TITLE: 01/26 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: SQZ laser was turned back on and LVEA moved back to Laser Hazard, work continued at HAM6, wind fence repair was started, HAM3 was cleaned in preparation for opening.
LOG:

16:35UTC Team going into LVEA to check on the status of the TCS water leak
17:30 Squeezer laser okay to get turned back on; gets turned on
18:19 LVEA transition to LASER HAZARD

Fil, Jonathan, Erik, Dave:

At EY Fil found h1susauxey has its front panel FAIL LED lit. He tracked the issue down to a failed power supply. This is a redundant dual power supply system.

Strangely this system is not beeping, which is the default behaviour if a power supply unit is inserted but not operational.

The IPMI shell confirms that the system has correctly identified the failure:

ipmi sensor output:

  OK     | (2751) PS1 Status        |           Presence detected           |
  Fail   | (2818) PS2 Status        |     Power Supply Failure detected     |
 

TJ, Jason, Camilla, Fil.

WP11612, FRS25384, swapping because current CO2X laser was slowly deteriorating, details in 75249.

Removed: Access 50LT 20706.21015D. Installed 20306-20419D, which was refurbished/re-gassed in March 2020. Table layout: T1200007.

• On Tuesday 23rd:
  • Checked polarizers on both CO2X and CO2Y (pictures) and spares were fine after issues at LLO (FRS30220). Will update FRS with details. 
  • Added labels to RF cables and water tubes on CO2 laser and RF driver.
  • Scribed current position of CO2 laser and photographed.
• On Wednesday 24^th AM:
  • Placed beam dump in front of periscope.
  • Remembered L1 has some damage on lens, caused by the plastic lens ring, photo. In future we should use metal lens rings.   
  • Turned on CO2 laser.
  • Check position on FLIR, with no mask, central and annual masks (needed to turn on FLIR – power supply inside enclosure).
  • Checked beam is going though all irises with beam card kit and FLIR one camera. Pictures
    • On masks: beam slightly high/masks low
    • On irises – beam a little low, but well centered with masks in.
    • Will not adjust irises 
  • Turned off: chiller, power supply, RF and power supply in mechanical room mezzanine,  AA chassis
  • Disconnected water lines (outside CO2 table). Drained table lines with gravity and wet-vac.
    • The small on table water lines have a lot of old contamination in them, photos of RF driver and CO2 lines, comment added to FRS10612 so we can think about replacing these lines post O4. 
  • Disconnected all cables and water pipes to CO2X/RF driver and removed laser and RF driver. 
  • Installed new CO2 laser (needed to move back foot back one set of bolt holes and turn water connections around 180deg). 
  • Installed new RF driver after Fil reattached it's electrical plug
  • Reconnected all cables and water pipes (expect table to main line connection). Photos of installed laser and RF driver.
  • Powered on CO2X chiller (had been turn off in medm so usually wouldn't turn on but it did)
  • The CO2X water pipe coming from the mezzanine leaked under the high pressure (as not yet connected to table), spraying water onto the cable trays above SQZ0/SQZT7 and SQZT0. 
  • Betsy initiated stop work M2400022, we transitioned to laser safe and Fil disconnected electrical connections. 
  • Richard, Fil, Jason and TJ dried the area as best they could. We see no sign of water inside SQZT0. 
  • Will reassess next steps on Thursday 25th. 

Still to do after the CO2X cooling line issue is solved:

• Refill table with water and reconnect to chiller.
• Turn on laser in PWM mode for low power realigning.
• Realign laser to irises and FLIR camera using M1 and PM1 mirrors
• Measure power out of laser head using S322C
• Check alignment to power meter and masks
• During commissioning time: spend ~2 hours realigning in-vac using HWS and periscope picos. 

Thu Jan 25 10:02:32 2024 INFO: Fill completed in 2min 30secs

Robert, Mitchell, the vacuum team, the SLiC team

This morning we opened up 3 viewports and inserted dampers in between the baffle and the beamtube wall (Fig. 1). I was able to gently move the baffle, using the ”rails” of the eddy current dampers as position indicators in order to adjust the dampers to return the baffle to its original position. Before/after measurements did not deviate by more than 1/16 of an inch.

