Robert and Anamaria found that there are some stray beams in HAM3 (alog 77631).  As part of understanding where that could be coming from, Anamaria suggested measuring our position on PR2.  TL;DR: we're the same 15mm off center in yaw that we have been, but now maybe we're starting to realize that it's too much.

Throughout O4, it looks like we've measured the beam position on PR2 three times (including today).  April 2023 (alog 690225), Dec 2023 (alog 74789), and today (this alog). 

As with the previos times, changing the PR2 A2L coefficients doesn't really seem to effect the line height in DARM, but I can reduce it in PRCL_CTRL.  I didn't confirm that PRCL_IN1 agrees on minimum line height with PRCL_CTRL, but I don't have reason to guess that they'd be different from one another.  Today I used 29 Hz, with a line amplitude of 1 in the ADS oscillator.  This made  a line in DARM about 100x above the ambient for the pitch excitation (maybe a little less than that for the yaw excitation).  Also, the peak in DARM seemed quite broad, with upconversion wings around it, more than I expected.  I don't recall seeing such strong upconversion when doing this similar measurement recently in alog 77443.

I also measured the spot position on PRM, again with a 1 count amplitude at 29 Hz.  The peak in DARM was much less broad than it was for the PR2 excitations. PRM started with no A2L gains at all. 

All of my fine-tuning step sizes today were at the level of 0.03 (which is 3x smaller than my SR2/SRM steps a few weeks ago). So, indeed the PRC optics seem a little more sensitive to A2L coefficients. I left both PR2 and PRM with the coefficients I measured today. 

Talking through numbers out loud with TJ, Corey, and Oli, and looking at D1002640 which shows the 70mm aperture size that Minhyo quotes in alog 77637, it sure seems like this is a plausible explination for the source of the light that Anamaria and Robert found. If the beam is off center on PR2 and the baffle by about 15 mm, and then 15mm away from that is the point at which, if we were clipping, we'd see a few tens of mW clipped, that clipping point total of 30 mm is starting to sound suspiciously similar to the baffle aperture radius of 35 mm. 

This motivates that perhaps we really should consider trying to get closer to center on PR2. So far we haven't done so, because there are lots of alignment follow-ons that would also need to happen for the leakage beams in transmission of PR2 (eg ALS to ISCT1, POP ASC beams, POP LSC beams).  But, the only one of those that we actually need in full lock is the LSC POP, so we could make some moves and as long as we're staying on LSC POP, we could see if that improves things enough to motivate making a new alignment permanent (and doing all the follow-on not-easily-reversible alignments).

TITLE: 05/09 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 154Mpc
INCOMING OPERATOR: Corey
SHIFT SUMMARY: Commissioning time this morning and two brief out of Observing times this afternoon to fix the SQZ TTFS box. Other than that it has been straight forward today. Locked for 13 hours.
LOG:

• 1600 Commissioning start
• 1858 Observing
• 19250-1958 Briefly out of Observing to fix SQZ fiber TTFSS issue.
• 2223-2254 Briefly out of Observing to swap TTFSS SQZ box

TITLE: 05/09 Eve Shift: 2300-0800 UTC (1600-0100 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
OUTGOING OPERATOR: TJ
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 20mph Gusts, 16mph 5min avg
    Primary useism: 0.05 μm/s
    Secondary useism: 0.13 μm/s
QUICK SUMMARY:

H1 had just come back into Observing by TJ as I walked in (w/ H1 locked 13hrs).  Not much else to pass off from TJ (he mentioned LLO have been recovering from a power glitch most of today...but there  are signs of life from L1!).  Winds have steadily increased over last 8hrs with gusts touching 25mph now (but forecast has calm-down after sunset).  Microseism continues a slow trend down to/below the 50th percentile.

The SQZ fiber beatnote has been dropping since the new box was installed this past Tuesday. It dropped below threshold and the autolocker turned off, but held lock. Sheila bumped this min dB to -14 for now, but we will talk with Fil about replacing that box soon since it doesn't look OK. See second attachment.

In March, Louis and Gabriele found an AS_A yaw offset that reduced the coupling of DHARD Y to DARM (76407)   We've been running with this offset since.

Today I quickly checked that this is still the offset that minimizes the coupling, it still is close to the right offset.

Thu May 09 10:10:18 2024 INFO: Fill completed in 10min 14secs

Jordan confirmed a good fill curbside.

Gabriele looked at the nonstationarity of the SRCL coupling in 77666, and proposed DHARD P as a degree of freedom that could be responsible. 

This morning I measured the SRCL to DARM transfer function with and without a small offset in the DHARD P error point.  I chose an offset of 10 counts which is about the rms of the DHARD P error signal (spectrum attached). This changed the coupling from SRCL to DARM (with the feedforward on) by 20%.  So indeed it seems that we need to reduce the RMS of the DHARD P loop to have a stationary SRCL coupling.

Excitation with offset on: 5/9/24 16:16:52 UTC - 16:20:39 UTC  with offset off we took a longer stretch of data in case it is useful to look at: 16:21:47-16:34:18 UTC.

Out from 1600-1900UTC (9-12PT).

