, ETMY Type-A IP-GASF + Type-B Payload (25cm, 10kg) Type-A IP-GASF + Type-A Payload (25cm, 30kg) BS, PRM, PR2, PR3, SRM, SR2, SR3 Stack + Type-B Payload (25cm, 10kg) Type-B IP-GASF + Type-B Payload (25cm, 10kg) MC2F, MC2E, PDType-C (10cm, 1kg) Type-C (10cm, 1kg) Configuration

Type-A (old) Support structure of SAS tower is too weak.

Type-B

Type-C

Filter0Filter1Filter2PFIM-MBTM-RM Sensor ACC(H) x3 ACC(V) x1 LVDT(H) x3 LVDT(V) x1 OL x1 PS(H) x3 PS(V) x3 OL x1 PS(H) x3 PS(V) x3 PS(H) x1 PS(V) x1 OL x1 Actuator MC(H) x3 MC(V) x1 MC(Y) x1MC(H) x3 MC(V) x3 MC(H) x3 MC(V) x3 MC(H) x2 MC(V) x2 Motor STEP(H) x3 STEP(V) x1 PICO(Y) x1STEP(H) x2 STEP(V) x2 ACC: accelerometer, LVDT: linear variable differential transformer PS: position sensor, OL: optical lever, MC: magnet-coil, STEP: stepping motor, PICO: picomotor For cryogenic Stepping motor: tested in Rome, 4.8K ok! Position sensor: shadow sensor → fiber sensor Actuator: design taking account of eddy current problem Sensor and actuator

Point Mass Model by R. Takahashi Equation of motion of 8 material points model 8 ｘ 8 stiffness matrix Refer parameters of TAMA-SAS Calculated by MATLAB Type-A (old)

Equation of motion of 9 material points model 10 ｘ 10 stiffness matrix 2-layer structure Calculated by MATLAB Type-A (new) Filter3 + CB

Equation of motion of 7 material points model 7 ｘ 7 stiffness matrix 10kg LIGO mirror Calculated by MATLAB Type-B

Equation of motion of 6 material points model 6 ｘ 6 stiffness matrix Model for Stack is simplified Calculated by MATLAB Type-C

Displacement of test mass The horizontal isolation >3Hz is due to a heat link of 0.03Hz. The vertical isolation is better than the horizontal isolation around 1Hz because of 4 stage GAS filters. Since the final stage (TM) is suspended by 4 sapphire fibers of φ1.8mm, the vertical resonant frequency is about 100Hz. Heat links of 0.03Hz with 1% coupling from vertical mode satisfy demands at 10Hz.

Displacement of each system The isolation of Type-B is better than the isolation of Type-A with heat links >4Hz. When the part of IP-GASF of Type- B is fixed (iLCGT), the isolation of Type-A is worse than the isolation of Type-C with stack >20Hz.

RMS Type-A,B vs. C 0.1 → 2 [  m] x → 2 [  m/s] x20 Integration Hz (Integration 0.1-4Hz)

SimMechanics (The MathWorks TM ) Based on multi body dynamics I)If geometric/topological parameters are determined, equations of motion/transfer functions are obtained almost automatically. II)Direct integration into the Simulink environment. III)How it is calculated is in a black box. Rigid Body Model by T. Sekiguchi

Test Simulation (2D SUS) Triple pendulum suspension system with y, yaw and roll suppressed. Calculated transfer functions (X-X, X-Pitch, X-Z) without geometric asymmetry The parameters (mass, wire length, etc) may be changed easily. Geometric asymmetry may be taken into account. (Now Constructing)

Octopus Octopus is a non-official Virgo tool. The modeling will be used for AdV, but it is not the only model that can be used. It provides (once completed): I) Point-by-point 6x6 matrixes of Force/displacement TFs or displacement ratios. II) Designing tool: several configurations or parameter tuning, within a given configuration can be explored. III) Some add-ons as fitting a dataset of experimental TF and extracting a fit which can be used to extract actual mechanical parameters (…). Rigid Body Model by E. Majorana

This presentation/practical cases. - Often it is useful to show longitudinal/pitch and transversal/yaw sub-matrixes - In the case of LCGT, the Vertical might be more crucial and should be included. Example of outputs of Octopus X Y Z Tx Ty Tz FxFx FyFy FzFz F tx F ty F tz

Schedule

Procedure of installation for ITM/ETM Set IP/GASF （ Tower ） Connection of Dummy mass (200kg+100kg) Embed accelerometers (geophones) Wiring Release Tower Control test (diagonization)2 month for 2 sets Fix Tower Dismount Dummy mass (100kg) Connection of Payload Wiring Release Payload Control test1 month for 2 sets Release Tower / Fix Dummy mass (200kg)