Broadband PCAL measurement taken this afternoon starting at:

PDT: 2024-04-05 15:19:02 PDT
UTC: 2024-04-05 22:19:02 UTC
GPS: 1396390760

Measurement ran for ~5 minutes.

FAMIS 26238

I added the PDWD to this script after the first time I ran this.

Laser Status:
    NPRO output power is 1.811W (nominal ~2W)
    AMP1 output power is 66.96W (nominal ~70W)
    AMP2 output power is 137.3W (nominal 135-140W)
    NPRO watchdog is GREEN
    AMP1 watchdog is GREEN
    AMP2 watchdog is GREEN
    PDWD watchdog is GREEN

PMC:
    It has been locked 3 days, 3 hr 59 minutes
    Reflected power = 17.61W
    Transmitted power = 108.3W
    PowerSum = 125.9W

FSS:
    It has been locked for 0 days 4 hr and 45 min
    TPD[V] = 0.8019V

ISS:
    The diffracted power is around 2.3%
    Last saturation event was 0 days 1 hours and 29 minutes ago

Possible Issues: None reported

We've added a new path to the CAMERA_SERVO guardian which will now be the default, where we set the camera offsets to fixed values stored in lscparams rather than reseting it each lock based on the ADS set points.  This is because we found last night that the build ups were better at a different offset for the BS camera 76961

We caused one lockloss doing this switch, which we think is because I changed the order of doing the switch.  We've edited the guardian in a way that we think should not have a large transient.

Eric, Camilla, Naoki

Attached are some plots showing several FOM for the impact of changing the ZM4 and ZM5 PSAMS on the squeezing seen in DARM. The axes of these plots show the strain gauge readouts for the PSAMs since the piezos are known to have issues with hysteresis. Our nominal setting is (7.2, -0.72).  

Initially we had relatively little reason to believe that the current settings were optimal.  Both PSAMS were centered in their range in terms of voltage after offloading during the commissioning break.  We decided to start with a broad scan (see PSAMS.jpg) and chose to prioritize regions not covered by the PSAM scan in 76507.  We Note, however, that the scans in 76507 were completed prior to the recomissioning of the SQZ alignment optimization scripts which may impact those results to some degree.   We learned that the current point is actually not too far from optimal.  

We then narrowed in on points closer to (7.2, -0.72) (see PSAMS_zoom.jpg).  It looks like there may be a point which produces slightly higher levels of ASQZ.  We would like to explore the area around this PSAM setting more carefully.  

A few comments:

• Our process was as follows when optimizing for a new PSAM value:
  1. Change the voltage on one PSAM optic.  This tends to pitch the optic a bit; this is a known issue with the PSAM suspensions.
  2. Roughly restore the alignment by tilting the PSAM optic to recover the old values in the witness channels. 
  3. Tune the sqz angle to antisqueezing
  4. Optimize the alignment by running a alignment scan to maximize antisqueezing.  
  5. Repeat with the other PSAM if required.
  6. Take DARM spectra with the squeezing angle optimized for Squeezing and then Antisqueezing at high frequencies
• We found that step 2 above was much less effective for ZM5 than for ZM4.  We speculate that this may be due to the fact that the beam is not completely centered on the ZM5 optic, an observation made during the PSAM offloading in January.  
• For now, we are getting our squeezing/asqueezing levels from dtt, but are working on scripting the analysis to use BLRMS data instead.

I took some sqz and no sqz quiet times from yesterday to try and make a plot of the excess noise agaion as in this entry. As Vicky thinks this correlated (non-quantum) noise is getting better.

For the first image I compared calibrated DARM from  this week with the same measurement from March and from 04a.

Grey is from 04a, purple is from previous slide with March data, yellow and green are from this week.

What we can get from this plot is that this non-quantum noise is different from lock to lock and we are not sure why.

Between 80 and 190 Hz the excess noise seems to now be better relative to March and 04a.

