[Joe B, Louis D, Vlad B]
In an attempt to understand some of the strange low frequency sensing measurements made at LHO, we've been looking at alternative paths between sensing (meters of motion at the mirror) and actuation back on the mirror that might not go through the typical DARM filter bank.

While looking, we found that there is clear line coupling (i.e. lines above a certain height in DARM) to the DHARD_Y (and DHARD_P) ASC input. Interestingly, the PCALY transmitter channel (so the power on the PCAL laser before it bounces off the optic) is clearly seen by the DHARD_Y loop, shown in attached image.  The PCAL is a separate actuator from what the ASC loops use to actuate, and thus knows nothing about angle and length coupling.  One can also see all the other calibration lines also showing up very clearly in DHARD_Y as well.  If there is imperfect diagonalization of the ASC outputs such that they couple back into length, this effectively becomes a parasitic path parallel to DARM.

TITLE: 05/06 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 151Mpc
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 29mph Gusts, 19mph 5min avg 
    Primary useism: 0.08 μm/s
    Secondary useism: 0.15 μm/s
QUICK SUMMARY:

After a lockloss while holding ISC_LOCK at LOWNOISE_ASC to fix the TRANISTION_FROM_ETMX issue, we shifted focus to fixing the PRCL1 issue we were having with DRMI, so we were holding in DRMI for a bit. Once that was fixed we went back to holding in LOWNOISE_ASC. after that Commissioning was started.

• Change PSAMS from 7.5/0.55 to 8.8/-0.67
• Edits to SQZ alignment GRD
• Camilla/Erik troubleshooting ITM charge measurement injections
• Jitter injections
• NB injections
• SRCL FF gain adjustment
• PRCL injections
• HRTS injections?

We were able to get back to NOMINAL_LOW_NOISE at 16:50 UTC and got back into OBSERVING after Commissioners were done with their Commish wish list at 18:36 UTC.
H1 has now been Locked for 3 hours.  
Just unlock....

To get back into Observing, Jenne and Sheila reverted H1:ETMY_L3_LOCK_BIAS_OFFSET (with a 120s ramptime) from -7.5 to it's usual observing value of -3.0.

lscparams.py has been changed from -3.0 to -7.5. Maybe this is the 200V change Robert puts in 77633 but it looks like it's either been 320V or 115V recently, plot attached.

Naoki, Sheila, Camilla.

We edited SQZ_MANAGER.py state SCAN_ALIGNMENT_FDS to now automatically take go to Anti-SQZ (hard-coded value 100 with CLF phase negative sign), tune the asqz angle and then do the 4 degrees of freedom for ZM4/6 alignments.  When it's finished it will take sqz angle back to the original. Total time taken ~5minutes.

It's still best to run SCAN_SQZANG after this has ran to find the best angle for squeezing (another 2 minutes). Then take SQZ_MANAGER to FREQ_DEP_SQZ to go into Observing.

OpsInfo:  If squeezing is bad (see notes in wiki) and you have Jenne's permission, you can now optimize SQZ alignment by taking SQZ_MANGER to SCAN_ALIGNMENT_FDS, then SCAN_SQZANG before back to FREQ_DEP_SQZ. Total time ~8 minutes. SQZ Wiki updated.

Naoki, Camilla

Since we think that 8.8/-0.67 of ZM4/5 PSAMS is better than 7.5/0.6 as reported in 77268, we changed PSAMS from 7.5/0.6 to 8.8/-0.67 and ran SCAN_ALIGNMENT twice. It seems that the squeezing is more flat with 8.8/-0.67 and is similar to the reference in NUC33.

There was again coherence between DARM and SRCL in last night's lock, so I ran a SRCL injection and adjusted the gain of the FF. (FF attached)

I changed the gain from 1.15 to 1.12.  77570 and 77492 are other times this gain has been adjusted in the last few weeks.

The coherence of SRCL to DARM is low at the frequencies that we care most about for this injection (20-50Hz), but the noise in DARM is well above the ambient DARM noise.

Attaching SDF screenshot for both the SRCL and PRCL changes here.

Edit: the SRCL excitation was on from 18:18:57-18:22:00 UTC May 6 2024. 

FAMIS 20027

PMC reflected power continues to rise, as seen in recent weeks. The more rapid increase starting about 3 days ago looks to correspond to a drop in ISS diffracted power percentage; I'll adjust the ISS RefSignal at next opportunity to bring that back to the desired 2.0-2.5% zone.

Sheila, Camilla.

After this morning's windy lockloss from TRANSISITON _FROM_ETMX, we continued previous 77366 troubleshooting.

Sheila manually stepped though TRANSISITON _FROM_ETMX:

• We found that only the L1 history was cleared, giving unwanted outputs when we turned on L2 and L1 gains.
  • Sheila added a line to clear L2 history (line 5115: ezca['SUS-ETMX_L2_LOCK_L_RSET']=2).
• We then lost lock when turning off two DARM1 filters  (ezca.switch('LSC-DARM1', 'FM1', 'FM2', 'OFF')). This seems the cause of our glitch, attached shows this DARM1_SWSTAT change at the same time as the glitch on a successful lock.
  • FM1 "8^2:2^2" has a 20dB gain at low frequency and 10s ramp, but FM2 "MadHatter" has a 40dB gain and 0.09s ramp so is probably to blame.
  • Sheila notes that "MadHatter" used to be left on during the transition (74798, 75451). To check this, I see that FM2 was kept on though a successful transition from 75631, plot attached.
  • Sheila edited ISC_LOCK to leave DARM1 FM2 on during TRANSISITON _FROM_ETMX but turn it off during the next state:  LOWNOISE_ESD_ETMX, once we are already on NewDarm and effect of this low frequency filter is suppressed.
• After these changes, our locking was successful with no glitches: plot attached.

