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.
PRCL_CTRL reduction factor | Start A2L gain | End A2L gain | Start inferred position [mm] | End inferred position [mm] | Difference in beam position [mm] | |
PR2 P2L | 10x | -0.61 | -0.38 | -1.2 | -0.8 | +0.3 |
PR2 Y2L | very little | -7.40 | -7.45 | -14.9 | -15.0 | -0.1 |
PRM P2L | ~3.5x | 0 | 1.76 | unmeasured | 3.5 | N/A |
PRM Y2L | 5x | 0 | 0.52 | unmeasured | 1.0 |
N/A |
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:
Start Time | System | Name | Location | Lazer_Haz | Task | Time End |
---|---|---|---|---|---|---|
15:28 | SQZ | Terry, Kar Meng | Opt Lab | local | SHG work | 19:28 |
15:55 | FAC | Karen | Opt Lab | - | Tech clean | 17:55 |
17:25 | CDS | Fil | Ends, Mids | n | Look at/for equipment | 19:25 |
17:56 | VAC | Janos | FCES | n | Grabbing data in receiving area | 18:24 |
18:31 | ISC | Sheila | LVEA | n | Plug in excitation at PSL racks | 18:51 |
21:45 | SQZ | Terry, Kar Meng | Opt Lab | local | SHG work | 22:13 |
22:27 | PCAL | Dripta, Francisco | PCAL lab | local | PCAL work | 23:12 |
22:36 | SQZ | Fil | LVEA | local | Swap TTFSS box | 22:51 |
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.
We then went out again from 2223-2254UTC to swap the TTFSS box. I reaccepted the old -12dBm value for the beat note min.
WP 11859
Unit S2300259 installed.
This only worked for about 3hrs before we dropped out of Observing again at ~2utc (7pmPDT). I lowered the RFmin from -12 to -20 to buy us some more time.
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).
Back to Observing at 1858UTC.
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:
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:
Start Time | System | Name | Location | Lazer_Haz | Task | Time End |
---|---|---|---|---|---|---|
16:06 | VAC | Janos, Jordan | MX | n | CP dewar pumping | 16:51 |
16:07 | SUS | Camilla, Erik | remote | n | ITMX awg testing | 16:51 |
16:07 | SQZ | Sheila, Andrei | CR | n | SQZ meas. | 19:14 |
16:52 | FAC | Tyler, Eric | EX | n | Chiller yard alarm investigation | 17:11 |
21:38 | SQZ | Terry, Kar Meng | Opt Lab | local | SHG work | 23:32 |
23:30 | vac | jordan.janos | mx | n | turning off cp5 pump | 01:00 |
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).
22:48 UTC Lockloss. There was a 5-6 Hz oscillation in DARM and a little wiggle 10 ms before the lockloss.
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.
Pre April 24 | May 07 10:39 | May 07 11:03 | May 07 11:39 | Post April 24 | |
Start | -P move | +P move | -Y move | +Y move | |
SR3 P slider value | 438 | 81.9 | 798 | 438 | 438 |
SR3 Y slider value | -148.8 | -148.8 | -148.8 | -686.3 | 120 |
Here's a screenshot of the AS air camera when we were at the edge of our SR3 -Y move. The beam spot began to squish and spread across the screen a bit more.
Here are some trends with SR2 and SR3 M1 osems during these moves.
EDIT: Added a revamped table with the SR2 and SR3 OSEM changes. The deltas from these could all be found by subtracting the "Pre April 24" value from each column for each move. These values are the final position when AS_C power was recovered to nominal values.
Pre April 24 | May 07 10:39 | May 07 11:03 | May 07 11:39 | Post April 24 | |
Start | -P move | +P move | -Y move | +Y move | |
SR3 P slider value | 438 | 81.9 | 798 | 438 | 438 |
SR3 Y slider value | -148.8 | -148.8 | -148.8 | -686.3 | 120 |
SR3 P M1 osem | -290 |
-674 |
112 | -263 | -292 |
SR3 Y M1 osem | -616 | -592 | -640 | -1018 | -405 |
SR2 P M1 osem | -570 | 3040 | -1955 | 503 | 596 |
SR2 Y M1 osem | 11 | 34 | 28 | -2164 |
1160 |
Sheila, Jennie, Alena
Alena realised during her calculations of the spot positions on the OFI at different SR2 and SR3 alignments, that the osem value quoted in the table above for SR2 P M1 osem should be +570.
Sheila alos saw this when looking at osem trends.