Gabriele Vajente ILIAS WG1 meeting - Frascati Noise Analysis Tools at Virgo

ILIAS WG1 meeting, Frascati – Gabriele Vajente2 Summary Tools for monitoring non-stationary noises Project for an automatic noise budget tool

ILIAS WG1 meeting, Frascati – Gabriele Vajente3 Part 1 Non-Stationary Noise Monitor

ILIAS WG1 meeting, Frascati – Gabriele Vajente4 Non Stationary Noise Monitor Purpose Monitor time evolution of noise level in dark fringe Find correlation with ITF status (alignment, environmental conditions, etc.) Two parts Running online: NonStatMoni Running offline periodically: NonStatMoniOffline Compute band-limited RMS Identify lines Trends Correlation with ITF status

ILIAS WG1 meeting, Frascati – Gabriele Vajente5 NonStatMoni – Band-limited RMS Band-limited RMS Compute short spectra (1, 5, 10 s) every 1 s Output RMS in bands in the main data stream Fully configurable (channel, spectrum length, etc.)

ILIAS WG1 meeting, Frascati – Gabriele Vajente6 NonStatMoni – Lines identification 1 Lines identification Separate lines from “background” Band-limited RMS of background Frequency, height, SNR of main lines (SNR threshold) Running only during “locked” periods Main data stream

ILIAS WG1 meeting, Frascati – Gabriele Vajente7 NonStatMoni – Lines identification 2 In main data stream Number of lines found Background band-limited RMS Frequency, height, SNR for each line found full RMS bkg RMS full RMS bkg RMS 1.11 kHz 3.88 kHz

ILIAS WG1 meeting, Frascati – Gabriele Vajente8 NonStatMoniOffline - Summary Run periodically, analyze all locks of last period Output as web pages Summary of monitored channels Links to locked periods details

ILIAS WG1 meeting, Frascati – Gabriele Vajente9 NonStatMoniOffline – Lock details 1 Run periodically, analyze all locks of last period Output as web pages Plot of RMS time evolution Spectrum of RMS evolution

ILIAS WG1 meeting, Frascati – Gabriele Vajente10 NonStatMoniOffline – Lock details 2 Run periodically, analyze all locks of last period Output as web pages Time plot

ILIAS WG1 meeting, Frascati – Gabriele Vajente11 NonStatMoniOffline – Lock details 3 Run periodically, analyze all locks of last period Output as web pages Spectrum plot

ILIAS WG1 meeting, Frascati – Gabriele Vajente12 NonStatMoniOffline – Lock details 4 Run periodically, analyze all locks of last period Output as web pages Coherence table and plots

ILIAS WG1 meeting, Frascati – Gabriele Vajente13 Examples of applications Enviromental monitoring (seismometers and microphones) Airplanes F. Fidecaro Monitor band- limited RMS for seismic sensors in all buildings. One can recover direction and speed

ILIAS WG1 meeting, Frascati – Gabriele Vajente14 Correlation with alignment and freq noise PR yawBS yaw NE pitch Freq. noise

ILIAS WG1 meeting, Frascati – Gabriele Vajente15 Modes ring-down During lock acquisition mirror and violin modes are strongly excited Extimation of Q factor 3884 Hz  = 106 ± 7 s Q = 1.29 x Hz  = 550 ± 20 s Q = 2.89 x 10 5 Line height [Hz/rHz] RMS between 100 and 200 Hz [Hz/rHz]

ILIAS WG1 meeting, Frascati – Gabriele Vajente16 Part 2 Automatic Noise Budget Project

ILIAS WG1 meeting, Frascati – Gabriele Vajente17 Automatic Noise Budget Purpose To measure precise projection of technical noises into dark fringe (or other channels) Why To precisely identify the contribution of the most important noise sources To track the evolution of noise couplings To gain data to model noise couplings

ILIAS WG1 meeting, Frascati – Gabriele Vajente18 Method 1.Measure transfer function from error/correction signal to dark fringe with noise injection 2.Project the normal noise using the measured TF Interferometer Control loop Dark fringe NOISE SINGLE CAVITY

ILIAS WG1 meeting, Frascati – Gabriele Vajente19 TF measurement methods Full measurement By injecting (white) noise into each channel separately Slow (at least 60s per channel) Precise measurements of TFs Might cause saturation problems or unlocks Need to “shape” the noise Fast measurement Measure once the TFs with full method Use calibration lines to correct their overall gain Fast (can inject lots of lines simultaneously) Might be not very precise Can easily track time evolution Lines measurement Inject several (10) lines for each d.o.f. at different frequencies Need to know the approximate shape of the TF Faster than full, more accurate than fast Less saturation problems

ILIAS WG1 meeting, Frascati – Gabriele Vajente20 Technical noise sources Control noises Longitudinal (DARM, MICH, PRCL) 3 dof Angular (PR, BS, NI, NE, WI, WE tx & ty) 12 dof Input beam noises Frequency noise 1 dof Laser power noise 1 dof Input beam jitter (translation & tilt) 4 dof IMC controls (angular and longitudinal) 3 dof Modelled noises Shot noise (need only power measurements) Dark noise DAC noise Phase noise

ILIAS WG1 meeting, Frascati – Gabriele Vajente21 Outcomes of the tool Noise budgets Transfer functions Using permanent calibration lines Track time evolution of noise couplings and ITF performances Better identify non-stationarity sources

ILIAS WG1 meeting, Frascati – Gabriele Vajente22 Conclusions Non-stationary Monitor Developed and tested, already running online Monitor dark fringe and 25 environmental channels Automatic generate summary web pages Automatic Noise Budget Clear project Already tested some noise injection in single cavity configuration