patrick.thomas@LIGO.ORG - posted 08:06, Thursday 07 November 2019 - last comment - 09:41, Thursday 07 November 2019(53056)
Ops Owl Shift Summary
TITLE: 11/07 Owl Shift: 08:00-16:00 UTC (00:00-08:00 PST), all times posted in UTC STATE of H1: Observing at 117Mpc INCOMING OPERATOR: Ed SHIFT SUMMARY: Squeezer took us out of observing twice. There is a user message: SQZ_MANAGER: NOT IN MANAGED MODE. LOG: 08:00 UTC Squeezer takes us out of observing 08:02 UTC Hit INIT on SQZ_MANAGER. Squeezer relocked. 08:03 UTC Back to observing 11:01 UTC Squeezer takes us out of observing 11:02 UTC Hit INIT on SQZ_MANAGER. Squeezer relocked. 11:04 UTC Back to observing
Nutsinee, Sheila, Camilla
We looked into the reasons why the squeezer didn't recover automatically last night. We've made 2 changes to the squeezer manager to try to address the problem, but haven't loaded the changes yet.
The problem was that the CLF didn't lock on the first relocking attempt. Currently the guardian only tried to lock it once and then gives up, in the past this always worked on the first try. For now we have added some checks in the SQZ MANAGER LOCK_CLF state to request down from the CLF, wait 5 seconds, and re-request locked.
Another confusing point was that the manager was requesting down from the CLF node while the CLF was trying to relock. Bassically there was a race condition, where the CLF guardian realized that the loop was unlocked, went to down and tried to relock. SQZ_MANAGER has a function called turn_off_sqz() which also requests down from the CLF guardian, which was happening ~ half a second later, once the CLF guardian was already trying to relock. We've edited that function so that it no longer makes requests of the CLF guardian.
The reason the squeezer lost lock was the OPO PZT running out of range, this happened twice overnight.