At the begining of the shift we took some time to adjust the phase of the vertical LVDT on SPRB.
One LVDT (FL_V) was especially wrongly tuned with most of the signal in quadrature, we tuned the phase of the LVDT to recover the information in the in phase signal. We realised that the error signal of this LVDT had the wrong sign, so we changed the sign of the calibration factor.
Finally we fined tuned all vertical LVDT changing the phase as follows :
- FL_V : 0.78 ==> 2.18
- FR_V : 0.44 ==> 0.34
- BL_V : 1.375 ==> 1.42
- BR_V : -2.30 ==> -2.09
Fig 1 shows the FFT of the *_V_out_i and *_V_out_q signals for the vertical LVDT, one can see that all the signal is in-phase.
Fig 2 shows the time series of the *_V_out_i, *_V_out_q as well as the *_V_err signals, one can see that the quadrature signals are mostly noise.
Then we recovered the position of the bench to have the beam impinging on the photodiodes (longitudinal and quadrant ones) and being centered on SPRB_B4_Cam1.
The new setpoints of the bench are the following :
- TX_set = 250 urad (previously 76 urad)
- TZ_set = -40 urad (previously -180 urad)
- TY_set = -600 urad (previously -610 urad)
- Y_set = -120 um (previously 100 um)
There is still a bit of coupling between the vertical d.o.f (TX, TZ and Y) because of the calibration factor of the LVDT. More time is needed to fix this small issue (that is not preventing locking and commissioning).
Then the ITF has been locked briefly to LN3.
Also we did not touch any of the horizontal LVDT.
