Below the detail of the new EOM 6MHz amplitude noise injections performed with the ITF locked at LOW_NOISE_3 ( plot )

High-pass filter  4th order  at 40Hz - white noise injection

• 2023-12-15-21h02m21-UTC: white noise level at 1e-5 - high-pass @40Hz - 5mn 
• 2023-12-15-21h07m26-UTC: white noise level at 4e-5 - high-pass @40Hz - 5mn
• 2023-12-15-21h12m28-UTC:  white noise level at 1e-4 - high-pass @40Hz - 5mn
• 2023-12-15-21h17m30-UTC: white noise level at 2e-4 - high-pass @40Hz - 3mn
• 2023-12-15-21h20m31-UTC: white noise level at 4e-4 - high-pass @40Hz - 5mn
• 2023-12-15-21h25m36-UTC:  Disable noise injections - 5mn

This plot at its zoom show  the B2_Audio, B4_Audio and B5_Audio channels and the INJ_EOM 6MHz and 56MHz ampliude channels for this test

• blue rectangle: coherency between the injected noise (INJ_LNFS_6MHz_RAMS_dac) and the Audio channels for B2, B4 and B5 beams
  • same observations as the last measures
• purple rectangle: coherency between  the B2, B4 and B5 Audio channels : idem
• red rectangle: coherency between the EOM 56MHz monitoring channel (INJ_EOM_56MHz_mag ) and the Audio channels for B2, B4 and B5 beams
  • there is coherency in the 10Hz-40Hz frequency band but the coherency remains at the same level independently of  the injected noise level : the contrary of the previous measures

High-pass filter  4th order  at 100Hz - white noise injection

• 2023-12-15-21h30m30-UTC: white noise level at 1e-5 - high-pass @100Hz
• 2023-12-15-21h35m31-UTC: white noise level at 4e-5 - high-pass @100Hz
• 2023-12-15-21h40m31-UTC: white noise level at 1e-4 - high-pass @100Hz
• 2023-12-15-21h45m31-UTC: white noise level at 2e-4 - high-pass @100Hz
• 2023-12-15-21h50m34-UTC: white noise level at 4e-4 - high-pass @100Hz
• 2023-12-15-21h55m35-UTC: white noise level at 8e-4 - high-pass @100Hz
• 2023-12-15-22h00m03-UTC:  Disable noise injections

This plot at its zoom show  the B2_Audio, B4_Audio and B5_Audio channels and the INJ_EOM 6MHz and 56MHz ampliude channels  for this test

• blue and purple rectangles: same observations 
• red rectangle: coherency between the EOM 56MHz monitoring channel (INJ_EOM_56MHz_mag ) and the Audio channels for B2, B4 and B5 beams
  • the INJ_EOM_56MHz_mag ASD values changes  independently of  the injected noise level
  • there is coherency in the 10Hz-40Hz frequency band, but the coherency changes  independently of  the injected noise level too as expected by Matthieu

After some investiagtions we found that the EOM_56MHz_mag channel became noisy since the 2023-12-03 (see this plot ) :

• the origin of this noise increase remains to be investigated
• A flag has been added on the LNFS's DMS