We started the recovery by turning on the BPC of the green beams, and aligning also the signals at the level of the injection. Then it locked without problems.

We then aligned the central interferometer and we tried to lock. The signal of PRCL that uses the 6MHz seemed almost well tuned (initially was 1.6 and it seemed that 1.4 was better, but this had almost no impact). Instead the signal of 56MHz seemed wrong (when engaging the loops, SRCL seemed to diverge). However it is not easy to tune it, since we use I and Q for MICH and SRCL. We have tried to change it until we were able to lock (initially 3.24, we changed until 2.0 and we manage to get short locks). However the lock do not last.

In parallel we noticed that the alignment signals were also mistuned, so we tried to tune them better, however the phase that seemed good for the H didn't seem good for the V (initially 3.2 and seemed ideal one for H was 2.2 - we checked the sign). So I left the phase unchanged and I commented the alignment in the CITF (1829-1830 in DRM1_LOCK.py), to give us some margin to align by hand and see if the lock would last longer. I managed to tune the phases and to close the vertical alignment loop by hand, so I reimplemented it in the automation. I left the horizontal open for the moment.

In the meantime I called Ilaria to check the ChroC since we didn't expect to tune phases (the arms and the RFC didn't need further tuning). She made a small step of the chroc to try to match the previous temperature. I didn't see any change on the demodulation phases. To be checked better tomorrow.