1. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Analysis of noise in VIRGO

2. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 l What we mean for “noise analysis” l How is the noise analysis work organized in Virgo l Which tools l Noise and data analysis groups l What has been done l Some results in noise identification l Sensitivity curve debugging (noise understanding)

3. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 What we mean for noise analysis l VIRGO commissioning:  interferometer still in a development phase  the Interferometer’s configuration is progressively upgraded l The sensitivity is measured through the output signal calibration l We try to identify the different sources of the noises l We try to upgrade things in order to reduce the identified noise source

4. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Work organization l Engineering runs: allow collection of data (3-5 days every 2 months) l Data Analysis: division in investigation groups (normally 3-4 persons with a coordinator) l Discussion of the results in data analysis meetings l Depending on the results, the further activity is decided (implementations, modifications, etc.)

5. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Summary of the performed activity l CITF (2000-2002):  Five engineering runs (E0-E4)  About 5-10 investigation groups  About two meetings after each run l VIRGO (2003-now):  Four Virgo runs up to now (the last at the end of June)  About 10 investigation groups  Normally one preliminary meeting short after the run, then a more detailed one http://wwwcascina.virgo.infn.it/commissioning/Eruns.html

6. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Engineering runs l 4 VIRGO Engineering runs (C1-C4, now five days each)  C1 (14-17 November 2003): North Arm locked  C2 (20-23 February 2004) : North Arm locked+linear alignment; West Arm locked  C3 (23-27 April 2004) : North Arm locked+linear alignment+second stage frequency stabilization; Recombined locked (lock acquisition mode, no linear alignment)  C4 (24-29 June 2004): Recombined+linear alignment on both arms+second stage frequency stabilization

7. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 VIRGO sensitivity curve

8. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Progress in sensitivity

9. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Investigation groups l Individuated investigation groups: (http://wwwcascina.virgo.infn.it/DataAnalysis/Noise/)  Present list of the groups: –Calibration –Locking performances and noise –Alignment performances and noise –Suspension control performances and noise –Environmental noise –Laser noise –Glitches search and identification –Lines identification –Quantify noise stationarity/gaussianity –Readout noise

10. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Tools l Data are in the Common Data Frame Format for Interferometric Gravitational Wave Detectors Mostly handled with: l dataDisplay:data visualization and analysis l Siesta:simulation vs data l Vega:data visualization and analysis l Other (personal) softwares and/or libraries

11. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 dataDisplay dataDisplay: Virgo software for visualizing and analyze data l It is the most commonly tool used by commissioning people. l It allows on-line (in-time) data analysis and visualization l It allows visualization of measured and simulated data l It has ist own routines for analysis (FrVect: offsets, sum, multiplication, FFT, coherence,TF, etc.)

12. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Siesta Siesta: Virgo software for simulation l C written code with C input cards l It allows the simulation of the whole interferometer (optics, mechanics, etc.) in the time domain l It has its own routines for analysis (FFT, coherence, TF, …) l It allows simulation of control loops: simulated data in frame format can be compared with the measured ones (e.g. with dataDisplay)

13. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 VEGA VEGA: Graphical software, based on ROOT (Cern), modified to handle data in the Frame format (Frame library and FrVect) Allows off-line data visualization and analysis l Less used by commissioning people than dataDisplay l It is linked to the Cernlib libraries for data analysis

14. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Others Many people working in noise analysis have developed their own routines and libraries (Matlab, C and C++ software). Some examples: l Lines identification: Florence-Urbino l Non-linear, non-stationary: Nice, Urbino l Lines removal: LAPP l Whitening: EGO

15. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Common library Since there is much dispersion, discussion is going on in Virgo in order to create a common library for noise (and data) analysis. For the moment no final common reference software has been established yet

16. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Examples of noise investigation

17. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Environmental sensors 3km Central building MC End b. West End b. North End b. Low Frequency Accelerometers Tri-axial, 0.2-200 Hz (Kinemetrics - “Episensors”) High Frequency Accelerometers Vertical Piezo, 10-10000 Hz (Bruel&Kjaer) Other Environmental probes: Microphones Magnetometers Pressure probes Humidity Temperature Weather station

18. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 LF seismic activity monitoring Episensor (tri-axial accelerometer) in the central Building Updated on web each 10 minutes Sea activity Human activity (road traffic on highway bridges) Human activity around the site

19. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Acoustic noise in the detection laboratory

20. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C1 (North Arm) Electronic noise Shot noise MC length control noise MC length noise Mirror control noise

21. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C2 (North Arm) Shot noise ADC noise MC length control noise MC length noise

22. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C2: spectrogram 150 Hz-3 kHz Decrease of noise Noise is higher than it was before the decreasing period Noise at beginning of C2 ZOOM

23. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Effect of the pump Between 13h22 (UTC) and 14h40, all pumps are progressively switched off At 13h59, IB pump switched off ZOOM Between 14h40 and 15h00, original conditions are restored

24. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C3 : scroll pumps OFF (IB), except 5min/day C2 C3 Residual env. noise dominates mainly in [1500, 3000]Hz  Turbo pump (mainly IB) ? IB tower accelerometer Coherence with dark fringe

25. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C2: Mirror internal modes identification l Coloured noise injected at the RM actuators of each mirror l ANSYS mirror simulation l Calibration software (CaRT) l One period at the NA and another at the WE l Mirror internal lines and quality factors measured

26. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C2: North mirror internal modes identification NI: 3917.2 Hz 5584.7 Hz NE: 3883.0 Hz 5542.2 Hz

27. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C2: Mirror Internal modes measurement

28. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C4: Thermal noise Internal modes are now visible in the ITF output (recombined ITF) NE at 5543 Hz WE at 5545 Hz

29. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C3 (North Arm) With SSFS : RFC noise contribution is reduced C3 sensitivity now limited by another kind of noise FFT(Sc_NE_zGc) x Mechanical TF(NE) C2 sensitivity limited by RFC noise

30. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C3 (North Arm) Pr_B1_ACp spectrum (April 23rd, 20:00:00 UTC ) Electronic Noise Shot Noise

31. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C3: Injection Bench lines (10 Hz< f < 100Hz) Input Bench resonances Good coherence around the IB resonances  introduced in the sensitivity by the IMC AA loop Sc_MC_txCorrM Sc_MC_txCorrR Sc_MC_tyCorrM Sc_MC_tyCorrR

32. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C3-Recombined: Electronic Noise Pr_B1_ACp spectrum (April 27th, 12:20:00 UTC ) Electronic Noise (measured with shutter closed) Shot Noise Additional noise

33. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C3-Recombined: West terminal photodiode (B8) noise Hz Gain frequency Transfer function of the standard filter Static gain = 1.727 x 10ˆ9 West arm B8_phase/B8_DC Sc_WE_zCorr Filter Pr_B8_ACp limited by electronic noise above 200 Hz  injected in sensitivity by the control loop Pr_B8_ACp used to acquire the lock of the West Cavity Coherence between B1_ACp & B8 _ACp  sensitivity limited by B8 electronic noise between 200 Hz & 1 kHz

34. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C3-Recombined: West terminal photodiode (B8) noise Standard filter New filter frequency Phase |gain| Roll off @ 300 Hz B8 noise model suits to sensitivity curve between 200 & 1000 Hz New noise structures

35. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C3 Noise limitation to the sensitivity curve 1 - North arm  High frequencies : Electronic noise(?) or noise coming from the ITF (?)  Above 250 Hz : not well understood  Between 10 & 250 Hz : coherence with the correction signals used by the IMC  RFC noise (NA length control loop): does not limit C3 sensitivity, but could limit the sensitivity below 50 Hz for full VIRGO 2 - Recombined configuration  High frequencies : electronic noise  200-1000 Hz : noise due to B8  10-100 Hz : “laser frequency noise” but is reduced at the end of the run

36. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 C4 General results about sensitivity (C4 data still to be discussed)

37. Paolo La Penna ILIAS N5-WP1 meeting Noise analysis in Virgo Cascina, 7-8 July 2004 Summary l Virgo is not in its final configuration: Noise identification means debugging the progress of the activity l The commissiong activity for noise analysis is mainly concentrated on the data from the runs, in identifying the noise sources in the sensitivity curve l Many tools for analysing noise are present, discussion is going on for establishing a common library