TITLE: 05/09 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 155Mpc
OUTGOING OPERATOR: Ryan C
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 8mph Gusts, 5mph 5min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.13 μm/s
QUICK SUMMARY: Observing for 4.5 hours. The relock was full auto, but lost lock at DRMI 3 times before it finally worked.

TITLE: 05/08 Eve Shift: 2300-0800 UTC (1600-0100 PST), all times posted in UTC
STATE of H1: Lock Acquisition
INCOMING OPERATOR: Ryan C
SHIFT SUMMARY:

Random lockloss just before shift and one in the 2nd half of shift.  Reacquisition for both was straightforward.
LOG:

• 2318 SHG work complete for day in Optics Lab (Terry,KarMeng)
• Locking Notes:
  • After lockloss, Sheila and TJ took a look at SRC alignment with regards to the OFI.  Then jumped right in to locking H1.
  • X&Y arms needed INCREASE FLASHES.  Had to go to CHECK MICH, and tweaked PRM in yaw mostly for PRMI; then DRMI locked automatically.
• 2327 Cleared test points to get rid of PR2 drive align channels which had been up a few days.
• 2329-2344 Disconnecting CP5 pump at MX (jordan, janos)
• 0157-0210 Drive over bridge and 0210-0250 drove down Yarm (andrei)
• 5:00 Lockloss
  • Y-arm needed increase flashes, and DRMI needed PRMI to run & then it was fully automated after.

Much different evening from last night.  After the lockloss before the shift, H1 was able to get all the way back up to NLN without an alignment (just tinkering for ALS/PRMI alignments).  H1's been locked for 4hrs and all is well.

Attached are monthly TCS trends for CO2 laser and HWS.  Nothing notable of note in the trends.

TITLE: 05/08 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Lock Acquisition
INCOMING OPERATOR: Corey
SHIFT SUMMARY: Locked for 10.5 hours before a sudden lock loss just happened. There was some commissioning time this morning which bumped our range up a bit, so hopefully when Corey gets it back up we will be back above 160 again.
LOG:

• 1531 Out of Observing for planned calibration and commissioning
• 1913 Observing
• 2248 Lock loss

We lost lock, and took that as a chance to go back to our SR3/SR2 alignments from before April 23rd.  The attached screenshots are of the AS camera once we went back to the old alignment, and then after we moved SR2 to center the beam on AS_C.  You can see that the beam has fringes when centered on AS_C. 

In order to center on AS_C we had to move -54 urad in pitch, (which would move the beam on SRM upwards), and -27 urad in yaw (moving the beam in the -X direction on SRM)

This is a larger shift than what is suggested by Jenne's look at times when we ran AS_C centering in 77690 .

TITLE: 05/08 Eve Shift: 2300-0800 UTC (1600-0100 PST), all times posted in UTC
STATE of H1: Lock Acquisition
OUTGOING OPERATOR: TJ
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 17mph Gusts, 12mph 5min avg
    Primary useism: 0.04 μm/s
    Secondary useism: 0.16 μm/s
QUICK SUMMARY:

H1 just had a lockloss as I arrived and Sheila/TJ were investigating alignment into/around the OFI.  Winds are lighter than yesterday thus far. Microseism also turned down from the step up 24hrs ago (now hovering just above the 50th percentile).

Alena Anayeva has been working on some zeemax modeling to help us understand what happened when our output arm seems to have changed on April 22/23rd. 

She has been using shifts in alignment based on slider numbers as reported in 77388, but the shifts that this is giving her are too large. 

This is a quick look at the slider calibrations.  There is a discrepancy for SR2, the slider calibration agrees with the M2+M3 osems, M1 osems are reporting a 62% smaller shift. For SR3, the sliders and osems agree to within 10%.

After the large shift we have been falling off the SR3 optical lever, so that is not a useful comparison.

Jenne D, Ryan S, Camilla C, TJ S

Today in a single bounce 10W configuration we set SR2 to center AS_C with the SRC2 ASC loops via the ALIGN_IFO guardian in the SR2_ALIGN state, then moved SR3 in steps to see how our AS_C power would change in different positions. We found that there is an area, or spot, that we lose significant throughput to AS_C, but moving around this spot in any direction recovers our nominal single bounce power. This is followup from Jenne Driggers SR3/2 move (alog77388) to bring back our power at the AS port on April 24th, and Jennie Wright, Minhyo, and Sheila's efforts searching in yaw to find where we are losing the power (alog77513). This time we went further than Jennie W and team went and managed to get back almost all of the AS_C sum back. Almost all because just before we got there we starting running into a different, perhaps clipping, issue that changed the shape of the AS air camera in a much different way than when around this spot.

More details:

We started out by reverting the alignment to a time during DRMI locking from the Tuesday morning of April 23. We then brought up tried to move SR2 and SR3 as was done previously, then Jenne suggested that we turn on SRC2 to have SR2 follow our SR3 moves and keep AS_C centered. This worked great along with a little extra SRC2 gain to help move things along faster. Moving in pitch in either direction yielded fairly quick power gains (trends SR3 -P move & SR3 +P move). Jenne suggested that we try to go further in yaw than the Jennie W. team did to see if it ever improves, and we were able to get AS_C almost back after ~550urad in SR3 (trend SR3 -Y move today, and SR3 +Y move April 24 ). If I had the time I'd love to make a nice graphic to show where we can't go but we'll have to deal with this table for now.