S. Muusse, G. Bolingbroke, C. Compton

The new QCL laser 0922 was installed in the setup to replace the broken 0920 unit and has been turned on and its working. Thermal paste got on the output lens during storage/transport and but we cleaned off using tissue and isopropanol. The main path alignment has been completed but the pickoff paths havent been checked and lenses havent been replaced. The new unit requires a slightly different lens position described in the yaml file which will hopefully be installed tomorrow. 

After opening the X arm,  Jenne used the baffle PD script to roughly align the X arm.

We've found that the green beam was too high, hitting the aluminum part of the top periscope mirror mount. But it was off in YAW, too. We moved the PR3 to see what happens, but we ended up reverting it and moved pico steering mirror for POP path in HAM3.

In PIT, green beam was brought to a place where it's higher than the middle of the top periscope mirror because centering that beam in PIT the IR beam will be clipped.

The IR beam was still very close to the +X-Y edge of the dichroic and also the 90:10 to split in-air and in-vac beams, so pico-ed in YAW too.

At this point there was a HUGE pit offset on POP-X, the beam was hitting the top of the QPD case, and large (but not huge) yaw offset. We couldn't center the beam using PM1, so we used the dichroic.

We had to set the DC gain of the WFS DC interface on the front panel to HIGH to be able to see any meaningful DC signal from POPX, but anyway we managed to roughly center the beam in that H1:ASC-POP_X_DC_PIT_OUT and H1:ASC-POP_X_DC_YAW_OUT go both positive and negative as the beam fluctuates.

We didn't see anything on LSC POP_A at this point. We scanned PM1 and found that the beam is not that far and off mostly in PIT. We used a pico-ed splitter to split ASC and LSC POP to steer the beam on POP_A. We scanned the PICO to roughly put the beam at the center of the plateau. I say "roughly" because we used PRX beam which was freely flashing, so it was hard to go precise, but we can always do it after pumping down.

I say that the in-vac alignment is done (in that we can fine-tune after pumping down using picos and suspensions in HAM1 and also using pico in HAM3 if necessary).

Since we changed the HAM3 pico and made a large adjustment of the dichroic, the in-air POP beam as well as the green beam should have been affected. We'll put the table by HAM1 and see how they land on the periscope, and will adjust the steering mirrors in HAM1 if needed.

To test out new infrastructure for running IOCs and other services in CDS I put the MX weather station into a podman container and started it on our new service-host cluster (a high availbility cluster for services).

As part of this I created a generic container that should work for the other weather stations and the dust monitors (until those are migrated to beckhoff).

This work is part of an effort to improve our infrastructure, including how we track, monitor, and manage our IOCs.  There should not be any user visible change with this, other than the IP address that the IOC responds from is different.

Notes:

 * We run these older IOCs in the background with screen as they are iocsh shells and want a terminal.  For this setup I no longer need to run with screen, we just tell the container system (podman) to run the container with a tty in interactive mode in the background.

[Georgia B, Elenna, Oli]

Last Friday I reported that the alignment to OMCA was decent, 89674. However, I had aligned OMCA with an HR and then removed it to align OMCB. On Monday, I tried placing a beamsplitter at the same location so I could simultaneously align OMCA and OMCB, but then I didn't have enough power for both. I then tried to fix the upstream fiber, which at first went horribly, but now we are getting 50 mW to align with, so overall things have improved.

Today, Oli and I began to realign the beams to the OMCs, since so much changed upstream. Georgia then later tagged in to help me. For alignment, we have about 33 mW to align OMCB and about 17 mW to align OMCA. This enough to see flashes on the card at the DCPDs.

Summary: we see flashes at the DCPDs of OMCA and OMCB. These flashes look pretty good overall. The beam is not modematched to the OMCs, so the flashes look mostly like mode mismatch.

We used the IR sensitive camera to take long exposure shots of the DCPDs to capture a long average of the flashes.

Here is a picture of both DCPDs of OMCA. There are some blobs that indicate the alignment could be a bit better, but overall it looks pretty good.

Here is a picture of DCPDA of OMCB. This mostly looks like mode mismatch, so again, decent alignment overall.

I have also attached videes of the OMCs flashes on an IR card.

TITLE: 04/01 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

HAM1 & SQZ alignment work continued with focus on HAM1  GV7 was opened for a check down the X-arm for HAM1 work.  Team is still out at HAM1 and GV7 will be open overnight.  Would like to have ISCT1 rolled into place in the morning.

