Some results of our tests are reported hereafter.

Noise assesment of the Big turbo pump:

1. The IB turbo pump produces broadband seismic noise (from 100 Hz to kHz) in addition to a narrow line and few harmonics associated to the rotor speed. The broadband noise is associated to the active magnetic levitation system, as we deduce from the fact that it onsets as soon as the magnetic levitation system activates while the rotor frequency rises (Figure 1 and Figure 2).
2. This vibration noise is sensed in accelerometers attached to the IB VAC chamber and very little at the level of the CryoTrap (Figure 3).
3. Some noise is sensed also inside Laser Lab, by the BPC sensors and the microphone (Figure 4 and Figure 5).
4. Some coherence is detected between sensors in the LaserLab (BPC and microphone) and the accelerometer placed on the turbo pump (Figure 6)
5. Some Magnetic noise is produced and sensed by the magnetometer placed onto the pump, but nothing is sensed by magnetometers placed at the IB W and S flanges (again Figure 1 and  Figure 2)
6. It has to be noticed however that magnetic noise around IB tower is high relative to what is measured around the NI tower (Metronix magnetometers are now located there) (Figure 7) THIS HAS TO BE INVESTIGATED FURTHER.
7. No big difference is noticed in the produced noise (seismic and magnetic) when the same pump is run at 600 Hz (max speed). The broadband vibration noise spectrum is the same, just lines moved from 400Hz to 600Hz, with roughly the same amplitude (Figure 8 and Figure 9)

Noise assessment of the Small turbo pump:

1. This pump produces vibration noise at the rotor speed (546 Hz) but the broadband vibration noise associated with the levitation system is much smaller, and only measureable by the sensor right on the pump (Figure 10 and Figure 11).
2. The amplitude of seismic lines at rotation speed is similar to that of the big turbo within a factor 2. (Figure 11)
3. When the pump is run at maximum speed (820 Hz) the seismic line moves correspondently, and its amplitude is roughly the same (Figure 12)
4. Some broadband magnetic noise is sensed by the magnetometer nearby to the pump, but nothing is sensed by magnetometers placed at the IB W and S flanges (same comment of point 6 above applies) (Figure 13 and Figure 14).

Today, measuring the magnetic field around the CEB towers, we noticed that the ENV_IB_MC_PIPE_MAG_X magnetic sensor was not on the MC pipe as the name states, but instead on the IB tower's large flange ("flangiona"), PR side.

On the contrary, the ENV_IB_MAG_Z  was on the IB tower's large flange, MC side.

We therefore decided to swap the cables at the ADCs level, at 08:00 UTC - now ENV_IB_MC_PIPE_MAG_Xis on the MC side, while ENV_IB_MAG_Z is on PR side (see attached plot showing the time of the action)

BTW this latter sensor was found 45 degrees rotated relative to the Virgo axis: we put it back in its original orientation, but we think it will need a more robust fixing.