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Reports until 07:52, Friday 05 December 2025
LHO General
thomas.shaffer@LIGO.ORG - posted 07:52, Friday 05 December 2025 (88377)
Ops Day Shift Start

TITLE: 12/0 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None

QUICK SUMMARY: Still in the midst of recovery from the power outage yesterday. Looks like all suspensions stayed damped overnight except the BS which tripped at 0422UTC. SEI is still in a non-nominal state as Jim left it yesterday (alog88373). Many medm screens, scripts, other processes are running *very* slow. 

Recovery will continue, one forward step at a time.

H1 CDS
david.barker@LIGO.ORG - posted 22:36, Thursday 04 December 2025 (88376)
CDS slow filesystem and not all services are back online

Recovery of the front end systems was hampered by a slow /opt/rtcds file system, which still persists. There are no logs on h1fs0 indicating the problem, and the ZFS file system itself appears to be fully functional. Hourly backups by h1fs1 continue normally. At this point we cannot rule out a network issue.

The alarms system is running but does not seem to be operational, again no errors are being logged and channel access appears to be working.

Jim reported a bad model initialization with its safe.snap, most probably caused by a slow /opt/rtcds. I had to restart many models several times to get through a "burt restore" timeout for similar reasons.

We may need to restart h1fs0 in the morning and remount /opt/rtcds on all the NFS clients

Images attached to this report
H1 CDS (SUS)
filiberto.clara@LIGO.ORG - posted 22:01, Thursday 04 December 2025 (88375)
Power Supply Failure for EY SUS-C1/C2 Racks

The positive 18V power supply which provides power to Rack SUS-C1 and SUS-C2 failed after the power outage. Fan seized and power supply tripped off. Power supply was replaced.

New Power Supply  installed - S1300291

F. Clara, M. Pirello

H1 DAQ
filiberto.clara@LIGO.ORG - posted 21:48, Thursday 04 December 2025 (88374)
EtherCAT Corner Station Chassis 4

WP 12915
Corner Station Controls Chassis 4 Wiring Diagram - E1101222
EtherCAT Corner Station Chassis 4 - D1101266
Modifications to the Beckhoff chassis - E2000499

The EtherCAT Corner Station Chassis 4 was modified per E2000499. New Beckhoff terminals were installed to support JAC and BHD. A new rear panel was installed to accommodate the new rear adapter boards and shutter control connectors. The din rail power terminal blocks were relocated making the exising power cables too short. New power cables installed to the EtherCAT couplers and power terminals. All field cabling was reconnected, expect for ISC_313. The Beckhoff software will need to be updated.

EtherCAT Corner Station Chassis 4 - Serial Number S1107450

F. Clara, D. Sigg

H1 SEI (OpsInfo)
jim.warner@LIGO.ORG - posted 20:58, Thursday 04 December 2025 (88373)
Status of SEI recovery

Seems like all of the models are running, but many of the guardians are still down. What I was able to get up and running:

HEPI Pump stations for all 3 buildings. Patrick had to help some with the end station beckhoff. I had to adjust the float switch for the overflow tank at EX, we were ridding just at the trip level there. The corner station Athena looked dead when I powered on the power supply on the mezzanine, but I think some of the leds are just dead. Good thing we plan to replace that soon.

Both BRS are running. Patrick had to power cycle the EX beckhoff, we were then able to restart the software. The damping settings got reverted (highthreshold and lowthreshold), so I had to fix those through the cli. Heater settings also got lost, both brs cooled off a bit over the several hours we were blind, and will take a little while to warm back up. Probably will keep watching for a while to make sure everything is okay, but I think we are good.

Some of the chambers are able to be isolated through guardian, but many have dead guardian nodes. I manually engaged damping where I couldn't get the ISI isolated via guardian.

None of the blend, sensor correction or cps diff is alive enough to recover yet. I have manually disabled sensor correction for the corner, the ends can't be isolated yet.  I guess that will wait for tomorrow. 

H1 SUS (SUS)
rahul.kumar@LIGO.ORG - posted 18:27, Thursday 04 December 2025 - last comment - 18:57, Thursday 04 December 2025(88369)
SUS - power outage recovery

Oli, Ryan S, Rahul

Except ETMX and ETMY (timing error, work currently ongoing), we have recovered all other suspensions by un-tripping the WD and setting it to SAFE for tonight. The inmons looks fine - eyeballed them all (bosems and aosem), nothing out of the order.

