aLIGO LHO Logbook

H1 ISC (Lockloss)

daniel.brown@LIGO.ORG - posted 04:04, Friday 01 November 2019 - last comment - 04:32, Friday 01 November 2019(52865)

Relocking

Not sure why we lost lock around 01:20 PST, no one was poking the interferometer at the time.

X arm green wouldn't accquire, needed to adjust TMSX in pitch mostly
TRX offsets look high and not seeing any X arm flashes. FIND_IR didn't find anything. Went back through DOWN and TRX offsets got reset and IR was found.
Alignment was obviously terrible from AS air so I didn't wait, had to do MICH fringes and PRMI. SRM needed some pitching before it would lock.
Lost it in move spots, it was fast, not obvious culprits
Lost it in move spots again...
Did an initial alignment, however ASC DRMI is converging to an unoptimal alignment for RF 18 and 90 build ups. Manually fixed it after offloading.
- Lost it in engage ASC for full IFO,
- Stopped next time in prep for ASC and tried zeroing the error signals manually. CHARD yaw needed some adjustment again. SRC1 and SRC2 when zeroed did not match with good RF 18 and 90 build ups. We optimised for build ups and then set the SRC1 pitch and AS_C offsets to aim for this position.
- New offsets and moving things by hand seemed to help, we got through move spots
and finally we are back at NLN at 4:04 PST

Comments related to this report

georgia.mansell@LIGO.ORG - 04:32, Friday 01 November 2019 (52867)

The TR_Y offset also didn't get set correctly when we went through DOWN, I updated it by hand.
To minimise the SRC error signals in PREP_ASC_FOR_FULL_IFO for an alignment with good buildups, we changed:
- SRC1_P offset from -5 to -3.5 (this gets switched off as we power up anyway)
- AS_C pitch offset from 0 to -0.16
- AS_C yaw offset from 0 to -0.06
- This worked well for this one lock and hopefully don't mess up initial alignment or DRMI
We've updated the final SRCL offset added in LOWNOISE_LENGTH_CONTROL to 50 cnts