1. Advanced SA Specifications & Scientific Motivations S.Braccini, Cascina 21 Settembre 2007

2. Advanced SA Specifications & Scientific Motivations S.Braccini, Cascina 21 Settembre 2007 1) PASSIVE ATTENUATION 2) INERTIAL DAMPING PERFORMANCE & LOCK ACQUISITION 3) INERTIAL DAMPING PERFORMANCE FOR LOW NOISE MIRROR CONTROL

3. 1) PASSIVE ATTENUATION IN THE DETECTION BAND SA Performance vs. Advanced Specifications

4. SA design e freccette Reduce mechanical transmission to make mirror seismic vibrations along the beam below itf noise floor starting from a few Hz

5. SA design e freccette zCorr Top Stage Actuators UPPER LIMITS BOTH VERTICAL AND HORIZONTAL...... Vert Hor

6. VIRGO Thermal Noise Measured Upper Limit VIRGO Thermal Noise

7. HORIZONTAL VERTICAL Upper limits of residual seismic vibrations along the beam are close to the VIRGO thermal noise

8. VIRGO Thermal Noise REPEAT THE MEASUREMENT TO SET UPPER LIMIT BELOW ADV.THERMAL NOISE FLOOR Adv Thermal Noise

10. ADV. frequency(Hz) VIRGO Sensitivity AdV Sensitivity Linear Spectral Density h (Hz -1/2 )

11. HORIZONTAL VERTICAL 6 x 10 -18 m Hz -1/2 OLD RESULTS VERY CLOSE TO VALIDATE SA FOR ADVANCED

12. It is possible to improve upper limit since the itf is much less noisy A few 10 -13 m/Hz 1/2 (CITF)

13. It is possible to improve upper limit since the itf is much less noisy (VSR1) A few 10 -16 m / Hz 1/2 @ 10 Hz (Neglect calibration not well known) (CITF) A few 10 -13 m / Hz 1/2 @ 10 Hz (Neglect calibration not well known)

14. ......................... Obvious Conclusions........ IMPROVE UPPER LIMIT AT 4-10 Hz REGION IS STRAIGHTFORWARD

15. ......................... Obvious Conclusions........ IMPROVE UPPER LIMIT AT 4-10 Hz REGION IS STRAIGHTFORWARD POSSIBLE EXTENSION TO HIGHER FREQUENCY.....

16. SA attenuation is already good for Advanced ?

17. YE S FILTER CHAIN DESIGN IS FROZEN

18. SA attenuation is already good for Advanced ? YE S FILTER CHAIN DESIGN IS FROZEN NO (Very Unlikely) NEW TASK

19. 2) MIRROR SWING DAMP FOR LOCKING ACQUISITION ID Performances vs. Adv. Specifications

20. Mirror swing is damped enough by ID so to make permanence time on resonance long enough to acquire lock?

21.   Mirror swing is damped enough by ID so to make permanence time on resonance long enough to acquire lock? Photodiode demodulated signal during resonance crossing

22. Dynamical limit F orce_max  T > m  v = m v  T > m v / F orce_max Band limit  T > 1 / UGF Ringing  T >  s  > Max[ 1/UGF,  s, mv/F max ] 100-200 Hz L/c x F/  Now 40 mN NOTE: THE LINEARIZATION FACTOR MAKES THE CROSSING AREA A FEW nm WIDE

23. ARE PRESENT MAGNETS COMPATIBLE WITH ADVANCED VIRGO ?

24. B = (B x, B y, B z )‏ Field Noise Gradient Noise Newton Amp. m 2 T/m ARE PRESENT MAGNETS COMPATIBLE WITH ADVANCED VIRGO ?

25. Gradient spectrum flat (10 Hz - 1 kHz): 5 - 50 (pT/m) Hz -1/2 Peak at 50 Hz with typical rms values between 1 and 10 nT/m. 0.05 0.12 A m 2 for 4 magnets VIRGO attuale 50 Kg R.Schofield et al. LIGO Vacuum Chamber Pole Gradient Noise

26. g = 0.05 (Residual dipole percentage) m = 40 kg (mirror mass)  = 4 x 0.03 A m 2 (4 magnets dipole) Gradient noise LSD = 50 (pT/m) Hz -1/2 Factor 2 to keep into account 4 mirrors Gradient Noise m Hz -1/2

