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Environmental Monitoring (Environmental Monitoring)
nauwelaers, lalleman, fiori - 18:04 Saturday 09 September 2023 (61566) Print this report
Acoustic injection in NEB and WEB

We performed acoustic injections using a subwoofer. The subwoofer was placed in two different locations in both the NEB and WEB. Amplitude was gradually increased.


Chronological description of the events:
Firstly, the subwoofer was placed near the door in the WEB, connected to the amplifier and the DAC.
Interferometer was locked, calibration lines turned off.

09 Sep 2023 07:51:33 UTC (09 Sep 2023 09:51:33 CEST)
Quiet reference started.

1378281638 09 Sep 2023 08:00:20 UTC (09 Sep 2023 10:00:20 CEST)
Stopped the reference.

1378281949 09 Sep 2023 08:05:31 UTC (09 Sep 2023 10:05:31 CEST)
Injected coloured noise with bandpass filter -3db outside 10Hz and 1190Hz in the WEB with amplitude 10^-5 V.

1378282192 09 Sep 2023 08:09:34 UTC (09 Sep 2023 10:09:34 CEST)
Increased amplitude of injection to 10^-4V.

1378282341 09 Sep 2023 08:12:03 UTC (09 Sep 2023 10:12:03 CEST)
Increased amplitude of injection to 10^-3V.

1378283193 09 Sep 2023 08:26:15 UTC (09 Sep 2023 10:26:15 CEST)
Increased amplitude of injection to 5*10^-3V.
Limited oscillations visible on Sa_WE_F0_TY.

1378283995 09 Sep 2023 08:39:37 UTC (09 Sep 2023 10:39:37 CEST)
Stopped injection.

1378284202 09 Sep 2023 08:43:04 UTC (09 Sep 2023 10:43:04 CEST)
Changed injection to coloured noise with bandpass filter -3db outside 10Hz and 110Hz in the WEB with amplitude 5*10^-3V.

1378284396 09 Sep 2023 08:46:15 UTC (09 Sep 2023 10:46:15 CEST)
Airplane flew close to the main building.

1378284608 09 Sep 2023 08:49:50 UTC (09 Sep 2023 10:49:50 CEST)
Increased amplitude of injection to 2*10^-2V.
Coherence visible on ENV_WEB_MIC vs Hrec_hoft_20000Hz between 10Hz and 10^2Hz.

1378285170 09 Sep 2023 08:59:12 UTC (09 Sep 2023 10:59:12 CEST)
Increased amplitude of injection to 5*10^-2V.
Increased high-frequency noise and low-frequency oscillations visible on super attenuator (Sa_WE_F0_TY).
Broadband noise in interferometer visible.

1378285389 09 Sep 2023 09:02:49 UTC (09 Sep 2023 11:02:49 CEST)
Stopped injection.
Noise on super attenuator immediately disappeared.
All noise effects were reversible.

1378288069 09 Sep 2023 09:47:31 UTC (09 Sep 2023 11:47:31 CEST)
Went to WEB, changed the position of the subwoofer within WEB so it was far away from the door.
Injected coloured noise with bandpass filter -3db outside 10Hz and 1190Hz in the WEB with amplitude 5*10^-3 V.

1378289132 09 Sep 2023 10:05:14 UTC (09 Sep 2023 12:05:14 CEST)
Stopped injection.

1378289207 09 Sep 2023 10:06:29 UTC (09 Sep 2023 12:06:29 CEST)
Increased amplitude of injection to 1*10^-2 V.
Started injection.

1378289405 09 Sep 2023 10:09:47 UTC (09 Sep 2023 12:09:47 CEST)
Stopped injection.

1378292049 09 Sep 2023 10:53:51 UTC (09 Sep 2023 12:53:51 CEST)
Brought the amplifier from WEB to NEB.
Interferometer became unlocked (probably by visitors in the main building).
Two short injections with low amplitude to test the 'ramp-up' of the subwoofer.

1378292291 09 Sep 2023 10:57:53 UTC (09 Sep 2023 12:57:53 CEST)
Stopped test injections.

1378307130 09 Sep 2023 15:05:12 UTC (09 Sep 2023 17:05:12 CEST)
Went to NEB, changed the position of the subwoofer within NEB so it was far away from the door. Placed on the side of the rack (other side than on the WEB).
Picture of new subwoofer position taken by Olivier.
Injected coloured noise with bandpass filter -3db outside 10Hz and 1190Hz in the WEB with amplitude 5*10^-3 V.

1378307432 09 Sep 2023 15:10:14 UTC (09 Sep 2023 17:10:14 CEST)
Stopped injection.

1378307514 09 Sep 2023 15:11:36 UTC (09 Sep 2023 17:11:36 CEST)
Increased amplitude of injection to 1*10^-2 V.
Started injection.

1378307827 09 Sep 2023 15:16:49 UTC (09 Sep 2023 17:16:49 CEST)
Stopped injection.
No significant excess of hrec and no coherence measured.

