J. Kissel, S. Koehlenbeck, M. Robinson, J. Warner

The LHO install team (Jim, Mitch) -- who has experience installing in-chamber fiber optic systems -- have reviewed the two options put forth by the SPI team for optical fiber routing from some feedthrus to the future location of the SPI follower breadboard on the -X side wall of the HAM3 ISI using Eddie's mock-ups in D2400103. Both options (WHAM-D8 or WHAM-D5) are "evil" in several (but different) ways but we think the lesser of the two is running the fibers from D5 (the currently blank flange underneath the input arm beam tube on the -X side of HAM3; see D1002874).

In support of this path forward, one of the primary evils with D5 is that access to it is *very* crowded with HEPI hydraulics piping, cable trays, and various other stuff. 

Here I post some pictures of the situation.

Images 5645, 5646, 5647, 5648, 5649, 5650, 5651 show various views looking at HAM3 D5.

Images 5652, 5653, 5654 show the HAM2 optical lever (oplev) transceiver, which is a part of the officially defunct HAM Table Oplev system which -- if removed -- would help clear a major access interference point.

Conda packages on the workstations were updated.

There are two bug fixes in this update

foton 4.1.2: magnitude can now be positive when creating a root using the Mag-Q style in the 's' plane.

diaggui 4.1.2: Excitation channel names weren't nested properly on the excitations tab.  This has been fixed.

6.5m off the coast of Vancouver Island. One picket fence station gave us warning before it hit. We were in the process of transitioning to earthquake mode when we lost lock. All ISIs tripped and some suspensions so far.

TITLE: 07/11 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
OUTGOING OPERATOR: Tony
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 3mph Gusts, 2mph 5min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.06 μm/s
QUICK SUMMARY: Locked for 9 hours. Planned calibration and commissioning today from 830-1200PT (1530-1930 UTC).

We're running a patched version of simuLines during the next calibration measurement run. The patch (attached) was provided by Erik to try and get around what we think are awg issues introduce (or exacerbated) by the recent awg server updates (mentioned in LHO:78757).

Operators: there's is nothing special to do. just follow the normal routine as I applied the patch changes in place. Depending on the results of this test, I will either roll them back or work with Vlad to make them permanent (at least for LHO).

TITLE: 07/11 Eve Shift: 2300-0800 UTC (1600-0100 PST), all times posted in UTC
STATE of H1: Observing at 154Mpc
INCOMING OPERATOR: Tony
SHIFT SUMMARY: Observing at 154Mpc and have been Locked for 2.5 hours. The wind looks to be dying down, but I did get a weather warning that the wind is supposed to pick up, so hopefully it's not too bad.

One lockloss during my shift (79012).  When I first started relocking, ALSX was having issues giving high enough flashes, and I was seeing the fuzzy noise in the channel that indicates an issue with the crystal. While this was happening, ALS_XARM wasn't going into the FAULT or CHECK_CRYSTAL_FREQ states, so I just started adjusting ETMX and TMSX and as the flashes got higher, the fuzzy noise and crystal issues stopped.

Relocking took forever because of the high wind and earthquake, but once we finally got past FIND_IR, we were able to go the rest of the way up without issue. There had been a user message on the SQZ PMC guardian at 07/11 01:13 UTC (25 mins after LL) that said, 'PMC_REFL_RF35 demod error', and then kept trying and failing to lock the PMC, resulting in another message: 'Cannot lock PMC. Check SQZ laser power'. I contacted Daniel about this error once we were on our way up to NOMINAL_LOW_NOISE, but all he had to do was re-request the PMC to LOCKED and it unstalled and locked without issue.