But the fact the noise without squeezing changes so much in a week is confusing.

In the second plot I have just compared three no squeeze quiet times from this week and it easier to see that the noise is not consistent below 200Hz.

Fri Apr 05 10:05:56 2024 INFO: Fill completed in 5min 53secs

Gerardo confirmed a good fill curbside. TCtrip raised to -100C while this cold spell lasts.

FAMIS 19972

pH of PSL chiller water was measured to be just above 10.0 according to the color of the test strip.

S. Dwyer, R. Short

During H1's locking troubles this morning, we decided at one point to start an initial alignment from the start since DRMI was not locking. While the ACQUIRE_XARM_IR state was running during the input alignment steps, Sheila noticed the LSC-TR_X signal was far off from zero with no light, meaning there was a dark offset that needed to be fixed. I took the mode cleaner offline so we could observe the dark signal on the POP_A_RF45 photodiode and applied the negative value of that to the offset for both the I and Q segments. This allowed XARM IR to catch quickly, and input alignment completed without issue (contrary to its behavior in recent weeks). Sheila has updated the hard-coded offsets in ALIGN_IFO's PREP_ARM_IR state generator (lines 770-771) and included a note that these need to be updated periodically when input alignment has trouble.

This should fix the troubles we've been seeing with input alignment and serves as a reminder to check for any erroneous changes to dark offsets if we notice issues with alignment steps.

https://ldas-jobs.ligo.caltech.edu/~gabriele.vajente/bruco_1396341217_GDS_CALIB_CLEAN/
DHARD_Y is pretty bad, much worse than usual. Probably need a retuning of A2L

TITLE: 04/05 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Earthquake
OUTGOING OPERATOR: TJ
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 4mph Gusts, 3mph 5min avg
    Primary useism: 0.04 μm/s
    Secondary useism: 0.32 μm/s
QUICK SUMMARY: H1 is currently running and initial alignment following downtime for about 5 hours from an earthquake (mentioned in the owl shift alog).

• Wind and microseism are low
• All other systems nominal

The IFO lost lock at around 1015UTC, then while running an alignment, a 6.8M earthquake from the pacific rolled through, tripping ST1&2 ITMY ISI. This also put SEI_ENV into error for requesting the EARTHQUAKE state from SEI_CONF, which for reasons is actually EARTH_QUAKE. I'm waiting for the ground motion to come down a bit before finishing the alignment and starting to relock.

TITLE: 04/05 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 150Mpc
INCOMING OPERATOR: TJ
SHIFT SUMMARY: We've been locked for 23:18 as of 07:00UTC

Lock#1

• 23:00 UTC - 00:58 UTC Observing
  • SQZer unlocked possibly from the PMC-PZT voltage dropping too low, but the SQZ_MANAGER relocked everything then prompted me to "Return to FDS" so I requested FDS and was able to return to Observing at 01:14UTC. SQZing looked a little worse at high freq after the relock
  •  Reloaded SEI_ENV during this which caused it to lose FAIL/lose connection due to a TypeError of "NoneType is not iterable"
    • I think the error came from a small typo? An extra underscore?
• 01:14 UTC - 07:00 UTC Observing
• Two small local EQs came through around 1:45UTC, from 4.8 & 4.5 Northern California, not enough motion for SEI_ENV to transition

LOG:                                                                                                            

We briefly dropped from Observing due to the SQZer losing lock from 00:58 till 01:14 UTC. I reloaded SEI_ENV during this time which caused it to fail due to an index error, so Dave and I reverted the latest changes and restarted the node.

We've been locked and observing since, lock time of 19:20 as of 03:00UTC

EX Cryobaffle

In January we damped the EX cryobaffle through a viewport (75553) because it had not been available for damping during the O3-O4 break and because the scattering noise from it increased with beam power (70808). The baffle has a 4 Hz resonance that matched a 4 Hz mode of the isolation system of one of the HVAC fans, making it particularly noisy early in the run, until we switched fans.  Figure 1 shows that, after damping, about five times more motion of the beam tube is required to produce about the same level of noise in DARM.

