Environmental Monitoring of Virgo

1. Environmental Monitoring of Virgo Irene Fiori European Gravitational Observatory 21 March 2019 VIR-0285A-19

2. Outline Motivation Sensors ENV studies (examples) Challenges towards next generation of GW detectors

3. Environmental influences on GW interferometer Electro Magnetic fields Radio waves (6MHz, 8MHz, 56MHz) Act on mirror MAGNETS RF modulated laser beam used for angular and longitudinal controls Seism & Sounds Slow ground motion excite vibrations of vacuum pipes and tanks, optics on in-air benches Excite mechanical modes of mirrors and optical benches suspensions Imprint phase noise on spurious scattered light beams Extremely sensitive detector (GW150914 BH-BH signal produced ΔL / L ≈ 10-22) Many external disturbances can couple

4. Virgo noise curve

5. Anthropic and geophysical noise sources 5

6. Electronic devices, cooling fans Self-inflicted noise Chillers Vacuum pumps Electrical system, cables Illumination, Uninterruptible Power Supply Air ventilation

7. Environmental sensors • Monitoring of environmental influences to the detector • Network of probes in experimental halls: Central, NorthEnd, WestEnd, ModeCleaner • 130 fast sensors (sampling 1kHz to 20kHz) • 300 slow sensors (sampling 1Hz) • 1000 monitors of infrastructure devices operation • Signals are acquired synchronously and stored together with all the rest of interferometer signals and used for noise investigations Lightning sensor Weather station

8. Noise hunting! … often it requires further measurements and tests, and sniffing around Mitigation actions Track and locate sources Correlate noise in ENV probes and ITF Many analysis tools, online or on-demand ( DetChar) Silence the source Reduce coupling to ITF VETO data segments (until problem fixed)

9. Measure ITF coupling to ambient noise Hrec Coil for magnetic injections Microphone Loudspeakers Projected contribution We add ambient noise in controlled way Sound, Vibrations, Magnetic, RF This “transfer function” is used project the “quiet condition” ambient noise (Noise Budget) Identify critical coupling PATHS  mitigation

10. Noise Cooling fans • Periodic noise (frequency lines) • Transient noise (glitches)  frequency Helicopter Helicopter Traffic noise 1-5Hz RMS  time Water chiller on/off cycle

11. Towards more sensitive detectors AdV (65-85 Mpc) 2019 (O3) AdV+ (85-125 Mpc) 2022-2023 (O4) Einstein Telescope ~2030, x10 and bandwidth extended to 1 Hz (underground, cryogenic)

12. Newtonian Noise (NN) !! NN cannot be shielded !! • Fluctuations of gravity field at the test mass • soil density fluctuations • air density fluctuations

13. Newtonian Noise – projections • NN is close to limit between 10 and 30Hz • Main contribution is from Infrastructure noise (air conditioning …) • seismic NN • Main contribution: Rayleigh waves in Building floor (from air conditioners & vacuum pumps) • infrasound NN • Main contribution: sound inside experimental buildings (infrastructure)

14. POLGRAW group, GSSI APC Paris, EGO Newtonian noise, subtraction • !! Mitigation of noise from infrastructure (air conditioning) seismic and acoustic noise inside experimental halls !! Study of seismic and sound response of the experimental buildings Dense array of seismometers deployed inside Virgo Terminal buildings Network of seismometers (microphones) can reconstruct density fluctuations and displacement force at the mirror  compensate by applying an opposite force on the mirror Studies ongoing

15. Challenges towards AdV+ • Low Noise Infrastructure: (mandatory for NN) mitigate seismic and acoustic noise from ITF infrastructure devices (mainly air conditioning) • Keep under control anthropic noise: • Airplanes, helicopters: no-fly-zone agreed with military authorities (Feb. 2019) • Wind farms, and other noisy installations: agreed with local authorities about Upper Limits of noise emissions from new installations in the area (agreement signed 2011) • So far it saved us from: more wind parks, one motor speedway, few earth quarries • Global Earth noise can affect the World Network of Interferometers and mimic GW candidates or stochastic GW background noise (Schumann fields, gigantic lightings, geomagnetic pulsations, solar activity, large cosmic ray showers) • Improve the site monitoring: external magnetic station, cosmic ray detector • Collaboration agreement with Radio-frequency and EM sensors networks • Earthquake Early Warning alert (with INGV)

16. Case study 6km VIRGO 1.7 Hz Wind turbines vibration noise (with INGV) Soil vibration at 1.7Hz detected at 6km distance Propagation model Gilberto Saccorotti et al, https://doi.org/10.1785/0120100203

17. Challenges towards AdV+ • Low Noise Infrastructure: (mandatory for NN) mitigate seismic and acoustic noise from ITF infrastructure devices (mainly air conditioning) • Keep under control anthropic noise: • Airplanes, helicopters: no-fly-zone agreed with military authorities (Feb. 2019) • Wind farms, and other noisy installations: agreed with local authorities about Upper Limits of noise emissions from new installations in the area (agreement signed 2011) • So far it saved us from: more wind parks, one motor speedway, few earth quarries • Global Earth noise can affect the World Network of Interferometers and mimic GW candidates or stochastic GW background noise (Schumann fields, gigantic lightings, geomagnetic pulsations, solar activity, large cosmic ray showers) • Improve the site monitoring: external magnetic station, cosmic ray detector • Collaboration agreement with Radio-frequency and EM sensors networks • Earthquake Early Warning alert (with INGV)

18. Geomagnetic pulses Gigantic-jet of December 12 2009, near Corsica Detected by magnetometers at LIGO and Virgo and by the Virgo detector I.Kowalska, et al., https://arxiv.org/abs/1612.01102 irene fiori - astrop and geoscience, paris • Very energetic electric discharges in atmosphere can produce “coincident” (light-speed separated) noise transients in word-wide detectors • This can FAKE a real GW signal!! • Solution? (not easy) Measure it and VETO.

19. Challenges towards AdV+ • Low Noise Infrastructure: (mandatory for NN) mitigate seismic and acoustic noise from ITF infrastructure devices (mainly air conditioning) • Keep under control anthropic noise: • Airplanes, helicopters: no-fly-zone agreed with military authorities (Feb. 2019) • Wind farms, and other noisy installations: agreed with local authorities about Upper Limits of noise emissions from new installations in the area (agreement signed 2011) • So far it saved us from: more wind parks, one motor speedway, few earth quarries • Global Earth noise can affect the World Network of Interferometers and mimic GW candidates or stochastic GW background noise (Schumann fields, gigantic lightings, geomagnetic pulsations, solar activity, large cosmic ray showers) • Improve the site monitoring: external magnetic station, cosmic ray detector • Collaboration agreement with Radio-frequency and EM sensors networks • Earthquake Early Warning alert (with INGV)

20. Earthquakes UNLOCK! 3km arm cavity, stored power • Low Latency Earthquake Early Warning- knowing at least few seconds in advance about the arrival of EQ would permits to put the interferometer in a “more robust” and safe state and keep it operational P S • EEWS design study, ongoing project of INGV-Pisa and EGO-Virgo • Marco Olivieri et al. POSTER session irenefiori - astrop and geoscience, paris • Low frequency ground motion causes Superattenuator’s control to fail and interferometer to “unlock”. It can take long time to damp the excited SA modes and recover. • Mostly sensitive to shear S-wave and Surface waves (lower frequency content) Oct 13 2018 11:10 M6.2, 451km, 8844km, Kuril islands

21. Thank you for your attention