For ETMX and ETMY, Dave is currently performing a computer restart, following which they will set to safe as well.

 

Comments related to this report
ryan.short@LIGO.ORG - 18:57, Thursday 04 December 2025 (88371)

Once CDS reboots were finished, I took all suspensions to either ALIGNED or MISALIGNED so that they're damped overnight.

LHO General
corey.gray@LIGO.ORG - posted 18:02, Thursday 04 December 2025 - last comment - 19:20, Thursday 04 December 2025(88350)
Thurs DAY Ops Summary

TITLE: 12/04 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

After CDS & H1-Locking work of yesterday, today we transitioned to starting prep work for the upcoming vent of HAM7.

However, there was more CDS work today which was related to ISC Slow Controls....but in the middle of this...

There was a 90min power outage on site!!
 

LOG:

Images attached to this report
Comments related to this report
oli.patane@LIGO.ORG - 18:36, Thursday 04 December 2025 (88370)

Recovery milestones:
22:02 Power back-up
22:04 CDS / GC seeing what's on/functional, then bring infrastructure back up
22:10 VAC team starts Kebelco to support the ar pressure that's keeping the cornerstation gate valves for closing
22:13 Phones are back
22:17 LHO GC Internet's back
22:25 GC wifi back up, alog and CDS back up
22:40 RyanS, Jason, Patick got PSL beckoff back up
22:55 VAC in LVEA/FCES back up
22:57 CDS back up (only controls)
23:27 PSL computer back
00:14 Safety interlock is back
00:14 HV and ALSY on at EY
00:35 opslogin0 back up
00:37 CS HV back up
00:53 CS HEPI pump station controller back up
01:05 CO2X and CO2Y back up
01:10 HV and ALSY on at EY
01:22 PSL is alive

Note: EY 24MHz oscillator had to be power cycled to resync

Casualties:
- lost ADC on seiH16
- 18V power supply failure at EY in SUS rack

Log:

Start Time System Name Location Lazer_Haz Task Time End
22:32 VAC Gerardo MX, EX, MY, EY n Bringing back VAC computers 23:41
23:32 VAC Jordan LVEA, FCES n Bringing back VAC computers 22:55
22:54 PSL RyanS, Jason LVEA n Turning PSL chiller back on 23:27
23:03 VAC Jordan LVEA n Checking out VAC computer 23:41
23:56 SAF Richard EY n Looking at safety system 00:25
00:02 JAC Jennie JOAT, OpticsLab n Putting components on table 01:24
00:19 SAF TJ EX n Turning on HV and ALSX 00:49
00:38 TCS RyanC LVEA n Turning CO2 lasers back on 01:06
01:03 EE Marc CER n Power cycling io chassis 01:14
01:06 PSL RyanS, Jason LVEA n Checking makeup air for PSL 01:10
01:07 JAC Jennie LVEA n Grabbing parts 01:14
01:08 beckhoff patrick cr - BRSx recovery 02:20
01:08 sei jim EX.EY - HEPI pump station recovery 01:58
01:25 SEI Patrick EX n BRSX troubleshooting 01:54
01:27 EE Marc EX n Looking at RF sources 02:09
02:00 EE Fil EY n Power cycling SUSEY 02:19
02:09 VAC Gerardo MX N Troubleshooting VAC computer 02:27
02:12 EE Marc CER N Checking power supplies 02:16
ryan.short@LIGO.ORG - 19:20, Thursday 04 December 2025 (88372)OpsInfo

Since Oli's alog, I tried to keep a rough outline of the goings-on:

Marc and Fil went down to EY to replace the failed power supply, which brought life back to the EY frondends.

Dave noticed several models across site had timing errors, so he restarted them.

Gerardo continued to torubleshoot VAC computers at the mid-stations.

Once CDS boots were finished, I brought all suspension Guardians to either ALIGNED or MISALIGNED so that they're damped overnight.