LOG:

• 1406- lvea technical cleaning (nellie.kim)
  • 1526 nellie out
  • 1600-1634 MY technical cleaning (nellie)
• 1420-1520 craning handrails up to the eMod (randy)
  • 1550-1740 clean-up in lvea
• 1511-1645 HEPA Fan swap at h1psl (tyler,eric)
  • 1645-1655 Move to optics lab for termites? (tyler)
• 1529-1657 SPI in optics lab (sina)
  • 1626-1657 SPI in optics lab...but only for about 30min before a meeting (jeffK)
  • restart after meeting - 1915 More SPI before lunch (sina, jeff)
• 1614-1638 lvea walkabout around h1psl (richard)
• 1702-1708 turning off mega cleanroom fans (richard)
• 1703-1717 Opening lightpipe & HAM1 door cloth cover for alignment work (sheila)
• 1706-1714 checking h1psl hvac (post new fan install) [jason]
• 1725-1731 Turning down HAM1 purge (keita)
• 1728 cheta lab (sophie,georgia)
• 1745-1905 susR2 rack near HAM3 + upstairs of CER (fil)
  • 2000-2320 Continue rack & CER work (fil)
• 1757 OPEN GV7 (gerardo.travis)
  • 1808 jordan joining
  • 1825 GV7 OPENED
• 1940-2038 Cleanroom lowering a few inches in West Bay (randy,eric,tyler,mitchell)
• 1953-2148 BHSS laser HAZARD work (elenna,oli)
  • 2049 Oli out
• 1959 Checking green beam at HAM1 (keita)
  • 2013 jenne & sheila joining
  • 2249 Jenne out
  • 2259 sheila out---
• 2007-2148 CHeTA laser set-up (sophie, georgia)
  • 2022-2142 Camilla joining
• 2013 MX weather station work (jonathan)
• 2018 checking on cleanroom team (richard)
• 2053 SPI assy & alignment (jeff, sina)
• 2054-2113 RGA search (gerardo)
• 2104-2110  Running cleanroom roof sock to lvea (randy)
• 2118-2122 fiber feedthru check at HAM7 (travis)
• 2120-2143 EX cleanroom accessory search (randy)
• 2130 PM1 @HAM1 had software WD tripped noticed, and he is bypassing (since there is lots of shaking out there) [dave]
• 2143-2200 Going to PCal Lab for dustmonitors (ryanC)
  • 2226 now going to swap out a cable--heading to CER & then back to PCal lab (ryanC)
• 2155 Betsy & Camilla joining HAM1 team on the floor
• 2216-2316 BHSS alighnment (elenna,georgia)
• 2236 Artemis launch!
• 2256 M7.8 EQ in the south Pacific with S&P waves hitting at 2300 (R-waves due around 2350-0000)
• 2302 Checking on HAM1 team (richard)
• 2307 CHeTA laser HAZARD work (sophie)

Sina, Jeff

The photodetector chassis of the LIGO-SPI pathfinder has been modified to maximize the CDS range. The TIA is designed to put out 0V - 10V on the positive leg of the differential output. The power monitoring PDs are set to get close to 5V, the interferometer PDs a mean of 2.5V, and the QPD quadrants 3.5V each. The whitening filters for the heterodyne-interferometer photodiodes are bypassed. The details of the installed capacitor and resistors are listed in the following table:

The capacitor for the QPDs might be changed to result in a low-pass frequency of 10 kHz at a later date.

Sina, Jim

We tested the functioning of the picomotors in the LIGO-SPI Pathfinder ISIK and ISIJ assemblies. All motors are working (see attached video).

After the vacuum team opened up GV7 so that we can have a peek down the arm, I ran the green baffle PD scripts for the Xarm.

I did the usual misalign ITMX and ETMX, and ran the script for TMSX.  I then realigned ITMX, and ran the script for ITMX.  I then realigned ETMX and ran the script for ETMX.  

I looked at H1:ALS-X_REFL_A_DC_POWER and moved ETMX a bit to try to get some refl dips, which indicate that there are some flashes in the Xarm.  ETMX is not at all optimized, and I haven't touched TMSX since running the baffle align script on it. 

The baffle align script moved ITMX 5 or 6 urad "down" in yaw, and very little in pitch.  The attached screenshots shows times before, during, and after the baffle align script, for the ITMX sliders, top mass osems, and oplev.  The only difference between screenshots is whether cursors are included for convenience.

Sheila,  Camilla 

Yesterday, Sheila moved ZM3 in steps of +10urad in PIT on the sliders (towards the diorection we know we need to be for SQZT7 light). She then compensated with FC1 and FC2 to maximize FC green flashes each time. And then measured the amount ZM3 needed to be moved to get light on SQZT7, ZM3 needed to be moved less each time to get light on SQZT7 IR PD (good) however, the flashes could not be brought back to thier maximum (bad). Plot attached.

Today, I moved ZM3 in steps of -10urad in PIT on the sliders (away from the diorection we know we need to be for SQZT7 light). Then compensated with FC1 and FC2 to maximize FC green flashes each time. And then measured the amount ZM3 needed to be moved to get light on SQZT7, ZM3 needed to be moved slightly more each time to get light on SQZT7 IR PD (bad), but the flashes could be brought back to thier maximum and mayeb even got slighly better (good). Plot attached

For the HAM1 work today, here are two screenshots showing PRX alignments with two different PR3 values.  

