The LVEA has been swept, I unplugged an extension cords that were not connected to anything, and the genie lift near the west bay.
The test system for 4k Ethernet was moved from EY to EX, ending the test at EY.
The link was tested between the MSR and EX at 100G for a short itme. The link tested at 80G, the maximum the software can test.
The link is now being tested long-term at 25G. So far, no issues.
Earlier log entry about test at EY https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=87811
I inspected the PSL chiller lines external to the PSL enclosure this morning and found no issues or anomalies. This closes FAMIS 27545.
[Jenne, TJ, Elenna]
The last three locks saw a violin mode ring up (see 87933), which managed to saturate the DCPDs and cause a large amount of excess noise, see this screenshot of DARM near the time of lockloss. I am assuming that all of the extra noise is a result of some crazy nonlinearity due to the saturation DCPDs.
Jenne and I have concluded that the mode that rung up must be ETMX mode 1, which the violin mode monitor screen reports is at f = 511.2993 Hz. However, we have looked at GDS calib strain when the mode has rung up using both diaggui_test and with exported data in python at double precision with fft length of 4096 and 1024 seconds respectively and find that the mode is at 511.269 Hz, DTT screenshot, matplotlib screenshot.
Jenne has plotted both the damping filter and the monitor filters here. We can see that the damping filter is broad enough to cover this frequency, but the monitor filter is not. The violin mode guardian is supposed to track the modes via the monitor filters and disengage damping if the mode is ringing up. However, we think the monitor filter might be missing this frequency and this is why the damping did not turn off.
The attached timeseries also shows that the DCPDs were railed for some time, the suspension drive on ETMX L2 was very nearly saturated, and the monitor filter level was low overall, near 3.5. Jenne has included channel H1:FEC-88_ACCUM_OVERFLOW, maybe this is a useful channel for us to monitor.
I just want to add that I am being specific about how we measured the mode frequency above because we have been confused by insufficient precision before. I think we have sufficient precision to measure this frequency accurately, but the results show a shift of 0.02 Hz from the previously reported value.
Here is a follow up on the mode frequency that is very confusing! The ETMX mode 1 and mode 6 damping was disengaged about 20 minutes before our last lockloss. If I plot the strain spectrum in the 20 minutes before the damping was off and then the 20 minutes after, I see the expected ETMX mode 1 and 6 peaks at 511.18 Hz and 511.2993 Hz Hz. Only in the spectrum with the damping on do I see a large peak at 511.27 Hz. Jenne and I don't understand that yet, but are thinking about it. Plotted in diaggui_test with fft length 512 seconds, 2 averages with 50% overlap in each measurement.
The attached plot shows ETMX mode 1 and 6 damping ON in red and ETMX mode 1 and 6 damping OFF in blue.
However, the mode 1 filter is more likely to be the culprit, since it actually covers 511.27 Hz whereas the mode 6 filter does not, filter screenshot.
And, here is a version of the spectrum over time. Probably the 'true' ETMX mode 1 is the one closer to 511.3 Hz, which is consistent with the filters as well as Rahul's violin mode identification spreadsheet, and the 511.269 Hz that we've had trouble with today is something else that is outside the width of the monitor filter, but inside the width of the damping filter. As Elenna's alog shows, it's not really clear what the filters are picking up to drive at 511.269 Hz, but probably the damping filter was set up for 511.3 Hz and so when being applied to something at 511.269 Hz it just feeds nonsense.
In the attachment, I show strain spectra from 3 different times when the alog has mentioned violin modes at around 511 Hz. Green is today (after we were saturating, hence the elevated background), brown is this Oct 2025, and pink is Aug 2023. All of the times have a small peak at 511.302 Hz (which is not so far from the ETMX mode1 monitor and damping filter central frequecy of 511.299 Hz), so that's probably the true violin mode. Oct and Nov have also this much larger peak at 511.269 Hz, which is this new confusing peak. I haven't looked at any times other than these 3, so it's possible that the 511.269 Hz has come and gone before Oct 2025.
Also shown is the ETMX mode 1 monitor and damping filters, showing that as Elenna said the monitor filter seems to only catch the 'true' mode, while the damping filter is broad enough for both of these frequencies.
I had to do this check a week ago, but no damage was observed at either end.
Closes FAMIS 27396. Last checked in alog 87787
Plots look fine compared to last week but BSC High-Freq noise is elevated for these sensors:
ITMX_ST1_CPSINF_H1
ITMX_ST1_CPSINF_V1
ITMX_ST2_CPSINF_V1
Note - it is Tues Maint. so there are people in the LVEA.
