STATE of H1: Observing at 134Mpc. IFO has been locked for 18h24

Sat Jul 15 10:05:35 2023 INFO: Fill completed in 5min 35secs

TITLE: 07/15 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: Observing at 132Mpc
SHIFT SUMMARY:

H1 & L1 were up the entire shift (so I did not get a chance to run the quick broadband calibration measurement---a good problem to have with such well-behaved instruments!).   Passed this info on to Camilla in case she gets a chance to run the short measurement (i.e. "pydarm measure --run-headless bb"

Oh, and it's almost 80degF outside!!!!
LOG:

• 1034 & 1044: Brief INVALID/NOT_CONNECTED_ERROR alarm for DUST Alarm Handler (pop-up roughly states:  "Channel Access Exception:  Virtual circuit unresponsive  Context:  h0epics.cds.ligo-wa.caltech.edu [xxxxx]").  This would briefly show up on the CDS Overview as an H1EDC RED dot due to channel drops.
• 10:56:09 Big broadband glitch w/ EX & DCPD saturations on Verbal w/ range drop to about 13Mpc.

TITLE: 07/15 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 133Mpc
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 3mph Gusts, 3mph 5min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.04 μm/s
QUICK SUMMARY: Locked in NLN for 14h22. Range been between 132-136MPc over the last hour.

Corey notes if LLO goes down we should run the pydarm measure --run-headless bb command following the Taking Calibration Measurements Wiki

Smooth sailing for H1 (& L1) with summer twilight skies & outside temp of 71degF.  Just had a huge glitch a couple minutes ago, but no biggie.  

TITLE: 07/15 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: Observing at 134Mpc
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 6mph Gusts, 4mph 5min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.04 μm/s
QUICK SUMMARY:

Receiving a nicely locked (6.5+hrs) H1 from RC.  Received notice of possible calib meas I can run (if L1 drops), and notice of alsx pll autolocker toggle needed for Camilla's last lock.  Balmy 78degF out.

TITLE: 07/14 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 132Mpc
SHIFT SUMMARY:

• We've been locked for 6:25
• Handing off to Corey

DIAG_MAIN flashes the messages PSL ISS difracted power is low every few minutes, this is known and will be fixed soon by Jason

Back into NLN at 0:34UTC in Observing at 00:44UTC, LLO was relocking around the time so Robert went out to do some PEM scatter work in the LVEA while we waited for them to get back and we damped violins.

GRB_Short E417374 01:44 UTC

LOG:                                                                                                                          

STATE of H1: Observing at 132Mpc

Back into NLN at 0:34UTC in Observing at 00:44UTC. Everything has been stable and calm. (Forgot to click post)

Closes FAMIS 25590

CS:

Fan5_170_2 is a little noisy and Fan_5_170_1 is the highest in the CS at just under 0.4

OUT:

EY_Fan1_470_1 looks like something happened to it yesterday, it has dropped a bit since but is still the highest for the OUTs at around 0.3. MY_FAN2_270_1 is quite noisy.

[Jenne, Naoki, Brina, Caden, Robert, Lance, Camilla]

Since alignment changes were so impactful yesterday (alog 71302) and we still have higher noise than when OM2 was hot last week, and also higher noise than our April 60W times with cold OM2 (eg, Elenna's alog 71284 yesterday), we tried some alignment shifts today with some PEM vibration injections going, to see if we could find a better alignment.  For now, we've left the IFO with the same settings it had last night since there's nothing that's significantly better.  Nothing we've found comes close to matching the broadband (good) noise level of the April 60W time, or the last week hot OM2 times.

• The camera servos are very slow, so I wanted to switch back to ADS. However, just asking the camera servo to do so dramatically changed the alignment of the IFO; arm buildups were going down and some of the ASC looked unstable.
  • There isn't a handy way to switch back to the camera servos without having the offsets be set to your current position, so we used the Camera servo guardian to go back to using the cameras (which reset the camera offsets), and then Naoki by hand set the camera servo offsets to where we had been overnight.
  • I then turned on the A2L excitations (but not the servos), and changed the A2L gains to zero the error signals.
  • Then we again used the camera servo to switch over to ADS, and we saw much less change in the circulating power buildups. The third attachment shows the situation at that time. 
    • Note that this means that after a long time of thermalization, the place the ADS would keep the IFO is different than the place the camera servos keep the IFO.  I *think* that it's better with the camera servos, since that's where we're maintaining better buildups. 
• Once back on ADS, I tried moving A2L setpoints to see if that would change the jitter peak around 120 Hz, and see if it would change the broadband excess noise we seem to have. I also tried changing the AS36Q yaw offset, but I think that even with A2L moves, the current value of 35k count offset is the best.
  • I can pretty dramatically change the circulating arm powers.  In particular, changing the ETM Y2L set points was giving us an extra 10kW circulating, but that seemed to not be the best place.
• Robert reminded me / pointed out that the 120 Hz jitter peak isn't necessarily the only thing to be mindful of, since he can likely move that by adjusting damping and weights on the PSL periscope, so we should probably focus on the broadband noise increase and try to fix that. Unfortunately, none of the moves we made today seemed to affect it. 
• Around 21:50:00 UTC seemed to be a pretty good time, but again not better than with the hot OM2.
• We ended things by trying to improve some of the low freq by changing the ITMY A2L gains.  The second attachment shows where I left things when we lost lock due to a closeby earthquake. 