I started to recover some of the Guardian nodes that didn't come up initially. When TJ started the Guardian service earlier, it took a very long time, but most of the nodes came up and he put them into good states for the night. The ones that didn't come up (still white on the GRD overview screen) I've been able to revive with a 'guardctrl restart' command, but I can only do a couple at a time or else the process times out. Even this way, the nodes take several minutes to come online. I got through many of the dead nodes, but I did not finish as I am very tired.

Main things still to do for recovery:  (off the top of my head)

  • Finish reviving dead Guardian nodes
  • Maybe restart the main file server (Dave suspects this is the cause of general slowness of CDS machines)
  • Ensure seismic is in a good place
  • Finish Beckhoff software updates that were in-progress at the time of the outage
  • Clear up remaining IPC errors across CDS land
  • Turn lasers back on
  • Check suspension positions
  • Lots of other things probably
  • Thank everyone for their tireless efforts
H1 PSL
jason.oberling@LIGO.ORG - posted 17:41, Thursday 04 December 2025 (88368)
PSL Recovered After Power Outage

R. Short, P. Thomas, J. Oberling

We have recovered the PSL after today's power outage.  Some notes for the future:

I've attached a picture of the Settings table for PSL sensor calibration and operating hours for future reference.  Again, our persistent operating hours (that track total uptime of PSL laser components; OPHRS A in the attached picture) will continue to be wrong as we cannot update this value.  The current operating hours, which tracks operating hours of currently operating components (i.e. we've been running this specific NPRO for X hours; OPHRS in the attached picture) are correct.

We have the PMC and FSS RefCav locked, but have left the ISS OFF overnight while the PMC settles.  The PMC requires a beam alignment tweak (normal after an extended time off, like a 90 minute power outage) but we don't yet have Beckhoff so we don't have access to our picomotor mounts.  I'll tweak the beam alignment tomorrow once Beckhoff has been recovered.

Images attached to this report
H1 SQZ (SQZ)
karmeng.kwan@LIGO.ORG - posted 14:32, Thursday 04 December 2025 (88364)
VOPO crystal mount stage test

[Sheila, Eric, Karmeng]

We checked the NLG of the OPO without cavity lock, threshold power is roughly at 3.7mW, at the same order as the test performed at MIT (E2500270)

Checked the crystal alignment, found 9 good dual resonant position, from -2689um to 1223um, with 490um separation between each point. Everything seems to be in a good position. 

Plus a clipped dual resonance position at -3190um. Crystal edge is roughly at 1500um and -3200um.

Red alignment does not shift between the various crystal position.

LHO General
corey.gray@LIGO.ORG - posted 12:29, Thursday 04 December 2025 (88363)
POWER OUTAGE At LHO At 1225pm PDT!

It's been a few minutes so far.  There is emergency lighting.  Luckily since it was lunchtime there were no people out on the floor.  Recovery Begins!

H1 SEI
ryan.short@LIGO.ORG - posted 11:29, Thursday 04 December 2025 (88362)
Ground Seismometer Mass Position Check - Monthly

FAMIS 38886, last checked in alog88025

Both HAM5 and the BS chambers were in 'ISI_DAMPED_HEPI_OFFLINE' at the time this was run, but all other chambers were nominal.

There are 15 T240 proof masses out of range ( > 0.3 [V] )!
ETMX T240 2 DOF X/U = -1.565 [V]
ETMX T240 2 DOF Y/V = -1.633 [V]
ETMX T240 2 DOF Z/W = -0.886 [V]
ITMX T240 1 DOF X/U = -2.256 [V]
ITMX T240 1 DOF Z/W = 0.467 [V]
ITMX T240 3 DOF X/U = -2.386 [V]
ITMY T240 3 DOF X/U = -1.073 [V]
ITMY T240 3 DOF Z/W = -2.895 [V]
BS T240 1 DOF Y/V = -0.323 [V]
BS T240 2 DOF Z/W = 0.327 [V]
BS T240 3 DOF X/U = -0.547 [V]
BS T240 3 DOF Z/W = -0.401 [V]
HAM8 1 DOF X/U = -0.638 [V]
HAM8 1 DOF Y/V = -0.729 [V]
HAM8 1 DOF Z/W = -1.11 [V]