I used the laser vibrometer shining through a viewport to monitor the baffle. Figure 2 shows time series for beam tube impulses, indicating that the damping reduced the Q from about 400 to about 20 for the problematic 4 Hz peak. Thus, the cutoff frequency of the scattering shelf during high 4 Hz vibration levels should drop from the typical 50 Hz to about 2.5 Hz (so mostly just the 4Hz peak should remain and not harmonics). The second page of Fig. 2 shows before and after laser vibrometer spectra, which show that the main peaks did not move much, and adds evidence that the baffle is unlikely to be rubbing.

The viewports were closed this evening.

Today's activities:
- 3 viewports have been taken off at EX for baffle works. These have been inspected, and found intact in every aspect - the inspection report is in the comment section
- These viewports have been already taken back, as the works were already finished
- The EX RGA is being rebuilt after many leaks have been found - it is in progress, will be finished tomorrow
- The new Hepta header elbow pieces have been staged at all stations

Following the installation of the new OMC yesterday ( alog 75529), we started aligning the laser into the OMC.

Preparation:

Vicky enabled the WFS centering to center the SQZ beam (LOCKED_SEED_DITHER state) reflected by the SRM on AS_A and AS_B. At this point almost nothing was visible on the OMC QPDs.

We increased the whitening gain of the OMC QPDs (H1:ASC-OMC_A_WHITEN_GAIN and H1:ASC-OMC_B_WHITEN_GAIN) to 45dB from the original 0dB and reset the dark offset.

Initial beam search. Beam visible on OMC QPDs only when OM3 is totally railed in PIT no matter what:

We started scanning OM3, and saw nice beam at the edge of both of the QPDs but only when OM3 was completely railing in PIT. 

We disabled the WFS centering and started using OM2 and OM1 to make the beam more centered on the OMC QPDs. I was able to make it somewhat better but not really, and more importantly, no matter what I did, I could not releave OM3 PIT offset at all. Whenever I removed a bit of OM3 PIT and tried to use the combination of OM1 and OM2, I was only able to make it worse.

I also used OMCS offsets, but it made no meaningful impact as  the alignment was so bad and the OMCS range so small.

Diagnosis and mitigation part 1, things are making sense:

These all indicated that the OMC has a big PIT tilt relative to the old OMC. This was corroborated by our observation yesterday that one corner of the OMC breadboard was hitting the EQ stop structure and we couldn't release the OMC without moving the EQ stop bracket itself down. According to alog 75529, "We noticed a corner of the OMC on the HAM5 side was bottoming on an EQ stop. We decided to lower the EQ stop by releasing the fixing screws for the EQ stop holder. The holder was tilted, and the OMC became free."

With this knowledge, we went back to HAM6 to rebalance the OMC suspension in PIT.

Rahul and Koji pushed the PITCH Insert mass (part number 14 in https://dcc.ligo.org/D060502) by about 5mm into the direction of HAM7. We immediately lost the beam on the OMC QPDs, but relieving the PIT offset by 1000 counts (out of the total of 3500 counts), we regained the beam, so the adjustment was in the right direction.

The intermediate conclusion is that OMC breadboard is tilted in PIT such that the long edge at -X side was too low. We at least partially relieved it by tilting the intermediate mass to counter that.

I thought that another step or two would be great, but at that point we had to stop our work. We'll continue tomorrow.

TITLE: 01/24 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

• Late Update:  (Water leak during TCS laser swap near SQZ table(s))
• EX baffle & TCSx CO2 laser swap work begins.
• OMC (HAM6) alignment in control room & then work on changing balance of OMC, but could not complete due to TCS leak.
• LVEA is now laser SAFE
• EX baffle "in-tube" work complete & ready to seal up EX by VAC.

