The shift was mostly dedicated to the preparation of accelerometers and bluetooth shaker setup for investigating possible noise coupling at the SDB1-SDB2 window.
Meanwhile, Alexis and Christos repositioned and cabled the big coil in the CEB upper terrace and connected the big amplifier to DAQroom DAC. Also, they performed magnetic injections in the Far Field to measure the coupling to the SDB1 electronics and SDB1 tower S flange using the magnetic probes we positioned there during Wednesday shift.
This magnetic injection log is in: /virgoData/NoiseInjections/MagneticInjections/Magnetic-1256034138.txt, and a copy is here.
Here a picture of the accelerometers and shaker setup at SDB1 and SDB2 minilinks, and here is a scheme with accelerometer names.
We did some quick explorative injections of white noise (also because it is the first time we use this little bluetooth shaker that our KAGRA colleagues suggested us!). Details and GPS are reported in the attached log file:
- shaker on B1 pipe: Figure 1 and Figure 2 (zoom)
- shaker on B1s pipe: Figure 3
- shaker on SDB2 flange: Figure 4
- shaker on SDB1 tower base: Figure 5
The volume of the shaker was set at about half of permitted range.
Preliminary we observe that: we managed to excite significantly vibration of the pipes and some resonances (around 68Hz, 288Hz, 143Hz) but in a very localized way, and essentially nothing is transmitted to the big SDB1 tank, as demonstrated by accelerometers ENV_DT_ACC_Z (big flange) and ENV_SQZ_PIPE_Y (extension pipe facing SQZ bench). Also, these injections see to produce no visible effect.
The shaker also produce a not negligible sound. Yet, the fact that when we deployed it on SDB1 tower base saw essentially no vibration of the the link pipes convinces us that the sound->vibration coupling is negligible.
The work has to be continued in Sunday shift.