All other proof masses are within range ( < 0.3 [V] ):
ETMX T240 1 DOF X/U = 0.007 [V]
ETMX T240 1 DOF Y/V = -0.049 [V]
ETMX T240 1 DOF Z/W = -0.017 [V]
ETMX T240 3 DOF X/U = -0.005 [V]
ETMX T240 3 DOF Y/V = -0.056 [V]
ETMX T240 3 DOF Z/W = -0.051 [V]
ETMY T240 1 DOF X/U = 0.045 [V]
ETMY T240 1 DOF Y/V = 0.198 [V]
ETMY T240 1 DOF Z/W = 0.249 [V]
ETMY T240 2 DOF X/U = -0.073 [V]
ETMY T240 2 DOF Y/V = 0.218 [V]
ETMY T240 2 DOF Z/W = 0.037 [V]
ETMY T240 3 DOF X/U = 0.268 [V]
ETMY T240 3 DOF Y/V = 0.076 [V]
ETMY T240 3 DOF Z/W = 0.147 [V]
ITMX T240 1 DOF Y/V = 0.254 [V]
ITMX T240 2 DOF X/U = 0.151 [V]
ITMX T240 2 DOF Y/V = 0.258 [V]
ITMX T240 2 DOF Z/W = 0.223 [V]
ITMX T240 3 DOF Y/V = 0.104 [V]
ITMX T240 3 DOF Z/W = 0.094 [V]
ITMY T240 1 DOF X/U = 0.074 [V]
ITMY T240 1 DOF Y/V = 0.123 [V]
ITMY T240 1 DOF Z/W = -0.013 [V]
ITMY T240 2 DOF X/U = 0.017 [V]
ITMY T240 2 DOF Y/V = 0.22 [V]
ITMY T240 2 DOF Z/W = 0.148 [V]
ITMY T240 3 DOF Y/V = 0.091 [V]
BS T240 1 DOF X/U = 0.184 [V]
BS T240 1 DOF Z/W = -0.223 [V]
BS T240 2 DOF X/U = 0.094 [V]
BS T240 2 DOF Y/V = -0.224 [V]
BS T240 3 DOF Y/V = 0.004 [V]

There are 2 STS proof masses out of range ( > 2.0 [V] )!
STS EY DOF X/U = -4.625 [V]
STS EY DOF Z/W = 2.321 [V]

All other proof masses are within range ( < 2.0 [V] ):
STS A DOF X/U = -0.498 [V]
STS A DOF Y/V = -0.915 [V]
STS A DOF Z/W = -0.485 [V]
STS B DOF X/U = 0.154 [V]
STS B DOF Y/V = 0.939 [V]
STS B DOF Z/W = -0.337 [V]
STS C DOF X/U = -0.685 [V]
STS C DOF Y/V = 0.77 [V]
STS C DOF Z/W = 0.505 [V]
STS EX DOF X/U = -0.195 [V]
STS EX DOF Y/V = -0.111 [V]
STS EX DOF Z/W = 0.112 [V]
STS EY DOF Y/V = 1.271 [V]
STS FC DOF X/U = 0.071 [V]
STS FC DOF Y/V = -1.254 [V]
STS FC DOF Z/W = 0.567 [V]
 

H1 CAL
elenna.capote@LIGO.ORG - posted 10:43, Thursday 04 December 2025 - last comment - 14:46, Thursday 04 December 2025(88361)
Calibration measurement post DAC swap

Last night I took a calibration measurement (broadband and simulines) after the IFO was locked for about 3.5 hours. This generated calibration report 20251204T035347Z.

The results from broadband and simulines on the front page look reasonable. The plot label indicates that these are from PCAL X and Y but I think the broadband and simulines are run on PCAL Y only, so I don't know if PCAL X agrees with Y. I believe as of last night, the DAC for PCAL X had been swapped.

I made no changes to the pydarm ini file to account for the DAC change before running the report.

Non-image files attached to this report
Comments related to this report
elenna.capote@LIGO.ORG - 14:46, Thursday 04 December 2025 (88365)

Jeff and I looked over the report and have concluded that the changes we see are very minimal, and do not require any updates to the calibration at this time.

