Late entry.
Activities at 1-25:
- The RGA was completely rebuilt at EX, and the RGA tree was already leak checked. Currently it is pumped, and it is already at the E-9 Torr region
- The 12" 3IFO feedthrough was replaced with a blank on BSC5 at EX
- The spare roughing stations were completely finished
So far, everything went as scheduled.

Mechanical

• Alignment check: Confirm if the current mechanical Pitch/Yaw of OMC3 and OMCS are sufficient. -> (If not, touch OMC3 and OMCS more)
• Check the bias values of OMC1/2/3 and OMCS ->(Do we need any debias?)
• Check if the OSEM DC values shows the light close to half shadowed.
• Check if the TFs of the OMC1/2/3 and OMCS are still acceptable.
• Adjust the WFS / OMCR paths
• Restore the shroud panels
• Restore the OMC trans beamdump

Electrical tests:

• PZT1 test
• Fast Shutter functionality/delay time test

So far, the O4 break vent & commissioning work is proceeding as planned, with only minor hiccups.  Yesterday's TCS water leak caused a pause to the HAM6 in-chamber OMC alignment work, but we were able to resume this morning pretty quickly with only a short amount of time down.

The attached snapshot shows the planned schedule outline with green checkmarks next to the items completed so far on the left hand side.  On the right is a running log of the activities which have taken place daily (for ease of viewing all in one place).

Teams currently on:

• HAM6 new OMC in-chamber alignment
• EX prepping to pump down post cryo baffle damper install, ETMX SUS appears healthy with few TFs spot checked
• Prep for HAM3 baffle work next week, chamber cleaned
• Starting EY wind fence repair
• TCS system maintenance
• FARO setup in LVEA for monument surveying

Summary:

We restarted the alignment work. The angle and/or the position of the new OMC relative to the cage is significantly different from the old one, and we had to mechanicaly rebalance not just the OMC, but OM3 and OM2 too, and rotate the cage of OM3. We'll see if these were good enough tomorrow.

1. Rebalancing the OMC

Yesterday, we rebalanced the OMC, the beam was on both of OMC QPDs but we didn't have time to touch up OM1 and OM2 to center the beam on OMC QPDs.  This morning we centered the QPDs and relieved the PIT offset of the OM3 as much as I could by using OM1 and OM2. Then we did another push of the balance mass, recentered the QPDs, and relieved PIT offsets of OM1/2/3 such that everybody kind of equally suffer. We ended up doing four iterations of this in total.

Following is the PIT/YAW offset slider values (ASC output to OM1/OM2 due to earlier WFS centering was already folded into these numbers).

Note1: OMn (n=1/2/3) sliders are not calibrated. Due to different EUL2OSEM matrix, OM2 apparent "range" for the sliders is about a factor of 1.7 larger than OM1 and OM3 (i.e. if you compare OM1 and OM2 coil output, the latter has a factor of 1.7 smaller output than the former given the same slider offset).

Note2: By "centering", we really mean centering w/o offsets. Since the position of the QPDs relative to the cavity mode differs from one assembly to another, there's no reason to assume that the good QPD offsets for the new OMC will be the same as the old one.

2. Beam height measurement, beam centering on OMs

At this point Koji measured the beam height at OM1, OM2 and OM3.

The beam was about 3/64" or about 1mm too high on OM1 (it was 5mm higher than 4" in the past) but it was too low on OM2 by ~16/64" or about 6mm. It quickly went up from OM2 to OM3 where the beam height was about 2/64" or about 0.8mm too low. The beam was clearing the input hole of the OMC shroud cleanly, and the OMCR beam was level.

These meant that OM2 was excessively tilted up and OM3 excessively down, both mechanically. Koji and I agreed that this is most likely due to the difference in angle for the old and the new OMC.

1/4" mis-centering on OM2 sounded too much to ignore to me, so we decided to bring the beam up at OM2 by using OM1 bias, and mechanically relieve the PIT of OM2/OM3 and YAW of OM3.

We're done with the 1st round of mechanical relieving. We adjusted OM2 PIT. We adjusted OM3 PIT and rotated OM3 cage for YAW while making sure that the beam is at least partially visible on both of the QPDs. After centering QPDA, the following shows the numbers as of now.

Overall, this looks to be a good improvement, but the beam is still hitting QPDB at the edge. We still have to see if it's possible at all to center both QPDs without further mechanical relief.

3. PZT and DCPD electronics are working

Koji scanned the OMC PZT and saw flashing on the DCPD A as well as B. PZT as well as the DCPD preamp are working.

Remaining tasks:

Center the OMC QPDs using mostly OM2 and OM3. If further mechanical relief is required, do.

After the OMC QPDs are centered, confirm that OMCR path is still reasonably level. Center the beam on the OMCR DCPD.

Center the AS_A and AS_B.

I don't know how to confirm that the OMC transmission will still hit the viewport for the camera. We'll try to use the card and the viewer combined.

Check the grounding.

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)

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.

[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.