LOG:

• 1545-1713 EY wind fence prep (randy)
• 1555 LVEA cleaning (karen.kim)
  • 1626-1736 EX & MX checks/cleaning (kim)
• 1610-2130 EY lights & EX fiber weld electronics work (ken)
• 1616-1636 Opening HAM5/7 gate valve for HAM7 work (camilla)
• 1621-1633 Grabbing parts in lvea (jordan)
• 1631 MY air handler high temperature alarm (from 65 up to 110degF), notified Tyler.
• 1634-1650 Looking for VAC parts for EX in LVEA (travis)
  • 1722 Parts searching again.
• 1636-2130 Escorting Fire Systems contractor to a Mid-Station, Filter Cavity End Station, and OSB (eric.tyler)
• 1651 CO2x Laser swap work (camilla, tj, jason, ryanS)
  • 1837-1855 Coffee break!
  • 2015-2134 lunch break
• 1706-1722 LVEA Output Tube dewpoint measurment (jordan)
• 1715-1718 LVEA checks (mitch)
• 1730 EX Baffle work (robert, mitch, VAC team)
  • lunch break
  • 2329 inside work complete!
  • 2329 VAC needs to start sealing up.
• 1730 EX rga work (VAC team)
• 1749 lvea crane prep work (randy)
• 1805-1840 EX check of fiber welding recepticle (richard)
• 1820-1840 Working with TCS team (karen)
• 1850-1920 Checking up on EX work (betsy)
• ?? - 1952Finishing up aligning of OMC from Control room (Keita, Koji, Rahul)
• 1950-2052 SQZT0 photos (daniel, vicky)
• 2049-2323 OMC re-balancing (koji, keita, dana, rahul)
• 2052-2117 Continuing prep for moving items in lvea (randy)
• ? - 2324 EX Baffle afternoon work (robert, mitch)
• 2135-2157 MY to pick up parts (marc, jabari)
• 2211 Checking HAM6 work (betsy)
• 2227 TCS Water leak around Squeezer table (tj notified control room)
  • A "Stop Work" is currently in effect due to this & Mike (& involved parties) will start composing the documentation for this.
• 2238 Checking on LVEA work (richard)
• 2240 LVEA Transitioned to Laser SAFE
• 2300 Checking on LVEA activities (mike)
• 2302-2315 Checking on state of Squeezer (daniel.sheila.vicky.naoki)

For the record, late alog - a couple weeks ago the EY wind fence was found to be damaged, again from early JAN severe winds (50+mph gusts for a few days).

Plans are in place to repair it with an improved round of reinforcement.  A second snorkel lift is being delivered to aid in the repair scheduled for ~next week.  FRS ticket filed.

Naoki Vicky Daniel

We physically placed the PMC, the RF photodetector, and a bunch of steering mirrors into the empty space on SQZT0. Everything seems to fit as planned. No beams yet!

We also installed the Thorlabs PDA100A that serves as the PMC_TRANS monitor. It is installed along the seed path. There is a 50:50 splitter that reduces the seed power by 2. We installed a one-side AR coated wedge in the path of the beam dump to get about 19mW of light that we steered onto the PDA100A.

The slow controls system was upgraded to add new channels associated with the PMC and update some channels names. There is no longer a FIBR_REJECTED PD, instead we added a FIBR_INPUT PD that monitors the fiber power from squeezer laser in the beat note box.We no longer have a monitor for light in the wrong polarization at the laser locking beat note. Instead, we have to use the beat note strength to optmize the input polarization.

[Rahul Betsy Keita Ali Koji]

The extraction of the old OMC (Unit #3) and installation of the new OMC (Unit #1) went exceptionally well.

= OMC Extraction =

Tuesday morning, we resumed HAM6 work from the OMC extraction.
Rahul and Koji went into the chamber. Rahul positioned close to HAM5, and Koji was on the other side.
They followed the extraction procedure (E1600164) after some rehearsals.

• Unhooked the wire clamps on Rahul's side.
• Unhooked the wire clamps on Koji's side.
• Lifted the OMC from both sides and extracted it to Koji's side.

During the OMC extraction, assistance from two others was very effective in supporting wires from both HAM6 openings, preventing the wires from touching the OMC. (The procedure to be updated)
The extracted OMC was placed in the fixture on the ISI and moved back to the work table for further action.

= Balance Mass Migration =

Balancing masses were transferred from the previous OMC to the new one (Attachment 1). At the same time, a Viton ring and a 10g mass were added to each corner for the body mode damping (See T1700471).
The mass distribution differed from what Koji had figured out from the past unclear photos. But the masses could be fixed to the OMC using various 1/4-20 screws that were prepared for this.
Only light torque was applied to the fixing screws to avoid delamination/fracture of the mounting brackets below the mass mount.