There is a 1% change in the L3 actuation strength, comparing the measurement from 11/18 and 12/04. This could be from the DAC change or it could be from charging. Either way, it is small enough that kappa TST is likely correcting this properly. The overall systematic error is still around 1%, as it was before the DAC change.

We don't think there needs to be any changes to the pydarm ini file at this time.

LHO VE
david.barker@LIGO.ORG - posted 10:36, Thursday 04 December 2025 (88360)
Thu CP1 Fill

Thu Dec 04 10:15:45 2025 INFO: Fill completed in 15min 42secs

Plot has zoomed y-scale to reduce number of divisions in order to show detail.

Images attached to this report
H1 PSL
ryan.short@LIGO.ORG - posted 10:25, Thursday 04 December 2025 (88359)
PSL Cooling Water pH Test - Monthly

FAMIS 27645

pH of PSL chiller water was measured to be between 10.0 and 10.5 according to the color of the test strip.

LHO General
corey.gray@LIGO.ORG - posted 07:43, Thursday 04 December 2025 - last comment - 09:47, Thursday 04 December 2025(88351)
Thurs DAY Ops Transition

TITLE: 12/04 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 3mph Gusts, 1mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.33 μm/s 
QUICK SUMMARY:

H1 has been locked almost 15hrs....but H1 is going DOWN in prep for the HAM7 vent and will be set to IDLE. 

There will be more CDS (have heard Beckhoff) work, but no "proof of life" for H1 after that work will be done. 

Now the focus is on prep to vent with Kim & Nellie commencing shortly with thorough technical cleaning of HAM chambers.  Other possible items on the list for today:  

Comments related to this report
corey.gray@LIGO.ORG - 09:47, Thursday 04 December 2025 (88357)CAL

FYI:  Elenna ran a Calibration last night (she noted in Mattermost and files were generated at 818pmPDT).

H1 ISC
sheila.dwyer@LIGO.ORG - posted 23:01, Wednesday 03 December 2025 - last comment - 10:24, Thursday 04 December 2025(88348)
instructions for recovering alignment after gate valves are excercised

It seems like it would be useful to have this recipie written in one place.  After the gate valves are opened and closed, we often have a hard time relocking because of alignment.  

Here's what we think we should do to recover after gate valves open.  