Input Arm

During the break, we doubled the angle of the MC baffles in the input arm, so that there would be no specular reflection paths between optics, we added more damping to the MC baffles, added nozzle baffles to each of the nozzles with blank-off flanges, and added an unplanned baffle for a glint (75726).

Figure 2 shows a frequency sweep, injected by a speaker, and the resulting noise in DARM before and immediately after the break. The noise produced by injections above 15 Hz, is greatly reduced immediately after the break. However, we had also hoped to better reduce the noise produced by injections below 15 Hz. I spent last week looking into glints that I could see in the chamber and other potential sources of the residual coupling below 15 Hz. I found that  I could greatly reduce the residual coupling by changing the yaw of the ITMY compensation plate by 50 microradians. The last pair of spectrograms in Fig. 1 shows that this CP angling further reduced the coupling to levels that we had hoped to achieve. 

Figure 3 shows the elimination of noise for a 13.1 Hz injection after angling the ITMY compensation plate in yaw. The second page shows that there is repeatable structure at about 20 microradians in the coupling, suggesting that there are multiple ghost beams or, more likely, multiple retroreflecting structures.  The third page shows a bright light on the wall of a spool piece that bears further investigation.

TITLE: 04/04 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Commissioning
OUTGOING OPERATOR: Corey
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 11mph Gusts, 8mph 5min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.28 μm/s
QUICK SUMMARY:

• Winds calming down
• SQZ commissioning is wrapping up
• We've been locked for 15:18

Attachment 1 - Unsqueezed (left) vs. squeezed (right) DARMs in ER16, with respect to O4a. Like Gabriele's plots, the ratios on the bottom show a given trace / O4a reference, so ratio > 1 means more noise now than O4a.

• (left) Last night's no-sqz time 76872 looks quite similar to O4a around 100 Hz, so maybe any excess non-quantum noises around 100 Hz are improving?
   
• (right) Squeezing does not look super optimal right now - definitely would be interesting to do more optimization.. It both looks highly frequency-dependent, and SQZ possibly even lossier now than earlier in ER16, though this is very difficult to say. Recently we've been optimizing SQZ around 350 Hz for range, so it's hard to evaluate high-freq SQZ, since it is misrotated due to the strong frequency-dependence. But even recent ASQZ efficiency could use another look. Maybe we could check OPO temperature, try re-running alignment scripts, etc. General SQZ efficiency is worth some investigations, alongside optimizing PSAMS or SRCL.

Colors: Rainbow colors are ordered past to present: e.g. Red = O4a, ... Purple = now.

Attachment 2 - SQZ dBs after subtracting non-quantum noise, with various recent PSAMS settings. Upper subplot: Anti-SQZ, Lower subplot: SQZ. Lines are a moving average of the data. Some caveats for the subtraction: here I am using the same H1 unsqueezed quantum noise model for all subtractions; this may not be the most accurate, but I think it should be fairly close.

Reference alogs wth times that I used to grab GDS_STRAIN_CLEAN:

• O4a references - 74935 and Gabriele's times from 76825
• 76434 - PSAMS 120/120, March 17
• 76540 - PSAMS 150/90, March 20
        --> corresponding SQZ data set saw ~10-15% higher frequency-dependent losses at 100 Hz vs. kHz unlike earlier Mar16, possibly due to PSAMS settings following 76507
• 76777 - PSAMS 100/100, March 29
• 76798 - PSAMS 125/125, March 29  low-freq glitch in this short SQZ time, difficult to compare. Expect it is similar to 120/120 data?
• 76825 - PSAMS 100/100, March 30  - Gabriele showing total DARM at 100 Hz similar to O4a
• 76872 - PSAMS 100/100, April 2 - opportunistic NO SQZ from last night.