Today we worked on the pre-alignment of the CITF and the test with the lock of the ALS:

• we started by relocking the arm cavities, in order to relign the optics and the input beam; we could see that the spikes on B7 and B8 were present again (see #50856 and #50910); we spent some time looking into this without finding any conclusive cause, but we could notice some secondary flashing appearing on the B1p camera;
• while looking into that we re-enabled the B5 drift control on SDB1, with no apparent change; we checked the position of the SNEB/SWEB benches (see #50913 for more details); while the power on B8 improved in its steady value, no changes were observed concerning the spikes; given that the new setpoints degraded a lot the alignment of the green beams, which we wanted to use later on in the shift, we decided to restore the old positions; the re-alignment will be done on Monday profiting on the presence of both crews;
• then we tested the logic for the new protection for SDB1 (see #50911); the logic is working fine and now we decided the correct implementation which will be used by the Automation; the code is being written offline so, in addition to what Paolo wrote in the aforementioned entry, PLEASE DO NOT USE METATRON TO STEER PR AND SR; the new version of the code should be deployed on Monday;
• then we used the new procedure for the CITF alignment, checking that everything was fine on SDB1/2 and that the safety between PR and SR was working (Figure 1):
  • we misaligned NE, WE and WI;
  • we realigned PR, adjusting its position finely looking at fringes and the B1p camera; SR was correctly parked so the new safety allowed this;
  • we misaligned PR, then we realigned SR; with PR parked, there is no issue about SDB*; we proceeded with the fine alignment for SR;
  • keeping SR aligned, we realigned PR and WI, so we got to have the CITF aligned;
  • free swinging data has been acquired starting from 18:45:00 UTC, duration 15 minutes; these data will be analyzed offline;
• we started to write some test triggers in LSC_Acl for the CITF; however, while the new channels themselves did not cause errors, putting them in the DAQ did, throwing an error about the Tolm Packet, but pointing to a completely unrelated channel (see the log attachment); we will contact experts and figure this out (and add a couple of channels to LSC_Acl); in any case the trigger signals can be reconstructed offline for this first analysis;
• then we went back to standard conditions, and relocked the arms on the IR: optics realigned, same power levels as before, spikes still there;
• we locked the ALS on both arms, reallocating the correction on the mirrors, in the single arm basis; this was smooth and without issues; then we realigned the recycling mirrors (see Figure 2), first SR (at 19:09 UTC) then PR (at 19:11 UTC); the green lock was undisturbed and everything looked fine on SDB2: the DC levels of B1p and B5 were only slightly higher with respect to the pure CITF configuration we had before;
• after this we misaligned the recycling mirrors and relocked the arms on the IR beam, we found out that the spikes were gone from both B7 and B8; since the very next step involved less use of online data, we kept the arms locked trying to address also the spikes issue; more details will be posted in the proper thread.