LOG:

23:00 Observing and locked for 14.5 hours

00:50 Lockloss
- CPSFF is oscillating and big but peakmon is only at 70 so I'll start an initial alignment
- Some small issues locking ALSX 
    - The flashes were ~0.5 and the fuzzy noise that indicates something wrong with the crystal was happening every few seconds (attachment)
    - ALS_XARM wasn't going to the CHECK_CRYSTAL_FREQ or FAULT states
    - I just aligned ALSX by hand and as flashes got better, it stopped having the bad fuzzy noise
01:26 IA done, relocking
    - Lockloss from FIND_IR x 3
02:20 Took us to down to run a manual initial alignment for INPUT_ALIGN X and Y arms
02:27 Back to DOWN and waiting out earthquake

03:53 Initial alignment
04:29 Started relocking
05:18 NOMINAL_LOW_NOISE
05:21 Observing                                                                                                                                                                        

Just started an initial alignment.

After the lockloss (79012), wind was above 30mph and stayed that high for the next hour, and I believe that might be the reason why while trying to relock in FIND_IR, we would get XARM up but then lose lock before being able to try getting YARM up. In the past we have been able to relock with the winds this high, but I guess not today. While trying to troubleshoot this, we had a large earthquake hit us from the Phillipines (at 02:26 UTC), and just a few minutes ago the ground calmed enough for me to start another initial alignment.

Something strange that may or may not be related to the issues getting through FIND_IR is that after the lockloss and initial alignment, the DCPDs started growing (attachment). This growth in noise seems to turn 'on' and 'off' as the detector was trying to get past FIND_IR.

It's seemed to start increasing again while locking green arms in my current initial alignment.

Lockloss @ 07/11 00:50 UTC from sudden ground motion and also probably the sudden spike in wind.

Ibrahim, Erik, Jeff

The third installation in our new rebuilt BBSS TF saga. See alog 79005 for context.

1. I went to Erik (CDS) to help with fixing the IOP Model Issue and our many errors. His first suggestion was to restart.
2. Erik and I restarted it, broke it in the process (crashing the model and resetting all filter values), then restarted it again.
   1. We had a weird issue where our tripped WD wouldn't untrip despite low values - I think this is still a model issue since it only happened when we turned up the gain on the damping loops (just as a test for the IOP fix)
   2. The DK light is still red but this is due to (almost certain) a different model we're not using having a WD tripped (D1 under the QUAD model).
3. We couldn't untrip the WD so I just left the station for about 30 minutes and tried untripping and it worked! I believe what may be happening is that thresholds are set in different units than the value reading? Definitely some weirdness with the values. Thus, we should check these out once we have what we need TF-wise.
4. I began to take TFs and they actually worked! The coherence looks good and while the values are different when overlaid with our first article Jan 05 ones, they are similar in noise.

Now, since our model and BBSS are both reliably working, Oli and I will take TFs and post them in the next/a new alog.

TITLE: 07/10 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 65Mpc
INCOMING OPERATOR: Oli
SHIFT SUMMARY: Locked for almost 15 hours. Rahul found some good damping settings for ITMY Mode 5 violin and it is damping very nicely. There are a few pending changes that should be loaded on a lock loss or out of observing time.

Pending changes:

    H1LSC model has an unloaded filter which is to due Camilla PRCL FF that she will test tomorrow in the morning.

    lscparams.py has the ITMY mode 5 violin mode updated but needs to be loaded into the guardian

    IMC_LOCK needs a reload to take in notification changes

    OMC DCPD Test bank needs the new anti whitening filters engaged for A1,B1,A2,B2

LOG:

Following TFs on alog 79004, we have been diagnosing the noisy TFs and have come to the simple realization that the DAC is not working and that we were simply not actuating due to a broken IOP Model DAC. All the noise was simply the natural dynamic modes as they were hanging in the clean room. We're getting in contact with the CDS team to fix the issue. Stay tuned.

Oli's Quick partial investigation: Oli plotted multiple channels that the excitation goes through to see if we could narrow down causes (L, T, V, and R). Here are the results with ss of the ndscopes to help compare.

