Commissioning status and plans ILIAS - June 14 th 2005 Matteo Barsuglia

1. Commissioning status and plans ILIAS - June 14th 2005Matteo Barsuglia 1/ what happened in the last month 2/ New sensitivity: a preliminary noise budged and next steps 3/ Jumps investigations 4/ Plans for the next 6 months

2. 1/ What happened in the last month

3. C5 sensitivity (Dec 2004) C4, recombined 7W input power C5, Recycled 0.7 W input power

4. May 17th: realignment of B5 (rec beam photodiode) • ‘detection’ mode • DARM controlled with Asy_phase • CARM with rec_phase • MICH with rec_quad • PRC with refl_3f_phase Asy_phase rec_quad ref refl_3f_phase B5 photodiode (rec beam) Laser frequency rec_phase

5. Minirun M3 – may 19th Proper minirun M3 Restoring C5 science mode

6. Comparison with M2 – May 5th

7. Jumps during M3 ~5 jumps

8. Sensitivity on May 20th C5 sensitivity • Roll-off Michelson at 50 Hz (100 Hz during C5) • LO board upgraded • Local control upgraded

9. Michelson roll-off @ 50 Hz 1/ Elliptic roll-off at 50 Hz unity gain frequency at 6-7 Hz

10. May 19th-26th: a good week ‘ no jumps’

11. May 23rd sensitivity • Low noise coil drivers on arm mirrors (1/25)

12. Marionetta and tidal control • Marionetta and tidal control tested with recycled interferometer • Residual correction seems to be compatible with Virgo specifications f < 10 mHz Recycled ITF internal power Force on marionetta Force on mirror 10 mHz < f < 10 Hz f > 10 Hz

13. May 27th, Jumps again Some locks with jumps some locks without jumps Injection realignment realignment quadrant mode-cleaner Work on NI vertical damping ITF relocked 50’

14. 50’ lock on Thursday evening Power fluctuations maybe higher than normal No evident jumps

15. May 27th, Jumps again Some locks with jumps some locks without jumps Injection realignment Only work: realignment quadrant mode-cleaner Work on NI vertical damping ITF relocked 50’

16. Friday May 27th , the bad Zoom on a jump bench of the first plot

17. Friday 27th, the good

18. Friday 27th , the good New sensitivity curve (with BS coils drivers x4 resistors) – obtained during one of the “good” locks • with resistors x4  BS and arm mirrors should contribute at the same level Zoom on the 50-100 Hz region

19. Sensitivity evolution May 27th

20. Last week

21. photodiode centering checks May 30th - June 1st • Photodiodes B1p, B5, B5_2f, B2_3f • PR-NI configuration • other mirrors misaligned by 10 mRad • maximize AC or DC signal • Photodiodes B8 • North cavity configuaration • other mirrors misaligned by 10 mRad • maximize DC signal All photodiodes were found centered

22. June 1st: demod phases checks • Demod phases (with respect to May 17th) • B2_3f –170-150 (maximizing P/Q for a line on PR using the CITF) • B5_2f –43-23 (maximizing sideband crossing, using the CITF) • B5 –34-28 (minimizing frequency noise on Acq, using north cavity only) • B8 OK (minimizing frequency noise on Acq, using north cavity) • Are the tuning criterions right ? • Why these phases changes?

23. M4 – changes in B2_3f_phase -110 -150 (“good” phase)

24. M4 – new BS local controls

25. Improvements in low frequency sensitivity – june 3rd - Black = may 27th (+ x4 resistors on BS) - red = June 3rd (+ new controls on BS and gain decreased by factor 2 on WI and NI)

26. Sensitivity evolution – low freq C5 June 3rd

27. 2/ Sensitivity: a preliminary noise budget and the next actions

28. sensitivity curve electronic noise (shutter closed) shot noise Virgo nominal sensitivity Sensitivity – high frequency (Input power = 0.7 W) C5 May 2005 Phase noise x 4 x 40

29. Phase noise measurements ACp noise (>5000 Hz) M3 data • During C5: •  = 0.48 rad/Hz • Now: •  = 0.39 rad/Hz • No big improvement on  But a big reduction of B1_ACq!  Improvement of local controls? Volts/sqrt(Hz)  = 0.39 rad/Hz ACq signal (0-100Hz) Volts C5 May 27, 2005 29

30. Power fluctuations Internal power (rescaled) Dark fringe power (W) Contrast 1 mW / 20 W ~ 5e-5

31. ? What is the bump? ACp noise (1600-3000 Hz) Volts/sqrt(Hz) Volts ACq signal (0-100Hz) 31 => The amplitude of the bump does not vary with B1_ACq like phase noise