The first attachment shows a big-picture of the moves we made today. 

Daniel points out that the time with OM2 hot may have been some of our best-ever sensitivity around 70 Hz.  It would be helpful to have a plot like alog 71309, but including Elenna's time from April 6th, to see if pre-O4 we ever had as good of sensitivity around 70 Hz. 

It's also a little tricky to compare our HWS data using our plotter to what Elenna and Cao posted yesterday.  It would be helpful to either have the times from Cao's plot, or have Cao plot where it looks like our ITMX spot was at 21:50 UTC today. 

We wanted to check if the value of the H1:LSC-IFO_TRIG_INMON lower threshold was possibly too low. If once the detector lost lock the IFO_TRIG_INMON channel took too long to reach its minimum trigger value (325), the violin damping gains would stay on too long and could be the cause of the violins ringing up so high, which started happening after the June 27 maintainance (71063).

(Uploads 1+2) I took the channel H1:ASC-AS_A_DC_NSUM_OUT16 to pinpoint when the detector lost lock, and plotted it alongside H1:LSC-IFO_TRIG_INMON. When the H1:LSC-IFO_TRIG_INMON channel value drops below 325, the damping for L2 and L3 should turn off. Comparing a lock loss before June 27 to after, both of which were from long lock stretches, it looks like for both times (and for the other lock losses I looked at), the time between the lock loss occuring and the damping turning off was about the same, between 1-1.5 seconds.

(Upload 3) There is also a clear difference pre- and post- June 27th in the amount of gain used to damp the violins.

TITLE: 07/14 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Lock Acquisition
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 13mph Gusts, 9mph 5min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.05 μm/s
QUICK SUMMARY:

• CDS/Vac/Dust looks good, low wind, we had a few smaller earthquakes roll through today
• Currently relocking, we'll probably be back to Observing in an hour or two depending on the violin damping (they look high as of 25W)

TITLE: 07/14 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
SHIFT SUMMARY:

15:06 Took over from Corey, detector Locked and in Observing for 1:50

16:16 Moved out of Observing to change ACS channel value

16:18 Lost lock (71324)

18:27 Back into Observing (stuck damping violins in OMC_WHITENING for 1 hour 8 mins)

20:01 Moved out of Observing for Commissioning (71331)

22:29 Lost lock during commssioning due to possible local earthquake (71336) - commissioning ended early due to lockloss

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Lockloss at 22:29: Lockloss tool

Most likely due to local earthquake but PeakMon (attached) didn't get above 800.

Occurred during Commissioning while PEM acoustic injections were happening.

WP11290 Revert LALAPPS to fix memory leak

Erik, Dave:

At 13:21 PDT Erik restarted the psinject CW process on h1hwinj1 after downgrading the libSIStr,so library file. This has fixed the memory leak h1hwinj1 has had since its upgrade when tconvert was replaced by gpstime.

Between 13:21 and 14:48 there has been no additional memory allocated, before memory was used at a rate of 3.5MB/min.

We will run with this over the weekend and if it all looks good I will revert the h1calinj SDF change make to permit INJ_CW GAIN and TRAMP changes while in observation (WP11304)

6 hour trent of INJ_CW with restart shown in attachment.

Have scheduled commissioning work this afternoon from 20:00UTC to 23:00UTC. Mainly PEM and alignment work.

Dan Brown, Cao, Kevin K., Elenna

I made a plot comparing the high frequency DARM spectrum around 10 kHz comparing our current 60W configuration to the configuration we had the last time we were at 60W, specifically April 6. These plots were both made well into each lock, so the thermal transients had settled. I believe they are an apples-to-apples comparison of the high frequency region for these two locks and IFO configurations. Three features stand out as different between the two spectra: the 2nd order HOM peaks are not in the same location, they are not the same height, and the overall DARM spectrum is lower in the blue trace (April), than the red trace (now). This indicates that the arm modes are not as well matched now as they were in April, and the frequency noise noise now is higher by a factor of 1.7 than it was in April.

If nothing else had changed in the IFO, we should have been able to successfully revert to the blue trace by powering down and reverting all other settings.

