aLIGO LHO Logbook

H1 AOS

louis.dartez@LIGO.ORG - posted 00:38, Tuesday 12 March 2024 - last comment - 10:39, Tuesday 12 March 2024(76282)

Testing New DARM configuration

E. Hall, S. Pandey, S. Dwyer, L. Dartez

We took another look at the new DARM configuration this evening. Evan had a suggestion for a new test: move into NLN_ETMY, pause here before switching back to ETMX in the new configuration (but after all the new filters have been put into place) to take measurements of the new ETMX OLG before activating it. I took us into NLN_ETMY using the guardian then manually ran the instructions in NEW_DARM to set up the ETMX locking filters but paused before switching arms (so we were still locked with ETMY, notably without the MICH feedforward which remained inactive for the rest of our testing).

We measured H1:SUS-ETMX_L3_LOCK_L_IN1 / H1:SUS-ETMX_L3_LOCK_L_IN2 and H1:SUS-ETMY_L3_LOCK_L_IN1 / H1:SUS-ETMY_L3_LOCK_L_IN2 (DTT template paths are below) to isolate the OLG for the new DARM path on the x-arm. Some post-processing of the data is needed to do this. We'll follow up with that.


Finishing the Transition to the new state:
After the measurements above (but before we had a chance to look at the data) we tried slowly bringing up ETMX slowly starting with an L3 LOCK gain of 0.01 (and an ETMY L3 LOCK gain of 1). We immediately lost lock. This indicates that there is something severely wrong with the new DARM configuration as it's currently installed. Most likely, this is not something as subtle as an instability. We'll need to walk through these steps more carefully next time.


DTT Templates:
H1:SUS-ETMX_L3_LOCK_L_IN1 / H1:SUS-ETMX_L3_LOCK_L_IN2: /ligo/home/louis.dartez/projects/20240311_new_darm_investigations/SUSETMX_L3_SS_new_darm.xml
H1:SUS-ETMY_L3_LOCK_L_IN1 / H1:SUS-ETMY_L3_LOCK_L_IN2: /ligo/home/louis.dartez/projects/20240311_new_darm_investigations/SUSETMY_L3_SS_new_darm.xml

Relevant logs:
- Old Matlab model revived (LHO:75584)
- Unsuccessful attempts in early 2024 (LHO:75308)
- Times spent successfully in new DARM state (LHO:75631)
- Calibration attempts in new DARM state (LHO:74977)

Comments related to this report

louis.dartez@LIGO.ORG - 00:39, Tuesday 12 March 2024 (76283)

Link

We went home after we lost lock but I forgot to request NLN on the way back up. The IFO relocked itself into NLN_ETMY and got stuck there. I tried going to DARM recover but overlooked that it'd try to go through new DARM to get there. This resulted in another lockloss, after which I requested NLN.

louis.dartez@LIGO.ORG - 10:39, Tuesday 12 March 2024 (76293)

Link

It turns out that last night's lockloss wasn't all bad; the IFO didn't lose lock while in the New DARM state (state 711)...it actually went down from state 712 which is RETURN_TO_NLN_ETMY. RETURN_TO_NLN_ETMY isn't particularly well-tested nor necessarily expected to work. The good news here is that we successfully transitioned into the NEW_DARM state last night.

This is great news! But we're not out of the woods yet. The transition resulted in a pretty hard kick (see NEW_DARM_worked.png) that we'd like to mitigate in future tests. We also only sat at NEW_DARM for about 52 seconds because I requested RECOVER_DARM, which took us in and out of NEW_DARM before losing lock. 

Lockloss Link: 1394259161


For next steps, we have integrators on the L1 and L2 LOCK banks that we're thinking of separating from their current filters and ramping them on after the initial transition. It's not clear yet if this will work.

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