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.

Wed Jan 24 10:05:46 2024 INFO: Fill completed in 5min 43secs

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.

Per WP11624 replaced the squeezer slow controls Kepco power supply due to issues had with it in ALOG75331.

Old Kepco Serial Number = S1201988

New Kepco Serial Number = S1201903

Temperature and airflow measurements in new supply are similar to the old supply.  I suspect the thermal cutoff on the old supply is not functioning correctly.

[Measurements attached]

FAMIS LINK:  25975

BSC CPS:  Received following from CPS script terminal output:

• ETMY_ST2_CPSINF_V2 high freq noise is high!

NOTE:  If one was to follow the above channel as an example, it would seem several other BSCs had CPS' with spectra similarly high by eye:

• ITMx ST1 V1

HAM CPS:  Looks good.

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
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 4mph Gusts, 2mph 5min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.27 μm/s
QUICK SUMMARY:

• LVEA is laser HAZARD.
• 8am Coordination meeting in the Control Room.
  • Return to HAM7 in-chamber work
  • EX chamber port work begins at 9am for whole day (Robert)
  • Discussion of X-arm burning beginning in Feb.
  • EY light work (Ken)
  • HAM6 work continues
  • Next week LVEA most likely laser SAFE
  • FARO work continues
  • CO2 laser swap
  • HAM3 cleaning needs coordination with Karen/Kim/Chris
• FOMs with ndscopes froze after the DAQ restart yesterday!

Rick and I went to EndY to do the PCAL Tx module maintanence today.
We followed Mostly followed the procedure outlined in DCC doc T1600436-v11 which was printed out and attached to the ALOG.
I have also updated the PCALTxMaintenanceLogBook spreadsheet with the latest information from today's activity. This is information is now in the DCC with an updated version number.
Attached a picture of the OLTF taken with the SR785 .
And a beam spot with both beams after we were finished cleaning and measuring.

[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.

Today's activities:
- The RGA tree at EX was leak-checked, and multiple flanges were leaky, possibly because of some overheating during a bakeout in the past. The gaskets will be redone, and the all-metal angle valve will be also replaced
- EX was vented
- The VPW vacuum chamber was opened, after the 2 stuck screw was removed
- Both 2 spare roughing stations are entirely finished
- All the Hepta header filter works were finished in the LVEA

[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