= Final OMC cleaning =

All the optical surfaces were cleaned by FirstContact except for a couple of surfaces where the access was quite limited. (Attachment 2)

We let the FC paint dry during lunch and then resumed peeling them off, combined with discharging with Top Gun.
The surfaces were checked with a flashlight to find any residual.
A FC residual was located not on the optical surface but on the corner of a tombstone prism. It was cleaned with additional FC paint.

In parallel with the cleaning work, Ali and Keita worked on the review of DCPD-related cable shielding in HAM6.

= OMC Installation =

The reverse process of the extraction has been performed.

• Brought the OMC in the OMCS frame
• Hooked the wire clamps on Rahul's side.
• Hooked the wire clamps on Koji's side.

When inserting the clamps into the clamp hooks, sometimes incomplete mating happens due to friction between the copper cone and the frosted glass cup.
This can be fixed by pushing the clamp into the slit by a small flat-head driver, while the tension on the wire was released by lifting that side of the OMC.

= EQ stop release =

Reverse process of the OMCS mass clamping.

• OMC EQ stops were released:
  We noticed a corner of the OMC on the HAM5 side was bottoming on an EQ stop.
  We decided to lower the EQ stop by releasing the fixing screws for the EQ stop holder. The holder was tilted, and the OMC became free.
• IM blade stops (Qty 4) released
• IM EQ stops 1/4-20 hex nuts (Qty 2) released
• IM EQ stops (Qty 12) released
• Top blade stops (Qty 2) released

This made the OMC free. Rahul quickly checked the transfer functions of the OMCS as well as the damping control.

We decided to stop here. (Attachment 3)

Next Steps:

• Beam alignment
• Possible suspension alignment
• Check electrical connections
• Reinstall the OMC shroud panels

[Julian, Naoki, Camilla, Sheila, Vicky]

Summary to get SQZ alignment beam: Launched 76mW into seed fiber, ~25 mW incident on opo cavity, ~0.85 mW transmitted through opo cavity. Had to find opo transmission past the VIP, for this we used green SK path as a reference. This ~0.85 mW opo transmission was bright on an IR card at the HAM5 gate valve, and enough to iris the SQZ beam in HAM7 and HAM6 (for OMC work 75512). DC 3/4 centering loops engaged easily, then OMC A/B QPD's saw the sqz beam.

----------- Notes from today ------------------------------------------

Launched power into SEED fiber (SQZT0): 76 mW

OPO IR REFL (CLF_TRIG_REFL_DC_POWERMON @ SQZT7): 24.8mW   (when opo is dither-locked).

Fiber rejected power PD in HAM7 (CLF_REFL_REJ) is 5.3 mW.
  -->  Seed fiber coupling: ~34% of the seed fiber launched power was incident on the opo cavity. 
  -->  40% coupling through fiber, ~6% mispolarized and rejected after fiber. This is similar to recent fiber alignment 75344, even after more recent on-table work 75486.

We had to find the OPO IR transmitted beam after the VIP. Nothing at first despite restoring suspensions 75502. Notes to self on what worked to find the SQZ beam post-vent:

• Started with no opo trans after the VIP, despite checking SQZT7 periscopes and the HAM7 RLF QPD's (which we use for FC WFS).
• 75502 saw ZMs had shifted after vent. Naoki 1) offloaded all FC+SQZ ASC and set all PSAMS offsets back to "nominal", then 2) he and Austin restored ZM1-6 + FC1 slider values to the same P/Y damp values as we last had in observe. Still did not see beam past the VIP (nothing on RLF QPD's, nothing on SQZT7 IR camera).
• SK path was helpful to find the VIP transmitted beam.
• Looking at the bottom SK periscope mirror on SQZT7 like here, we walked FC1 P/Y sliders to overlap FC_GR_REFL (which sees FC REFL), with OPO_REFL (which does not see FC REFL, and thus is a good alignment reference for the FC REFL path including ZM1-2-3-FC1).
• Used FC1 P/Y sliders to overlap FC_GR_REFL with OPO_REFL (looking at an IR card on the periscope lower mirror). While doing this, we found OPO IR TRANS on the RLF QPD's.
• Then we walked FC1 and ZM3 to maximize transmitted power, ie OPO_IR_DC_POWERMON. Not totally optimized, but seemed reasonable to keep going.