  1. Do initial alignment without using green cameras in the loop, as the cameras are right next to the gate valves. 
    1. Start by using the baffle PD dither alignment script to set the TMS alignment: use the suspension guardians to misalign both ITMs and ETMs, run dither align script for both TMSs found on the INIT ALIGN MEDM, (dither align scripts, TMSX and TMSY, can run at the same time).  Open the ITM baffle PD scope and watch the script find the pointing of TMS that sets the beam to PD1, PD4, and finally centered on the optic.  When this finishes sucsesfully for both TMSs, there should be a dim green beam visible on both ALS cameras, if there is not check the alignment of PR3 (affects both arms) and the BS (only moves the Y arm beam).  This TMS alignment has to be set before you can move onto the next step, otherwise the ITM alignment won't be right. 
    2. Use the suspension guardians to align both ITMs, but leave the ETMs misaligned.  Run the dither alignment script for ITMX and ITMY, this time watching the ETM baffle PD scope to watch the script's progress.  Once this is finished, the ITMs should be set, and we should not move them based on the cameras. 
    3. Use the suspension guardians to set the ETMs to aligned, and you will hopefully see mulitple beams or cavity flashes on the ALS cameras.  You can manually align the ETMs to increase the flashes until they are good enough to lock the arm.  Use the ALS guardians (in auto mode might be helpful) to set them to ETM_TMS_WFS_OFFLOADED, this will not run the green camera servos, it runs green WFS to the ETM and TMS alignment only to increase build up. Don't run INITIAL_ALIGNMENT or INITIAL_ALIGNMENT offloaded. 
    4. Align the vertex to these ITMs: set the ALIGN_IFO guardian to manual, init it to control the suspension guardians.  Choose INPUT_ALIGN_OFFLOADED, once that finishes PRC_ALIGN_OFFLOADED, then MICH_BRIGHT_OFFLOADED, then SRC_ALIGN_OFFLOADED.  
  2. Make two guardian changes before you start locking the full IFO
    1. Don't use the SRC1 + SRC2 ASC loops in DRMI, these don't seem to work until the alignment is set well for full lock.  You can turn these off by going to lscparams, and searching for use_DRMI_ASC, setting SRC1+ SRC2 to false.  Load ISC_DRMI for this change to take effect. 
    2. Don't shutter the ALS beams once they are no longer used for locking.  In ISC_LOCK, find the edge     ('IDLE_ALS',  'CARM_OFFSET_REDUCTION', 5), and reduce the weight which is normally 5 to 1, so that this path which avoids shuttering the ALS becomes the default path.  Load ISC_LOCK for this change to take effect.
  3. Start to relock as usual, going through PRMI.  Stop at CHECK_DRMI_ASC, where all the DRMI ASC loops will be running other than SRC1+SRC2, and manually adjust SRM sliders to reduce POP90 and increase POP18. 
  4. You can try to lock all the way to ENGAGE_ASC for full IFO, but this may not work.  If it does not, you may need to manually align DHARD, CHARD, and SRM. 
    1. If you are adjsuting alignments by hand, you want to keep the green beams locked to the arms as the alignment changes.  To get the green alignment to follow any changes you make, stop at IDLE_ALS and turn on the scripts that servo the green TMS QPD offsets based on the green WFS.  You can access this script by going to either ALS end station overview and clicking the button that says QPD OFFSETs, then using the pink drop down button to start the servo for each arm, and open the ndscope that lets you watch the progress of these servos (screenshot)
    2. If the power in the two arms is mismatched (visible on the PRMI SB4 min ndscope on the front wall), this could be a sign that DHARD is misaligned. 
      1. If you notice this in a state before DHARD WFS are closed, RF_DARM or CARM_OFFSET reduction , you can use the move_arm_dev script to step DHARD pitch and yaw to bring the arms closer to each other.  userapps/asc/h1/scripts/move_arm_dev.py DH P 0.01, or similar.  
      2. If you notice the arm powers diverging from each other after DHARD WFS are closed, this might be fixed by moving SRM while watching to make sure POP 90 stays low.  
    3. If the power recycling gain is low, you may need to adjust CHARD.  You can step through CARM_OFFSET reduction or stop after it finishes and use 62110 to check if the refl power is too low for the arm transmission that you are at, and try to move CHARD while trying to increase the refl power (watch build_up_slow ndscope linked from the ISC guardians overview and other places).  
  5. Once you are all the way locked (congratulations), stop at PREP_ASC_FOR_FULL_IFO before you try turning on ASC.  It may be a good idea to note the green QPD offsets with a screenshot, if you loose lock they wil be reverted with SDF revert but you would need to reset them to these values to relock.   Also look at the ITM green camera offsets, from each ALS end station overview in the green WFS section there is a button that says CAM ITM YAW or PIT, you can take a screenshot of this screen for both ITM cameras and compare the current location of the beam centroid to the setting (screenshot)
  6. Use a guardian shell (guardian -i ISC_LOCK) to copy and paste lines from ENGAGE_ASC_FOR_FULL_IFO manually, skipping SRC1 +SRC2.  (you might grab another screenshot of the green QPDs and cameras at this point)
  7. Then you can manual the guardian to TMS_SERVO, engage_soft_loops, and DARM offset, and take another green QPD offset + camera screenshot.  
  8. Having the DARM offset on as well as the soft loops seems to help the SRC ASC work, so try engaging those once those steps are done.  (Congratulations on getting all the ASC controlled)
  9. Important step: reset the green references.  In the past we have reset the green QPD offsets by accepting them in SDF as well as the camera offsets, but it doesn't make sense to be changing the QPD offsets as they shouldn't be impacted by the gate valve moving the camera.  Today once we had all the ASC engaged, we stepped the QPD offsets back to their original settings from SDF, watching the arm transmissions in the ndscope.  The arm transmissions seemed fine with the original QPD offsets, so we left those there and only updated the green camera offsets.  I think this should be the way we do things in the future, not reseting the QPD offsets by default.  
  10. undo the gaurdian changes from step 2 above.  After the next lockloss, run initial alignment as usual, letting the green cameras be used to point the ITMs.  DRMI ASC should work now that the alignment has been set.  