Following up from alog78667 where Sheila compared AS_{A,B,C} powers and some of their ratios during our bad alignments and our good ones, I've done the same thing but at the ISC_LOCK state of Prep_DC_Readout_Transition (500). Just like before, the difference between the lowest good AS_C/AS_A ratio and the highest bad ratio is still pretty low. About the same actually.

TITLE: 07/10 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: 18mph Gusts, 12mph 5min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.05 μm/s
QUICK SUMMARY:

Observing at 150Mpc and have been Locked for 14.5 hours. Winds going up a bit but not too bad.

The following settings seems to be working for now and I will commit it in the lscparams after a couple of IFO lock stretches.

New settings (ITMY05/06):- FM5 FM6 FM7 FM10 Gain +0.01 (new phase -90 degree), might increase the gain later on depending upon how slow the damping is.

Nominal settings (ITMY05/06): FM6 FM8 FM10 Gain +0.02 (phase -30deg)

Given below are settings I tried this morning and it did not work,

1. no phase, 0.01 gain - increase
2. -30 phase, -0.01 gain - increase
3. +30 phase, 0.01 gain - increase
4. -30 phase, 0.01 gain - IY05 decreasing (both filters) IY06 increasing (both filters)
5. -60 phase, 0.01 gain - IY05 decreasing (both filters) IY06 increasing (only in narrow filter)

---

After talking to TJ, I have set the gain to zero on lscparams and saved it but not loaded it since we are OBSERVING. Will load it once there is a target or opportunity.

We cannot make a reasonable assessment of energy deposited in HAM6 when we had the pressure spikes (the spikes themselves are reported in alogs 78346, 78310 and 78323, Sheila's analysis is in alog 78432), or even during regular lock losses.

This is because all of the relevant sensors saturate badly, and the ASC-AS_C is the worst in this respect because of heavy whitening. This happens each and every time the lock is lost. This is our limitation in configuration. I made a temporary change to partly mitigate this in a hope that we might obtain useful knowledge for regular lock losses (but I'm not entirely hopeful), which will be explained later.

Anyway, look at the 1st attachment, which is the trend at around the pressure spike incident at 10W (other spikes were at 60W, so this is the mildest of all). You cannot see the pressure spike because it takes some time for the puffs of gass molecules to reach the pirani.

Important points to take:

• Marker shows when the Fast Shutter was actually fired, which is witnessed by GS13 (bottom left).
• ASC-AS_C cannot be relied on. It started saturating badly even before the FS fired (look at INMONs, 3rd from the top, left), and it kept saturating for a long time.
• OMC QPDs cannot be relied on. They started saturating at about the same time as AS_C though they seem to have stopped saturating earlier  (2nd from the bottom, left).
• AS_B and AS_C cannot be relied on. They're much better than AS_C and OMC QPDs, they started railing some milliseconds earlier than the FS, but they railed (right middle for SUM, one below that for INMONs).
  • But the beam was NOT clipped by the Fast Shutter after it closed as the power dropped to zero, we can see that after WFS stopped saturating.

This is understandable. Look at the second attachment for a very rough power budget and electronics description of all of these sensors. QPDs (AS_C  and OMC QPDs) have 1kOhm raw transimpedance, 0.4:40 whitening that is not switchable on top of two stages of 1:10 that are switchable. WFSs (AS_A and AS_B) have 0.5k transimpedance with a factor of 10 gain that is switchable, and they don't have whitening.

This happens with regular lock losses, and even  with 2W RF lock losses (third attachment), so it's hard to make a good assessment of the power deposited for anything. At the moment, we have to accept that we don't know.

We can use AS_B or AS_A data even though they're railed and make the lower bound of the power, thus energy. That's what I'll do later.

(Added later)

After TJ locked the IFO, we saw strange noise bump ffrom ~20 to ~80 or so Hz. Since nobody had any idea, and since my ASC SUM connection to the PEM rack is an analog connection from the ISC rack that also has the DCPD interface chassis, I ran to the LVEA and disconnected that.

