TITLE: 06/27 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Lock Acquisition
OUTGOING OPERATOR: Ryan S
CURRENT ENVIRONMENT:
SEI_ENV state: CALM
Wind: 9mph Gusts, 4mph 3min avg
Primary useism: 0.01 μm/s
Secondary useism: 0.05 μm/s
QUICK SUMMARY:
- We were stuck in PREP_FOR_LOCKING with ISC_LOCK stalled with IFO_NOTIFY and H1_MANAGER asking for help (10:22 UTC)
- As soon as I requested H1_MANAGER back to idle it released ISC_LOCK and we started to lock again
- At first glance I'm not sure why it was stuck
- The timer "to NLN with an initial alignment already having run" was why it was calling for help but it should have kept trying to lock itself?
14:46 UTC DRMI is struggling when ASC starts, I'm going to run a manual_IA
At the time of the request for help 10:22 UTC, we were in in CHECK_AS_SHUTTER where it was presumably stuck at SHUTTER_FAIL which I've encountered again at 15:22 UTC. It's been in that state since 09:05 UTC when we lost lock from 25Ws and the SHUTTER GRD reported "No kick... peak GS13 signal = 51.226"
The shutter did not trigger in this last lockloss, it looks like the light heading to the AS port was not high enough to trigger the shutter.
The lockloss_shutter_check guardian check for a kick in the HAM6 GS 13s anytime that we loose lock with more than 25kW circulating power in the arms. In this case we had just reach 100kW circulating power, so the guardian expected the shutter to trigger. This lockloss looks unusual in that there isn't a increase in the power going to the AS port right before the lockloss.
Ryan ran the shutter test and the shutter is working correctly now.
I think that this is probably the result of an usual lockloss happening at somewhat lower circulating power than usual. We should probably edit the logic in IFO notify to call for operator assistance whenever the shutter is in the failed state.
This is OK, the AS port went dark and stayed there for about 70ms or so after the lockloss and there was no excessive power surge that would have caused the fast shutter to be triggered.
The maximum power of ~1.4W was observed ~160ms after the lockloss, which is well below the threshold for the analog FS trigger (3 to 4W, I don't remember the exact number).
If something similar happened with 60W, though, FS might have been triggered.
Attached is the estimate of the power coming into HAM6 using two different sensors (PEM-CS_ADC_5_19 = HAM6 power sensor in the AS camera can which monitors power before the fast shutter, and ASC-AS_A_DC_NSUM after). Neither of these have hardware whitening, neither saturated (ASA was close to saturation but the HAM6 power sensor saturation threshold is about 570W when beam diverter is open, 5.7k if closed).
Note that the calibration of the PEM channel is a factor of 10 smaller than that in the observation mode (0.177W/ct, see alog 81112 and git repo for lock loss tool) because the beam diverter (90:10) was open.