 

Images attached to this report
Comments related to this report
elenna.capote@LIGO.ORG - 10:24, Thursday 04 December 2025 (88358)

Thank you Sheila for writing up this process in very helpful detail.

I wanted to add a few more notes based on many iterations of this process.

#2 and 3 add on: often, if the vent was invasive enough, the other DRMI loops besides SRC ASC may also give some trouble. There are options in the use_DRMI_ASC and use_PRMI_ASC to also disengage PRC1 (PRMI and DRMI), INP1 (DRMI), PRC2 (DRMI) and MICH (PRMI and DRMI). I recommend disengaging PRC1, INP1 and PRC2 if the DRMI ASC is not working well and PRC1 for the PRMI ASC. This will then require moving PRM (PRC1), PR2 (PRC2) and INP1 (IM4) by hand. We rarely disengage MICH. Generally MICH needs to stay on during CARM offset reduction so the beamsplitter can follow DHARD. Also note that SRC2 controls both SRM and SR2, so SR2 may need to be moved as well as SRM.

#4 add on: the DHARD error signal may be very bad if the arms are too far away from resonance, and the error signals can flip sign as the CARM offset is reduced. To make DHARD engagement easier, it might be helpful to step the CARM offset by hand while moving DHARD manually, even taking smaller steps than the guardian code does. Then, DHARD can be engaged. Note: if you find yourself flipping the sign of the DHARD loops to engage them, this is a problem, and you will likely have a lockloss during CARM offset reduction if the DHARD loops are closed with the wrong sign!

#6 and 7 add on: if the alignment is poor enough, it might be necessary to walk the IFO alignment further before engaging the loops in ENGAGE_ASC_FOR_FULL_IFO by putting the guardian code in the terminal. This is the process I follow:

  • group the loops into CHARD/INP1/PRC2 pitch and yaw
  • turn off the soft limiters so you can see the full error signal
    • I find the full IFO ASC ndscope template useful here: sitemap>LSC>locking>locking scopes>ASC signals
    • sitemap>ASC>overview>ASC arm cavities/central part> upper left corner of each loop control block called "[loop]_SMOOTH_ENABLE"
  • step CHARD using the move_arms_dev.py script, PRC2 with PR2 slider and INP1 with IM4 slider. Start with either pitch or yaw only. These loops are sometimes cross coupled, so you might need to step one and then the other iteratively. Check that as the error signals go to zero the buildups improve (PRG, POP18 and arm power increase, POP90 decrease)
  • Once the error signals are close to or at zero, use the guardian code to engage their filters and gains to close the loop. Repeat this process for pitch and yaw.
  • Before closing ADS3, move PRM to bring the ADS error signal close to zero
  • Then, proceed to move SRM and SR2 to close SRC1 and SRC2. If this doesn't work, leave them open until the soft loops are closed, then try again
  • You might need to go line by line with the guardian shell for ENGAGE_SOFT_LOOPS. ADS4 and ADS5 control the X arm SOFT and Y arm SOFT dofs respectively. You can also use move_arms_dev.py to steps these dofs closer to zero before closing the loop

I like the recommendation of noting the green camera references throughout the process. If you lose lock before you get a chance to reset the references, you will have to repeat the whole process (alignment does not offload after DRMI!). Jenne's metaphor is that the green references are like video game save points, so noting them throughout the process can be helpful in case a lockloss happens, you can return to where you were before. The final green reference setting should be after all alignment loops are closed (including soft loops!).

Another offset that is useful to reset is the POP A offset. In DRMI, PRC1 runs on the POP A QPD and the alignment is offloaded. If the POP A offsets are set to the PRM's final location in ENGAGE_ASC_FOR_FULL_IFO, the ADS convergence for DOF3 will be much faster, as DRMI will put the PRM where it already needs to be. The convergence of this loops is so slow it sets how long this state takes, which can be many minutes if the PRM is far off from where it needs to be.

thomas.shaffer@LIGO.ORG - 08:29, Thursday 04 December 2025 (88353)OpsInfo

Created a wiki page for Recovering the IFO After Gate Valve Closures and added a link to that wiki in our ops Troubleshooting the IFO wiki. This way we can make changes next time we exercise this procedure and hopefully it leaves more bread crumbs to find it again.

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