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Comments to this report:
nauwelaers, lalleman, fiori - 21:53 Wednesday 13 September 2023 (61628) Print this report

The following information was omitted from the log entry. Between 12:57:53 UTC (stopped test injection) and 14:53:00 (changed position of the subwoofer), the following events occured:

 


1378303816  09 Sep 2023 14:09:58 UTC  (09 Sep 2023 16:09:58 CEST)
Interferometer was locked again, reference lines disapeared.
Injected coloured noise with bandpass filter -3db outside 10Hz and 1190Hz in the NEB with amplitude 10^-3 V. During these injections, the subwoofer was placed close to the door.

1378304153  09 Sep 2023 14:15:35 UTC  (09 Sep 2023 16:15:35 CEST)
Stopped injection.

1378304163  09 Sep 2023 14:15:45 UTC  (09 Sep 2023 16:15:45 CEST)
Started taking new reference function for NEB injection.

1378304439  09 Sep 2023 14:20:21 UTC  (09 Sep 2023 16:20:21 CEST)
Stopped taking new reference.

1378304458 09 Sep 2023 14:20:40 UTC  (09 Sep 2023 16:20:40 CEST)
Increased amplitude of injection to 5*10^-3V.
Increased high-frequency noise and low-frequency oscillations visible on super attenuator (Sa_NE_F0_TY).


1378304848  09 Sep 2023 14:27:10 UTC  (09 Sep 2023 16:27:10 CEST)
Stopped injection.


1378304950  09 Sep 2023 14:28:52 UTC  (09 Sep 2023 16:28:52 CEST)
Changed injection to coloured noise with bandpass filter -3db outside 10Hz and 110Hz in the NEB with amplitude 2*10^-2V.
Mainly high-frequency noise increased on super attenuator (Sa_NE_F0_TY).


1378305348  09 Sep 2023 14:35:30 UTC  (09 Sep 2023 16:35:30 CEST)
Stopped injection.

1378305428  09 Sep 2023 14:36:50 UTC  (09 Sep 2023 16:36:50 CEST)
Increased amplitude of injection to 5*10^-2V.
Around 20-30Hz there is coherence between ENV_NEB_MIC_FFT and Hrec_hoft_20000Hz_FFT.

1378305754  09 Sep 2023 14:42:16 UTC  (09 Sep 2023 16:42:16 CEST)
Stopped injection.

 

fiori, tringali, lalleman, nauwelaers - 14:06 Thursday 14 September 2023 (61639) Print this report

We attach again the log file of measurements since some gps times were missing.

Some comments about what we observed during injections.

  • We injected a quite loud acoustic noise which overcome the quiet condition up to a factor 100 at 100Hz and a factor of a few also at 10Hz. This induced a substantial vibration of the building floor, vacuum chamber, and filter zero of the suspension. This is shown in Figure 1 for the WEB and Figure 4 for the NEB.
  • Note: our objective was to inject the loudest sound in order to either detect something in hrec or set the highest possible upper limit on ambient noise.

Impact on Hrec:

  • when injecting at WEB the loudest colored sound at 10-1190Hz we observed an increase (by about a factor 3) of the Hrec noise in the range 10 to 30 Hz with a triplet of lines at 9.7, 14.1 and 19.4 Hz (Figure 1, purple curve). We do not know if they can suggest about a possible noise path. We also observed some arches in the SWEB_B8_DC photodiode (Figure 2), although it is not clear that they are indeed the cause of the hrec noise since there is no coherence between the two signals (Figure 3, blue curve). When injecting at even louder level between 10 and 110Hz we observed the appeareance of a broadband noise in Hrec from 20 to 200Hz (Figure 1, blue) with a slope of approximately 1 / f^2. Correspondently the F0_TY of the WE superattenuator was very excited also at low frequency. In addition the onset of this noise occurred with some substantial delay (about 20s) with respect to the start of our injection and ended as well 20s after we stopped the injection (Figure 2). It is possible that we disturbed some ITF global control.
  • the same colored sound noises injected at NEB produced a smaller effect. The loudest colored noise in the 10-1190 Hz range did not produce any visible effect in Hrec (Figure 4, purple). The even louder colored noise in the 10-110Hz caused instead some noise increase in the region mainly between 10 and 20 Hz (smaller than for WEB)  but also an increase of the sideband noise around several lines (Figure 4, blue).
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Fiori, Paoletti, Tringali - 13:28 Thursday 31 October 2024 (65438) Print this report

We performed acoustic injections in both terminal buildings. Details are in the attached log file.

The purpose is double: 1) check if the coupling has changed after more that one year; 2) produce better coupling function for the IME deliverable "acoustic rooms for racks".

We injected different kind of noise:

  • colored noise 8Hz to 2kHz
  • colored noise 10-110Hz
  • colored noise 200-300Hz (main emission frequency range of racks)
  • line at 220 Hz (one of the main emission frequency of racks) and 240 Hz (NEB only)

At WEB we notice a significant coupling in the region 100-300Hz. Figure 1 and 2. The excited structures in hrec are similar to those excited during the tapping campaign, and are likely realeted to the scattered light issue.

Similar injections at NEB did not produce noticeable effects in hrec (Figure 3)

 

 

 

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