PR3 yaw slider at -233.7 urad is here, since HAM2 HEPI is locked 3.7 urad positive RY compared to it's usual location (89701), this corresponds to -230 urad our yaw alignment from O4 (and from the March 14th PRMI/DRMI locking).  

PR3 yaw slider at -240, here, is the alignment for which in the in chamber crew found the beam on the edge of the ASC POP X diode.  

[Keita, Oli, Jenne]

To make relocking the IMC easier during the HAM1 work, JM3's damping has been significantly increased.  Oli did mention that the JM3 damping loops haven't seen much real tuning yet, so even when we discontinue this overdamping, we may want to spend some time on them.

Attached are screenshots of JM3's damping loops before we tuned anything, as well as how we're leaving JM3 overdamping for now. 

The spectra show JM3 damping, but with gains of -2 in each of the Pit and Yaw loops as the references (so, a little more damped than they were yesterday), and then the live traces are with the overdamped situation.  

As a comparison, Oli pointed me to this old alog 62672 with a similar suspension's damping loops measured. 

Wed Apr 01 10:14:14 2026 INFO: Fill completed in 14min 11secs

On Monday I had a good alignment for the FC, see 89694  and that alog's attached screenshot. Yesterday we went there and had to touch up FCs a little to get flashes. Today for the same sliders was even worse witha very PIT misalinged FC Green beam, see attached, in the same FC1 PIT slider potion, the osems were 150urad off, attached. When I brought us back to the top mass osem positions for all optics (ZM1,2,3,FC1,2 and ZM2 PSAMS) we have no green flashes in the FC, just a single pass green beam, attached. 

1.  Why is the FC1 top mass osems drifting 150urd in 24 hours
2.  We don't seem to be able to trust the osems as going back to them gives us no FC flashes.

Rahul did in-air TF's 75830

For FAMIS #39861: Fans look mostly flat (Corner's FAN5 looks faintly noisier the last 1.5 days).

(Jordan V., Travis S., Gerardo M.)

We removed and replaced the broken pressure regulator for GV7, we haven't tested the new regulator yet (open or try to hard close GV7), but hope to do so soon. During the regulator replacement we installed an isolation valve on the line that feeds GV7, this for upcoming work on this system.
While doing the replacement of the regulator for GV7, we discovered that the pressure regulator for GV8 pneumatic system is broken too, currently it is reporting a max pressure of 100 psi and a low pressure of 80 psi, it rides the instrument air compressor behavior (high and lows).  We tried to lower the pressure but the regulator is non-responsive.  We'll replace the pressure regulator at the next opportunity.  Also, it turns out that the pressure regulators attached to the different pneumatic gate valves are not the same model.

Sheila, Keita, Jennie W, Jenne D, Georgia B.

We want to be able to power up to 20W in JAC to check the POP beam.  

We were loosing lock with about 8W into JAC because the REFL shutter was closing.  Jennie Wright measured 6mW on the REFL diode with 2W input to HAM1 and JAC unlocked yesterday.  This corresponds to 0.58V on the shutter trigger diode.  The threshold cannot be set above 2V, which means we would unlock when 21mW hit the diode.  Jennie Wright added a ND05A into the path before the refl diode, and another ND05A in front of the shutter diode.  

Now, with 2W input to HAM1 and JAC unlocked, we should have 2mW on the REFL diode, and the shutter diode votlage is 0.18V.  The threshold of 2V now will shut the shutter with 22mW on it. 

Gaurdian changes:

The JAC error signals are normalized by the PSL input power if we use the laser power guardian to change the input power, so we shouldn't need a power scaling like 89708.  People have been using the rotation stage instead of the guardian to adjust the power because the laser power guardian would go into fault if the power was below 1W (people have been going below 1W while HAM1 is vented.)   Jenne Driggers adjusted the fault in LASER_POWER and added a 200mW state to the laser power guardian, so now we should use this guardian whenever we want to change powers, even below 1W. 

We also hard coded the gain used for locking JAC in the down state, although this could be reverted to allow the power normalization to work again, once that has been updated to take into account the new ND filters.  Once this was done, we could lock JAC at a variety of powers and also change the requested power after it was locked. 

Georgia B and I also had a look at the IMC guardian, which has not generally been able to lock the IMC except at 2W.  There was some code in the down state of IMC LOCK that was supposed to adjsut settings for lcokign at different power levels, these were unused except for the IN1 gain setting used for acquisition.  Georgia and I adjusted some of these numbers and watched if the IMC would lock, we didn't take much time to test it but we did once twice see the IMC lock with 10W + input power, so that is promising.