camilla.compton@LIGO.ORG - posted 12:15, Wednesday 29 May 2024 - last comment - 12:15, Wednesday 29 May 2024(78115)
Looking at SQZ and IFO alignment and throughput on AS_C
Sheila, Camilla
As we were re-locking before commissioning time, we paused with ISC_LOCK in IDLE to check the alignment of SQZ and the IFO on AS_C.
Changed SQZ alignment, unsure if better or worse until we lock.
Checking SQZ:
- Single bounce ITMX, OM centering loops on and frozen (turn off inputs)
- Increased SEED injected power from 0.2mW to 76mW (same as April 16th 19:19UTC as in 77518 and 77518 plot)
- SQZ Manager LOCKED SEED DITHER
- ALIGN SRM, misaligned ITMs
- Previously injecting 1.28mW into HAM6 (OPO_IR_PD_LF with BeamDiv closed), now 1.25mW to 1.29mW, so similar power to before.
- Started with ~360 on AS_C NSUM
- Kept centered on AS_C with ZM4 while moving ZM5 to increase power on AS_C.
- Power was fluctuating a lot and it seems like we were mainly on a plateau.
- Accepted new alignments (scattering in IFO will tell us if they are better or worse, hard to tell if AS_C power really increased), attached in two sdfs, mainly pitch move then yaw.
- Got peaks of 384 on AS_C_SUM, average was 370 (want 380). Still loosing 2-3% from what’s expected.
- Similar power on AS_A and AS_B ~75.
- Plot attached.
Checking IFO:
- Single bounce ITMX 10W in, previously had 762e-2 on AS_C_NSUM. Today had 750e-2.
- With similar power into IMC 9.60W today, 9.61W prevoiulsy.
- Sheila checked the alignment sliders, we are ~15urad off in SR2 PIT witness channel. Everything else looks good (DC centering not on at time). Plot attached.
- Didn't change IFO alignment, started locking.
Images attached to this report
Comments related to this report
Naoki, Sheila, Camilla
We tried this alignment and the middle, mainly changing pitch alignment. Both of these were considerable worse. We went back to yesterdays alignment, hand adjusted ZM4/6 in ASQZ then ran SCAN_SQZALIGN. Sdf's attached accepted.
Back to 4.5dB of SQZ above 1kHz and our reference 100-100Hz. SQZ seems to still be injecting low frequency noise.
Kappa_C is 0.5% better in this new SRC spot, plot attached.
Images attached to this comment