Attached is a screenshot showing a PRCL injection with and without the PRCL offset of -62 in PRCL1. 

PRCL offset off: 6/5/2024 17:19:13 UTC

PRCL offset on: 6/5/2024 17:09:19 UTC 

The PRCL offset doesn't make much of a difference to the DARM coupling, it may be a little worse with the offset off below 17Hz but a little better above 30 Hz. 

I've edited the guardian to no longer have this offset on, because there doesn't seem to be a strong motivation for it and we'd preffer not to have these digital offsets in.

Mon May 06 10:12:36 2024 INFO: Fill completed in 12min 32secs

Gerardo confirmed a good fill curbside.

Sheila, Jenne, Tony, Camilla

We've had locklosses in DRMI because the PRCL gain has been to high when locked on REFL1F.  Tony looked and thinks that this started on 77583, the day of our big shift in the output alignment.

Today we acquired DRMI with half the gain in the PRCL input matrix for 1F, this one acquisition was fast.  I've attached the OLG measurements for PRCL and MICH after the change. 

Tony is working on making histograms of the DRMI acquisition times, before the 23rd, from the 23rd to today, and eventually a histogram from today for the next few weeks to evaluate if this change has an impact on the DRMI acquisition times.

Jenne also found that it seems out POP18 build up seems higher in DRMI since the 23rd.

TITLE: 05/06 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Lock Acquisition
OUTGOING OPERATOR: Ryan S
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 15mph Gusts, 13mph 5min avg
    Primary useism: 0.04 μm/s
    Secondary useism: 0.14 μm/s
QUICK SUMMARY:

When I arrived the IFO was in REDUCE_RF45_MODULATION_DEPTH.
We made it up to Transition_From_ETMX before a lockloss.
The wind is fairly Gusty today.
 

DQSHIFT 20240429-20240505

Here is DQ Shift Report During this week :

• This week's cycle is around 73.82% and Sunday is the lowest during EQs happened
• Ground motion during this week relative high correspond to many EQs happened over the world and around US also
• There is misalignment of IFO laser but has been resolved.
• In HAM2 and HAM5 show many noises during the week, also strong violin modes occured from lower to high frequency
• H1:ASC-DHARD_Y_OUT_DQ, and H1:PEM-EX_VMON_ETMX_ESDPOWER48_DQ Channel always appeared during this week.
• Magnetic Noise and ESD Rack Shows High Noises (both in ETM X and Y)
• In several days, PSL Table also shows unstability, and Sunday 05/05 the humidity (chiller is quite high)
• In FScan , Saturday and Sunday has not show any plot, but on the Friday 05/03 shows a high line counts (>1000) and the largest among 1 month duration
• In Bokeh Plot, in lower frequencies 9around 80-150 Hz, some combs appeared in the same spot during this week)

TITLE: 05/06 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 151Mpc
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY:

IFO is in NLN and OBSERVING (6 hr 31 min lock). This is the longest lock in the last 24 hrs (4 brief locks in between).

I did not experience any of the issues that occured earlier in the week.

The squeezer phase angle had to be adjusted after 2-3 hrs (noticed the range going down, then noticed the SQZ not at its optimum) and was able to bring the range back up to what it was prior.
 

LOG:

None

IFO is in NLN and Observing as of 00:33 UTC (2 hr 35 min lock)

Nothing else of note

Anamaria, Robert

We photographed, from a second angle, the beamspot of a stray beam that I noticed last visit (76969 - Fig. 3 ). The photos (Figure 1) confirm that there is indeed a bright stray beam hitting, at a grazing angle, the bellows and other parts of the spool piece between HAM3 and the IMC tube.

I also wanted to measure the power of the stray beam that had been producing a large 48 Hz peak in DARM during early O3, in order to improve my scattering coupling calculations. This is the beam that reflects off of the PR2 scraper baffle and hits the illuminator viewport on HAM3, which we mitigated by inserting a black-glass viewport cover (52184). We were surprised by how bright the beam is, reaching 20 mW on the power meter (see Figure 2), even though we could not fit the whole beam on the meter. We estimate that the beam may reach 60  mW.

Finally, we made movies as we swept the ITMY compensation plate, hoping to see some indication of where the ghost beams are hitting, but did not. We will have to wait until Alena gives us the likely position of the CP ghost beams based on the angles that Anamaria showed us how to measure.

Jennie, TJ, Camilla

The Operator team has been seeing more locklosses at state 557 TRANSISITON _FROM_ETMX, more so when the wind is high. Times: 1397719797; 1397722896; 1397725803; 1397273349, 1397915077

Last night we had a lockloss from 558 LOWNOISE_ESD_ETMX with a 9Hz ITMX L3 oscillation, see attached. Compare to a successful transition (still has glitch).

Note that there is a glitch ~30s before state 558 in both cases.  H1:SUS-ETMX_L3_DRIVEALIGN_L2L and _L3_LOCK_L filter changes happens here. Are ramp times finished before these changes?

The timing of the glitch is 2 m 55 seconds after we get to state 557, this is the same time as in the 4 of the last 6  state 557 locklosses.