Seems like that wasn't it (it didn't get any better right after the disconnection), but I'm leaving it disconnected for now. I'll connect it back when I can.

Daniel, Nutsinee

I was intrigued by the Twin Sisters Rock feature in the brand new spare SHG Terry and Karmeng put together so I did a little bit of digging. A quick summary is that we believe the Twin Sisters Rock feature were caused by the phase mismatch between the red and the green inside of the SHG cavity. We believe the dichroic coating of the SHG back mirror might be a suspect since the coating specifications can not be found. However, the phase mismatch doesn't neccessary explain the Mount Saint Helens in the 6 year-old SHG we are currently using. 

The equation used to fit the data came from Gonzalez, Nieh, and Steier 1973 equation1. The equation looks similar to the usual sinc^2 function we know and love except that it's taken the phase mismatch between 532 and 1064 and the air dispersion into account in the cos^2 term. This paper also shows that the experimental data doesn't necessary match the model (Fig.3). The problem is we have to related deltaK*l term to temperature. This was done using Kato and Takaoka 2002. This left us with K_0. The only unknown-ish term here is the nonlinear coefficient d_eff inside of K_0. We used d_eff = 10pm/V as suggested by Leonardi et al 2018. After I wasn't able to get a sensible result Daniel pointed out that unit in K_0 doesn't add up. We replaced K0 with equation1 from Arie et al 1997.

The function is also very sensitive to polling length of the crystal. Since we don't have the exact number of the polling length, we picked a polling length such that deltaK is 0 at 34.6 C (optimal phase match condition). The polling length we got was 8.99608um. I believe the crystal polling length according to Raicol is 9um.

The function in the end looks like this. I was able to fit Karmeng's Twin Sisters Rock using sensible parameters (d_eff = 10pm/V, circulated 1064 power of 2W, Boyed-Kleinman focusing parameter = 0.9, and a phase shift of Pi/2). Other variations of the spare SHG plots can be explained by shifting this phi variable.

We suspect the coating of the SHG back mirror might be to blame. None of the SHG plots found in SURF reports (Nathan Zhao, Andre Medina) look symmetric like they should. 

The zip file of the python code is also attached.

If the coating is not to blame, I wonder if it's time we think about redesigning a SHG that is more tolerant to the assembly line errors.

The first attachment shows spectra (GDS CALIB STRAIN clean, so with calibration corrections and jitter cleaning updated and SRCL FF retuned) with OM2 hot vs cold this week, without squeezing injected.  The shot noise is slightly worse with OM2 hot, while the noise from 20-50Hz does seem slightly better with OM2 hot.  This is not as large of a low frequency improvement as was seen in December.  The next attachment shows the same no squeezing times, but with coherences between PRCL and SRCL and CAL DELTAL.  MICH is not plotted since it's coherence was low in both cases.  This suggests that some of the low frequency noise with OM2 cold could be due to PRCL coherence. 

The optical gain is 0.3% worse with OM2 hot than it was cold (3rd attachment), before the OMC swap we saw a 2% decrease in optical gain when heating OM2 in Decmeber 74916 and last July 71087.  This seems to suggest that there has been a change in the OMC mode matching situation since last time we did this test. 

The last attachment shows our sensitivity (GDS CALIB STRAIN CLEAN) with squeezing injected.  The worse range with OM2 hot can largely be attributed to worse squeezing, the time shown here was right after the PSAMs change this morning 78636 which seems to have improved the range to roughly 155Mpc with cleaning; it's possible that more psams tuning would improve the squeezing further. 

Times used for these comparisons (from Camilla):

• no sqz OM2 hot  cold 24/06/2024 12:18:00 UTC
• no sqz OM2 cold hot 24/06/24 23:52:10 UTC
• sqz with psams adjusted OM2 hot 25/06/2024 13:34:52 UTC
• sqz OM2 cold 16/06/2024 11:51:20 UTC