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Passive Attenuation

Present Superatttenuator performance vs. AdV & ET Requirements S.Braccini for Virgo Suspension group. Passive Attenuation. 2 Hz. Long Pendula. Ground. Resonances. f -2N. Transmission. Frequency (Hz). Soft Springs. Mirror. Magnetic Antisprings. 8 m. Blade Springs.

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Passive Attenuation

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  1. PresentSuperatttenuator performance vs. AdV & ET RequirementsS.Braccini for Virgo Suspension group

  2. Passive Attenuation

  3. 2 Hz Long Pendula Ground Resonances f-2N Transmission Frequency (Hz) Soft Springs Mirror

  4. Magnetic Antisprings 8 m Blade Springs

  5. Rumore Termico Ground Seismic Noise Mirror Seismic Noise

  6. SA design e freccette Filter Chain TF measurements (without Pre-Isolator !)

  7. SA design e freccette CITF Measurements around 2, 4, 9 Hz @ 4.1 Hz < 6 ×10e-8

  8. SA design e freccette CITF Measurements around 2, 4, 9 Hz @ 2.25 Hz 5 ×10e-6

  9. Thermal Noise Measured Upper Limit

  10. DL(f) = h(f) / 3000

  11. TFmax = DL(f) /(LSD Ground Seismic Noise) LSD Ground Seismic Noise = 5 x 10 -7/ f 2

  12. Same Exercise for ET sensitivity

  13. DL(f) = h(f) / 10000

  14. TFmax = DL(f) /(LSD Under-Ground Seismic Noise) LSD Ground Seismic Noise (Kamioka) - 5 x 10 -9/ f 2 (Duzel Mine much better)

  15. Same Exercise for ET-Xylophone sensitivity

  16. DL(f) = h(f) / 10000

  17. TFmax = DL(f) /(LSD Ground Seismic Noise) LSD Ground Seismic Noise (Kamioka) - 5 x 10 -9/ f 2

  18. Valid both for horizontal and vertical seismic noise

  19. High Sens Range Larger stability allows longer measurements

  20. Displacement (m .Hz-1/2) Transfer Function < 10-10 SA design e freccette Top frequency (Hz) Mirror

  21. TF < 1.7 x 10-12 TOP 1.2 x 10-6m Hz-1/2 MIRROR Stressed Measurement T = 41943 s High Sens Range 2 x 10-18m Hz-1/2

  22. TF = 1.26 x 10-11 ! !

  23. AdV ET-Xylophone 1.26 x 10-11 + Pre-Isolator

  24. SA design e freccette SA design e freccette Possible Bypass X-excitation

  25. X - Excitation Results Bypass Indication ?

  26. Red = Line Detected Blue = Line Not Detected Purple = Upper Limit not useful (too large)

  27. Upper Limit Detected 53 113 AdV ET-Xylophone IP Guarantees for this ! Already compliant for ET (Remind that we are speaking of “Upper Limits” Without Pre-Isolator (Just filter chain !)

  28. Vertical TF measurements (Coupling included in the measurement)

  29. Vertical Measurements

  30. Vertical Upper Limit Vertical Detected 60 AdV ET-Xylophone F0 Guarantees for this UPPER LIMIT (!) compliant for ET Without Filter Zero (Just filter chain !)

  31. Preisolator makes safety margin wide in AdV

  32. SA are compliant also for ET starting from 4 Hz.... What happens below?

  33. HORIZONTAL @ 2.25 Hz 5 ×10e-6 Remarkable Attenuation also at 2.25 Hz

  34. VERTICAL @ 2.25 Hz 1.5 ×10e-6 Remarkable Attenuation also at 2.25 Hz

  35. Stage by Stage Measurement (and Model) TF Model Meas. No Maybe Yes 2 3 4 f

  36. ET Design Programme Cut-off 3-4 Hz  No Design Study Cut-off 1-2 Hz  Design Study SCIENCE CASE & NEWTONIAN NOISE TO BE DISCUSSED AT ERICE MEETING

  37. N  1 Hz     2 Hz ------------------------- {3, 1.6*10-7, 5.4*10-10}  {4, 4.8*10-8, 3.3*10-11}  {5, 2.6*10-8, 3.4*10-12}  {6, 2.3*10-8, 6.7*10-12}  {7, 2.1*10-8, 2.6*10-12} Optimized at 1Hz Courtesy G. Cella ~50 m Horizontal G.Cella

  38. Simulations + AnalyticalComputation in progress

  39. Actuation Noise

  40. V V V V 0.2 0.2 Magnet Coil -0.2 -0.2 CavityLength l/100 Locking

  41. M g Inverted Pendulum Flex Joint 30 mHz

  42. Accelerometers DSP DAC Actuators ADC

  43. Motors Sensors Coil Drivers Sensors Coil Drivers Sensors Coil Drivers Superattenuatore • Acc. Sens: • -10-9 m/s2 • 0 – 100Hz • f.s. 1g Control Electronics System Position & Damping • DSP: • 96 bit • - 60 MFLOPs • DAC: • -8 Chan. • 20 bit • 500 KHz • ADC: • -8 Chan. • 16 bit SAR • - 200 KHz

  44. Hierarchical Control

  45. Accelerometers RESIDUAL SWING < 0.1 mm DSP DAC Actuators ADC

  46. MIRRORACTUATION WIND SEA

  47. Tilt

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