There was a 7.5Hz peak in TJ's last-week check that is now gone. It was most prominent in HAM1 it seems.
Pdf Attached.
Tue Nov 04 10:05:35 2025 INFO: Fill completed in 5min 31secs
Gerardo confirmed a good fill curbside.
Randy and I installed new CR ceiling.
Betsy had a local company fabricate a C3 ceiling for our Mega Cleanroom. This ceiling has velcro opening to allow access for Septum removal. Opening extends to end of CR opening on the -X side and ends just short of the +X opening.
I've removed the Misaligned states and their associated edges for the IMs and MC1 nodes to avoid a similar mishap from last week (alog87793) of going up to 60W but misaliging optics that should not be moved at that power.
To do this I needed to make h1 versions of these nodes. Most other sus nodes are common, and these do use the common SUS.py file, but we redefine the edges and removed the misaligned and misaligning states.
Sheila, TJ
We also added the OMs, OPO, and OFI to the list. This brings the total list of sus nodes without misaligned states to:
The quarterly maintenance of Chiller 3 and pump at the Corner Station has been done. Additionally, all chillers site-wide have been rotated.
TITLE: 11/04 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Lock Acquisition
OUTGOING OPERATOR: Oli
CURRENT ENVIRONMENT:
SEI_ENV state: CALM
Wind: 8mph Gusts, 5mph 3min avg
Primary useism: 0.02 μm/s
Secondary useism: 0.29 μm/s
QUICK SUMMARY: Violin modes are very rung up, although our violin monitors dont agree with that. Our range has been very low for the past 2 hours, as if the squeezer isn't squeezing. While the magnetic injections are running right now, I don't think they are getting anything useful. Still trying to figure out what's going on.
Maintenance day today.
Looks like this happened to Ryan C last night as well - alog87930. I did just as he did and turned off the damping to violin ETMX modes 1&6, and the saturations went away and DARM looked better. The 500Hz line in DARM is still very elevated, but the harmonics are much lower and the DCPDs are no longer saturating.
Now that the gains are off, the monitors are making more sense for those modes. They immediately went up when the gain was turned off.
SUS in lock charge is running and should be good, at least for the latter half of the measurements.
I've set the gain of ETMX mode 1 to zero in lscparams for now.
Workstations were updated. This was an OS packages update. Conda packages were not updated.
TITLE: 11/04 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Aligning
INCOMING OPERATOR: Oli
SHIFT SUMMARY: One lockloss, we are relocking at MAX_POWER.
LOG:
| Start Time | System | Name | Location | Lazer_Haz | Task | Time End |
|---|---|---|---|---|---|---|
| 23:50 | CAL | Tony | PCAL lab | LOCAL | Prep for end station meas tomorrow | 00:35 |
| 00:49 | CAL | Rick | Receiving | N | Pick up PSL parts | 01:25 |
| 00:52 | OPS | Ryan | Optics lab | N | Check on dust monitor | 00:58 |
03:45 UTC Something started to ring up in the DCPDs and the 500Hz line looked large on DARM. None of the vioins were ringing up though, I eventually found that both ETMY and ETMX (mostly ETMX) mode1/6's drive was ringing up and once I turned off the damping the DCPDs came back down and so did the line on DARM. (tagging SUS). I then put the nominal gain back into ETMX mode6 and it started to damp back down.
04:03 UTC We dropped observing, I brought us to Hi gain ASC as a semi large earthquake from Eastern Russia was hitting us (6.0)
04:19 UTC lockloss from the Earthquake
04:55 UTC MC2 M3 tripped as the IMC was trying to relock after a lockloss from FIND_IR, a look at some of the OSEMs
04:56 UTC IA, after INPUT_ALIGN it took the IMC 6 minutes to relock itself
SEI_ENV went to high gain ASC state on its own here for 15 minutes before we lost lock.
04:19 UTC lockloss from a 6.0 from Eastern Russia, we were in the Hi gain ASC state at the time trying to ride it out.
M. Todd
I ran ISS injections in several bands during commissioning today (1-20 Hz) until about 9:30 PT. I am still struggling to get coherence below about 4 Hz, but the measurements of the transfer functions match relatively well with models of the ISS couplings to different ports in the IFO, except for POP. This could be sideband dominated dynamics, but more thought is needed.
After ~1 week, no long RTTs, and no NIC reported error counters of any type (Attached is one sides output).