OPO IR TRANS (OPO_IR_PD_DC_POWERMON @ SQZT7): 0.85 mW  -- Just before opening the HAM7/5 gate valves. Opened the beam diverter, SQZ beam was bright on an IR card held at the HAM5 gate valve.

After opening gate valve, immediately saw the beam on AS A/B/C QPDs.

ASC-AS_A/B_DC_SUM_OUTPUT ~ 60.  ASC-AS_C_NSUM_OUT16 ~ 0.65-0.67.  

HAM6 crew irising SQZ beam, 75512.

HAM7 crew irising SQZ beam. Julian has some photos of HAM6 and HAM7 irses. Sheila -- looks like there is some clipping on the VIP (we have not totally optimized FC_REFL path slider alignments post-vent, just found the beam). Revisit this FC REFL alignment later.

Engaged DC 3/4 centering. It just worked. Control signals near 0. 

We see the beam on the OMC QPD's, power is consistent with ASC-AS_C power, around 300-400e-6 on each OMC QPD A/B. Power goes away when SQZ beam diverter is closed. See omc powers screenshot with as_wfs powers.

TO-DO SQZ work later:

• more photos of HAM7 irises
• measure sqz beam powers with power meter
• undo VIP clipping (using e.g. FC1/ZM3) - we didn't fully optimize this FC REFL alignment yet after venting.

[Rahul, Keita, Betsy, Koji]

Preparation work to extract the existing OMC has been completed. We will continue with the OMC extraction tomorrow morning.
The overall work procedure for the OMC replacement is summarized in G231106 https://dcc.ligo.org/LIGO-G231106.

= OMC shroud panel removal =

While waiting for the beam from the squeezer to come, we started the removal of the OMC shroud panel in parallel. The work was done along with the procedure E1600164.
The removed panels were placed on a stainless steel table in the HEPA booth of HAM6 (Attachment 1). The panels were not covered to prevent accidental placement of objects on them.

During the work, a beam dump was removed from the table to make the removal work possible. This beam dump is to kill one of the weak transmissions of the OMC.
Betsy took the photo record of the location, but it is safely trivial how it should be aligned.

= SQZ beam marking and alignment =

The beam was delivered to HAM6 and was pinned down with two irises on the ISI table.
The irises were placed just after the beam entered HAM6 (next to OM2) and just before OM1 (next to the fast shutter).
This means that these indicators are not affected by the alignment in HAM6.
They were placed by eyeballing, so their precision was as such. By default, both the irises were set to the maximum opening.

Next, the beam alignment was servoed towards the WFS heads using the DC centering ASC loops.
As soon as the control was applied, both QPDA and QPDB of OMC showed significant signals with total light level of ~1e-3 (Attachment 2).
When the light was blocked (at the squeezer?), the value dropped to almost zero, confirming that this was a real beam.
This is very good news as we'll be able to find the beam arrival using the OMC QPDs when we try to align the new OMC.

= Holding suspension mass =

Next, we proceeded to hold the suspension masses. Rahul and Koji worked in the chamber on the ISI table for the following operations.

To hold the intermediate mass:

• First, the top blade was fixed with stopper screws.
• Next, we tried to fix the middle mass with two 1/4-20 nuts, but this caused some wobbling of the suspension. So, we first decided to fix the middle mass with smaller side EQ-stops. This process has not been described in E1600164. (to be updated)
• Once the middle mass was fixed horizontally, the vertical dof was also fixed firmly with the small EQ-stops and the 1/4-20 hex nuts.

Then, moved onto fixing the OMC:

• The bottom EQ stop for the OMC was left as they could not touch the OMC. The side (long side) EQ stops were extended and are holding the OMC horizontally.
• The Top EQ stops for the OMC were removed by removing the L-shaped brackets on both sides.

= Removing the electronic cables from the OMC =

Upon removing the electronics cables, one person held the cable harness on the OMC breadboard to prevent the OMC from wobbling too much.
The removed cables were wrapped around the top part of the suspension frame to keep them out of the way of the further work.

At this point, it was just at 5pm, so we exited from the chamber.

Next Steps:

• Extraction of the OMC
• Migration of the balance masses to the new OMC
• Final cleaning of the new OMC
• New OMC installation