Payload design methods versus modeling E. Majorana

PAY versus Suspension – 1, passive  L = h * 3000 m TF max =  L/x seism Ground seismic noise at Virgo site : x seism = 5 x / f 2 Braccini, Jul09

PAY versus Suspension – 2, active Braccini, Jul09 Reduction factor 3-4 Wind (5%) 7-8 Calm (95%) Direct Meas. Now Calm Wind AdV

The suspension will not be critically modified.

PAY versus AdV layout PAY changes will be driven essentially by: - Thermal noise issues - New optical layout

Baseline approach

- The overall approach is that of exploiting the know how and the experience. - Expectedly last stage suspension optimization (control operation and thermal noise) is easier for single-mirror payloads. This idea drove the PAY baseline.

MiniPayload: Mar: motor/coils Mir: coils Functions: DC,LC,LOCK,AA StdPayload: Mar: motor/coils Mir: coils Functions: DC,LC,AA(?) Note: NoRMPayload option ? NoRMPayload: Mar: motor/coils Mir: coils (?) Functions: DC,LC Baseline (a possible solution) StdPayload hung to Intermediate mass (IM): IM: motors/coils, controlled versus F7 F7damping needed (at least during initial lock states) Mar: motor/coils Mir: coils Functions: DC,LC,LOCK(no reallocation),AA IM Majorana ISC IB susp BS susp

Majorana ISC Baseline solution will be subject to - further OSD validation but ALSO, - PAY simulation Overall transfer functions (SA+PAY) Electro-mechanical parameters What is still needed ISC check

OSD2 OSD4 The same study can be performed for other solutions (baseline is OSD2) 0-order outcome: translation and angular TF Top-stage  PR/SRM2 and  BS or IMx translation and angular TF BS(RM) or IMx(MAR) actuation  PR/SRM2 translation and angular TF PR/SRM2  BS or IMx marionette verifying the need of further controlled intermediate masses actuation couplings RP couplings suspension behavior controllability

Payload design method OSD layouts PAY solutions: - know how - commissioning experience PAY solutions: - know how - commissioning experience PAY simulation + ISC check PAY simulation + ISC check OK AdV payloads

PAY simulation kick-off Marionetta (110 kg) “OCTOPUS” (P. Ruggi) as analytical modeling tool to improve single mirror payloads already started in the context of V+. I)Overall model consistency check VS experiment II)Model used to deduce with accuracy input parameters of the prototype III)Model used to design prototype modifications

Monolithic payload prototype tests HYBRID STEEL FULL

Example of TF meas results / model Longitudinal (z) Mirror OL response VS Mario exc Longitudinal (z) Mirror OL response VS Mirror exc Yaw (  y ) Mirror/Mario OL response VS Mario exc

Example of TF meas results / model Yaw (  y ) Mirror OL response VS Mirror exc Pitch (  x ) Mirror/Mario OL response VS Mario exc Pitch (  x ) Mirror OL response VS Mirror exc

Example of TF meas results / model Tuned parameters for lumped-impedance matrix model vertical (y) Mario Accel response VS Mario exc 7 7 model TF meas FIT check seed/tuned Param model driven design y n

A further check of the modeling process and possible payload optimization microseism due to sea activity is often active in the range Hz Effective attenuation of  seism at the payload Thanks to IP inertial damping and suspension performance the lock force applied to the marionette corrects the residual payload motion, whose rms above 100 mHz is ~ 1 order of magnitude smaller than the ground motion (MSC,Hannover ) Pitch (in present payload): g=-88 urad/V (DC); cp=[ ] cz=[ ] cp=[ ] cz=[ ]cp=[ ] cp=[ ] sp=10 Murphy law: Virgo suspension chain and actual payloads have z/p couples in the same range, which falls in the microseismic band=> pitch alignment suffers …

+2. 7 mm mm +7.8 mm Barycentre move tests in monolithic payload configurations I,IIa,IIb Maraging wire clamp and fibre  baricentre 4.85 kg steel inserts used to rise up artificially the barycentre Meas/Model check The clean way to drive pitch mode in the range mHz, reducing z/p couple impact on pitch control accuracy is to bring the bending point of marionette wire closer to the barycentre kg kg

1)Model reproduces the effect and consistent; 2)full simulation of the suspension chain will predict overall passive TFs and active setup will be studied; 3)actual payload design requires fine tuning 1)Model reproduces the effect and consistent; 2)full simulation of the suspension chain will predict overall passive TFs and active setup will be studied; 3)actual payload design requires fine tuning

Outcome in V+ design: adjustable marionette suspension point Marionette section Next use of OCTOPUS: before suspending the payloads it is crucial to check the model of the overall suspension. Marionette bending point tunable on the barycentre

CONCLUSIONS - PAY simulation tool even if not released as stable SW package does exist. - Simulation of modified single-mirror payload (V+) has to be completed by Nov/Dec NDC multi-mirror payloads will be studied in order to compare reasonable mechanical solutions for OSD 2 and 4 by Feb/March 09.