The first part of today's shift was devoted to send the error signals from B2 to the SSFS DSP so that we can use both error signals for this loop. Unfortunately it turned out that the communication between the PD and the SSFS is not working.
After that we experienced a problem with the suspended injection bench, an oscillation around 1Hz appeared, that was causing the saturation of one of the actuators and would make the bench to oscillate. We opened and closed again the controls and the problem was solved. To do so Eric needed to unlock the PMC manually, from the laser lab. Later on we realized that the trigger possibly was due to the activity on SIB2 trying to investigate the lack of communication. We should remember that now that the EIB is suspended we can not walk next to it!!
Then the ITF relocked in Low Noise 1 kind of straightforward. We adjusted a bit the PR loop in order ot maxiize the sidebands recycling gain.
Then we faced another problem, DARM correction was saturating. In principle we thought that it was the fault of the 150 Hz, and we tried to make a deeper notch. However, we realzed that the frequency of this peak would change with time. The change in frequency changes from lock to lock, sometimes there is no saturation at all, sometimes the line would move very fast from 140-160 and we could also see appear a line at 174 Hz or even at 96 Hz. We do not understand its origin, but as it moves it is impossible to notch it and it causes the ITF to unlock. It would even seem that the line would move as I move the notch...
We have also tried to lock the OMC two times without success...