I think the reason we haven't been able to revert to the previous 60W state is related to the mysterious changes that occurred on and after May 19 when the HVAC caused many issues. Whatever changed in May caused us to ring up a PI, increased the jitter noise, and changed our mode matching. My hypothesis is that the alignment shifted in some way. Unfortunately none of the suspension, oplev or ISC signals indicate an alignment shift.

I asked Cao to take a look at the ITMX hartmann wavefront sensor. Cao made the following two plots: one showing the center of the beam position in x (yaw) and y (pitch), and the other showing a heat map of ITMX. The two times they compare are the two locks I compare in my DARM plot: the blue "old" trace from April 6, 60W, and the orange "new" trace showing now at 60W. The beam position has changed, and the heat map shows that we are heating the ITMX point absorber more than we did previously.

If the spot has moved closer to a point absorber, this would explain our increase in jitter. If the spots on the test masses are shifting, this could also affect PIs like the 80 kHz that may be spot dependent. A spot position change could also aggravate the point absorber to where the radius of curvature and substrate lensing would change enough that our mode matching solution via the ring heaters would no longer be sufficient. We only have evidence that the spot has changed on ITMX, but there is a chance that it could have changed on the ETMs as well, where we know the 80 kHz acoustic mode is located. Unfortunately, we don't seem to have any good signals that could track this on the ETMs, so we are flying blind.

Overall, one of our goals (especially in powering down) is to get the IFO mode matched well enough that we can reduce frequency noise and be able to achieve a good level of squeezing. I think we should consider moving the spots on the test masses, especially ITMX. Those who remember, you might be thinking "we already tried this and saw no effect!" However, we have a different IFO now, and I think it is worthwhile to try moving further away from our point absorbers.

Mode matching of the single bounce beam to the OMC is really bad and we don't know why. We don't even know the beam shape of the single bounce beam hitting the OMC. I constrained the beam shape by looking at the OMC scan data.

There are many OMC single bounce scans but the most recent two w/o RF SBs, one with cold and the other with hot OM2, were carefully analyzed by Jennie to resolve 02 and 20 mode as separate peaks (alogs 70502 and 71100), so I used them here.

If you just want to see the results, look at the third panel of the first attachment.

X-axis is the normalized waist position difference, Y-axis is the normalized waist radius difference. From the measured cold mode matching loss of 11.5%(!!) and hot loss of 6.2%, and the fact that the loss changed by only changing the ROC of OM2, the beam parameters hitting the OMC were constrained to two patches per each OM2 ROC. Yellow is when OM2 is cold, blue is when OM2 is hot. Arrows show how cold (yellow) patches are transformed to hot (blue) patches when OM2 ROC is changed by heating.

Note that we're talking about inconceivably huge mismatching parameters. For example, about -0.3 normalized waist position difference (left yellow patch) means that the waist of the beam is ~43cm upstream of the OMC waist. Likewise, about +0.3 normalized waist radius difference  means that the beam waist radius is 690um when it should be 490um.

We cannot tell (yet) which patch is closer to reality, but in general we can say that:

• The beam is too big (Normalized waist radius difference is positive) when the OM2 is cold.
• If the reality is more like the patches on the left half of the plot, making ROC even smaller will give us a better matching.
• If on the right half of the plot, changing ROC won't do much, we need to change the distance between OM2 and OMC.

There are many caveats. The first one is important. Others will have limited impact on the analysis.

• We don't know yet if this "MM loss" measurement is really a fair representation of mode decomposition of the beam hitting the OMC. If for example there's a position-dependent loss  (e.g. dust particulates on the OMC mirrors close to the center of the beam spot, it doesn't have to be on HR, it could be on AR of input or output coupler) the analysis will be totally off. Separate evaluation needs to be made to make sure that this isn't (or is) the case.
• I assumed that the distance between OM2 and OMC waist is as designed (~37cm). This sounds like a fair assessment as the error of a few cm hardly matters (1.4cm error corresponds to the normalized mismatch parameter of 0.01).
• I assumed that the measured MM loss could have +-10% fractional error, i.e. loss=(1+-0.1)*lossMeasured.
• I assumed that the ROC is 2m cold and 1.75m hot, but I haven't checked the thermistor, so these numbers could be off, which could have a minor impact.
• I assumed that the beam is round w/o astigmatism.

Moving forward:

• It would be difficult to down-select one of the two pairs of patches by going to the middle heating setting. It might be possible to use ITM central heating or maybe PR3. I'll look at the Gouy phase of these relative to OM2.
• Even if we can down-select, that won't give us any REAL guidance as to what we should do. We WILL see what to do to make the single bounce matching better, but doing so w/o understanding why is a risky thing. Besides, doing so might make our jitter coupling in full lock worse.
• Aforementioned characterization of the schmutz. For that matter, I suddenly remembered that Daniel wanted to see the QPD/OMCREFL ratio when I was calibrating the OMCREFL. That might help or not but I'll pull the data.
• We can do a similar analysis for full locked IFO beam.