32. High frequency: actions • Oscillator phase noise • Several parallel solutions: • Local oscillator distribution electronics replaced • Main oscillator to be replaced market evaluation on going • Prototype for active compensation of the ‘wrong’ quadrature (ASI servo a la LIGO) ready to be tested • Linear alignment should help to reduce the ‘wrong’ quadrature • When oscillator phase noise is killed •  limit will be (?) by electronic and shot noise  change injection bench  power x10 • Electronic noise constant • Shot noise scales as • Still factor 5 missing with respect to the design (1 kW on BS) • Increase transmission of the mode-cleaner (now 50%) • Increase PR reflectivity planned 0.920.95

33. Sensitivity: low frequency • Coherence with auxiliary degrees of freedom control noises (PRC and MICH) • Coherence with BS angular control signals • The signals are coherence each others: need cross-coherence computation to identify the individual components May 23rd and 25th

34. Sensitivity: low frequency Individual contributions BS_zCorr BS_txCorr PR_zCorr BS_zCorr 20 40 50 Hz

35. Sensitivity: decrease angular noises June 01 (M4) & May 25 The coherence between B1_ACp and BS (tx, z), PR (z) correction is reduced  the 3 channels are coupled and BS_txCorr was the main source of the noise Now, B1_ACp coherent with WI_txCorr 35

36. Low frequency: actions • Local controls: • They will be switched off when automatic alignment will work : wait to commission the automatic alignment • Small improvements on going • Actuators noise: • Low noise coils driver (1/25) don’t limit the sensitivity • on BS (1/4)  same level that the arm mirrors • Auxiliary degrees of freedom • Roll-off optimization (now at 50 Hz) • Analysis of the noise source and propagation • Non diagonal driving matrix elements

37. Reduce the control noises

38. Reduce the control noises • Alreay tested in LIGO

39. Reduce the control noises: simulation • Siesta simulation • Influence of the BS noise in the low frequency part of the spectrum • Tentative of suppression through addiction of non-diagonal terms in the driving matrix No reduction Perfect TF 15% error in the TF

40. 3/ Jumps investigations: ideas and next actions

41. Jumps – some ideas • Optical defect: • Clipping from IB mirrors • Beam quality not enough • Bad management of the secondary beams from BS at the injection level • Clipping, stry light from BS • … • Coupling with global alignment (I.e. Anderson effect) • Locking problem (I.e.bad setting of the demodulation phases) • Electronic hidden problem • Problem related with the ITF parameters (I.e. recycling cavity flat-flat) Why sometimes (~ week) it works very well?

42. 0/ What was done in the last month • Stray light hunting widely done on the reflected beam • Realignment of photodiodes: • Establishment of a check procedure based on simple optical configuations (power recycling – north input cavity, north cavity) • Monitoring of the photodiode position through CCD cameras (not on all the beams) • Experiments to understand the relationships between jumps and mirror misalignments • put low frequency lines on all the mirrors, at 8% (lock more robust)

43. Jumps vs mirrors alignment May 20th data, 8 % “jumped” state Standard state Mirrors angle combination • If confirmed at the dark fringe can be an indication of an optics defects (clipping, stray light..)

44. 1/Injection realignment: may 26th Some locks with jumps some locks without jumps Injection realignment Only work: realignment quadrant mode-cleaner Work on NI vertical damping ITF relocked by Vincenzo 50’

45. 1/Injection re-alignment: history • One of the local control laser of the injection system was almost dead (power 40% less than normal) • This laser is one of the angular references of the bench (the “fine” mode) • During the replacement the reference becomes a CCD camera (the so called “rough mode”) • Differences between the rough mode and the fine mode can makes differences in the injection bench position • Once the new laser is installed the beam is aligned with respect to the reference cavity, attached at the bench • The mode-cleaner is re-locked, and the beam incoming in the interferometer is realigned through picomotors after the mode-cleaner

46. 1/Injection re-alignment: actions • Find some indications of how the injection bench has moved with respect to the original position (I.e.how much we should move the picomotors after the mode-cleaner to realign the beam at 3 km) • Try to reconstruct the injection bench rotation (300 microrad in the interferomter plane) • Move the injection bench in the inverse direction (today) and re-align the beam consequently • Re-lock the interferometer • If necessary, make a further scan

47. 1/Injection re-alignment: future • 2 new features: • BMS: beam monitoring system: a reference (on the ground) for the beam alignment • The beam is aligned with respect to the mode-cleaner dihedron

48. 2/ Beam splitter stray light

49. 2/ Beam splitter stray light

50. 3/ Fringes on the north&west cavity reflected beams • seen also on west cavity (same fringes) • from the input beam ? • from input mirrors AR ? North cavity well aligned (PR, WI misaligned by 10 millirad, WE misaligned by 500 microrad)