27. Gradient Noise Linear Spectral Density h (Hz -1/2 ) frequency(Hz)

28. Gradient Noise frequency(Hz) Linear Spectral Density h (Hz -1/2 )

29. Gradient Noise frequency(Hz) Linear Spectral Density h (Hz -1/2 )

30. Field Noise B D Field spectrum flat (5 Hz - 200 Hz): 10 -11 -10 -10 T/Hz 1/2 Peak at 50 Hz: rms value of a few nT

31. Field Noise B D 4 Mirrors x 2 Axis (Bx and By) (Uncoherent sum) x Tower Pole D = 0.001 m g = 0.05 (LIGO 0.02) mu = 0.12 Am2 (0.3 for each) I = 0.15 kgm2 By=10-10 T Hz-1/2 FACTOR SQRT(8): 4 Mirr + 2 Axis IDENTICAL FORMULA BUT DEPENDS ON MIRROR-BEAM CENTERING

32. Dynamical limit F orce_max  T > m  v = m v  T > m v / F orce_max Band limit  T > 1 / UGF Ringing  T >  s  > Max[ 1/UGF,  s, mv/F max ] L/c x F/  100-200 Hz nm / v A few mN (Vincenzo's talk) MAGNET REDUCED BY A FACTOR 30

33. Dynamical limit F orce_max  T > m  v = m v  T > m v / F orce_max Band limit  T > 1 / UGF Ringing  T >  s  > Max[ 1/UGF,  s, mv/F max ] L/c x F/  100-200 Hz nm / v v <a few 10 -7 m/s v < a few 10 -6 m/s

34.  m/s  mHz -1/2 /s rms around 10 -7 m/s

35. IT SHOULD BE ENOUGH BUT A SIMULATION IS NECESSARY

36. IT IS RULED BY LOCAL TOP STAGE MOTION IT SHOULD BE ENOUGH BUT A SIMULATION IS NECESSARY

37. 3) MIRROR SWING DAMP FOR LOW NOISE CONTROL ID Performances vs. Adv. Specifications

38. Next argument is indipendent of the magnet choice.... Let us start from the Status Quo

39. MESSAGE 1 - The entire dynamics of the marionetta motion is in the freq.range 0-300 mHz. MESSAGE 2 – Windy days affect 0-100 mHz region (tilt?) MESSAGE 3 – All comes from the top

40. mm  mHz -1/2

41. MESSAGE 4 – We are not using all dynamics on Marionetta

42. Linear Spectral Density h (Hz -1/2 ) frequency(Hz) WITH PRESENT SET-UP AND MSC

43. Linear Spectral Density h (Hz -1/2 ) frequency(Hz) WITH PRESENT SET-UP AND MSC

44. Linear Spectral Density h (Hz -1/2 ) frequency(Hz) WITH PRESENT SET-UP AND MSC

45. CONCLUSIONS PASSIVE Chain attenuation is “almost” validated for Advanced (new test)

46. CONCLUSIONS PASSIVE Chain attenuation is “almost” validated for Advanced (new test) LOCKING Mirror Magnet Dipole has to be reduced by a factor 30 Not terrible for locking acquisition (but simulation necessary)

47. CONCLUSIONS PASSIVE Chain attenuation is “almost” validated for Advanced (new test) LOCKING Mirror Magnet Dipole has to be reduced by a factor 30 Not terrible for locking acquisition (but simulation necessary) NOISELESS CONTROL (argument independent on magnets) Payload swing is totally between 0-300 mHz, ruled by top seism Swing has to be reduced by a factor 60 with the present set-up

48. CONCLUSIONS PASSIVE Chain attenuation is “almost” validated for Advanced (new test) LOCKING Mirror Magnet Dipole has to be reduced by a factor 30 Not terrible for locking acquisition (but simulation necessary) NOISELESS CONTROL (argument independent on magnets) Payload swing is totally between 0-300 mHz, ruled by top seism Swing has to be reduced by a factor 60 with the present set-up This justify all our future: 1) VIRGO+ New Electronics 2) VIRGO+ MSC Activities (Filter 7 reallocation, tidal, etc.) 3) R&D on Tiltmeters-Piezo to reduce swing below 100 mHz 4) Accelerometers Noise to reduce swing below 100 mHz 5) Increase loop gains to reduce swing at higher freq (R&D on New F0, New IP)