1. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 1 M.Varvella Virgo LAL Orsay / LIGO CalTech Time-domain model for AdvLIGO Interferometer Gravitational Wave Detectors Workshop Roma, October 21, 2004

2. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 2 Outline LAL activities for upgraded Virgo: – the signal recycling option collaboration with LIGO Caltech: – 40m/AdvLIGO simulation – dual recycled 40m commissioning e2e simulation: –Mach-Zehnder –40m/AdvLIGO –from 40m/advLIGO to upgraded Virgo

3. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 3 Power Recycling Mirror Signal Recycling Mirror Cavities LASER Sensitivity Without Signal Recycling With Signal Recycling SIGNAL RECYCLING 5 longitudinal d.o.f. to be controlled Locking and Alignment problems Control strategies better sensitivity in a narrow frequency band

4. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 4 Frequency (Hz) Sensitivity (/Hz 1/2 ) Virgo AdvVirgo with SR AdvVirgo Arm finesse = 600 f sr = 800 Hz r sr = 0.9 SIGNAL RECYCLING for Virgo Example of SR sensitivity curve

5. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 5 Collaboration Virgo LAL - LIGO CalTech 40m IFO group LIGO simulation group 40m commissioning PSL ETMy ETMx ITMy ITMx BS PRM SRM MC e2e simulation for 40m/advLIGO re-summation cavity formulation

6. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 6 SIGNAL EXTRACTION for 40m/AdvLIGO Arm cavity signals are extracted from beat between carrier and f 1 or f 2. Central part (Michelson, PR, SR) signals are extracted from beat between f 1 and f 2, not including arm cavity information. f1f1 -f 1 f2f2 -f 2 Carrier (Resonant on arms) Single demodulation Arm information Double demodulation Central part information ETMx Two modulations are used to separate high finesse, 4km long arm cavity signals from Central part (Michelson, PR, SR) signals. ETMy ITMy ITMx BS PRM SRM 4km f 1 = 33 MHz f 2 = 166 MHz f 1 = 9 MHz f 2 = 180 MHz 40madvLIGO

7. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 7 SIDEBANDS of SIDEBANDS Desire to control short degrees of freedom (MICH, PRC, SRC) using beats between RF sidebands only (f 1 ±f 2 ), no carrier, to be immune to large signals from arm cavities Application of f 1 and f 2 using serial EOMs produces sidebands on sidebands, at (f 1 ±f 2 ), so that beats appear with carrier, corrupting signals for short dof’s. After considering several solutions, EOMs in parallel via Mach-Zehnder interferometer have been installed. Simulation Real world EOM2 EOM1 EOM = Electro-Optical-Modulator

8. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 8 Control –Originally, using internal modulation with 33 MHz (f 1 ) to lock MZ –Might need to turn down 33, 166 (f 2 ) MHz during lock acquisition procedure; don’t want to lose MZ lock –Instead, put 29 MHz EOM (used for MC lock) into MZ east arm, and lock with that  now using 29MHz MACH-ZEHNDER on 40m PSL EOMs in seriesEOMs in parallel (Mach-Zehnder)

9. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 9 SIMULATION First approach → e2e simulation –LIGO e2e simulations understanding –40m/advLIGO model in progress The same model for both the interferometers (same configurations); all the parameters are specified in macros to simplify the switch between configurations. Long term goal: –Signal Recycling package for upgraded Virgo Adaptation of the 40m/advLIGO model to Upgraded Virgo

10. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 10 e2e SIMULATION: Mach-Zehnder EOM2 EOM3EOM1 PD EOM2 EOM1 PZT PMC trans To MC EOM3 EOM 1 → 33 MHz EOM 2 → 166 MHz EOM 3 → 29 MHz

11. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 11 Simulation time 0.25 s Error signal Control signal Mirror displacement Seismic Noise LOCK ACQUISITION of the MACH-ZEHNDER 0-0.05s open loop 0.05-0.1s gain=0.02 0.1-0.15s gain=1 0.15-0.2s gain=10 0.2-0.25s gain=100 MZ Lock acquired

12. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 12 Boost: 1 Pole @ 100 Hz, 1 zero @ 1 kHz 1 Pole @ 220 Hz 3 Poles @ 300 kHz Dc Gain 80 dB Mach-Zehnder Feedback Filter TF (real and simulated)

13. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 13 Mach-Zehnder Open Loop TF (real and simulated)

14. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 14 e2e SIMULATION: 4Om/AdvLIGO optical configuration IFO Central partIFO with Arms

15. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 15 EOMs in series SBs on SBs Mach-Zehnder No SBs on SBs e2e SIMULATION: 4Om/AdvLIGO package optics signals monitoring mirror positions laser

16. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 16 Mirrors positionsSignals Monitoring e2e SIMULATION: 4Om/AdvLIGO package

17. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 17 EQUILIBRIUM FIELDS VALUES COMPARISON between TWIDDLE and e2e RESULTS EOMs in series Twiddlee2eTwiddlee2eTwiddlee2eTwiddlee2eTwiddlee2e -f 2 %-f 1 %carrier %f1f1 f1f1 %f2f2 f2f2 % Input0.0025 0.00.0025 0.00.9900 0.00.0025 0.00.0025 0.0 SP0.0025 0.00.0021 0.0 0.0020 0.00.00000.00010.0 AP0.0000 0.00.0002 0.00.0000 0.00.0002 0.00.0023 0.0 PRC0.0001 0.00.09380.09350.316.486 0.00.11580.1151-0.60.03290.0328-0.3 SRC0.0001 0.00.0028 0.00.0000 0.00.0030 0.00.03060.0304-0.6 Arm X0.0000 0.00.0000 0.06378.76378.6-0.00.00000.0000.00.0000 0.0 Arm Y0.0000 0.00.0001 0.06378.76378.6-0.00.00000.0000.00.0001 0.0 [ value (e2e) – value (Twiddle)] value (Twiddle) % = Good agreement between the two simulations TWIDDLE is a frequency domain simulation code using the Mathematica framework

18. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 18  Mach-Zehnder: Transfer functions and displacement noise simulation of the Mach-Zehnder package Comparison with 40m raw data  good agreement between simulation and raw data but improvements are necessary to match them better  40m/advLIGO:  Calculation of the equilibrium fields values configuration with EOMs in series  to compare with Twiddle results and validate optics good agreement configuration with Mach-Zehnder  just to evaluate the equilibrium fields values with different choices of modulation depth e2e SIMULATION: Summary

19. Monica VarvellaIEEE - GW Workshop Roma, October 21, 2004 19 PLANNING e2e validation of the phase noise introduced by the mirror displacements  already calculated by S.Kawamura with Finesse Length Sensing matrix implementation To be added: suspensions, electronics, mode cleaner … more Improvement of the simulation speed: re-summation cavity formulation → technique used to avoid full propagation in the ITF central part Application of all acquired knowledges to Upgraded Virgo Short term ( next months ): Long term ( next year ):