The EY Slow controls issue escalated overnight, DEV5 now has no communication with EY.

The link deteriorated over the course of 5 hours, starting at 23:24 Sat 19sep2026 and was completely lost by 04:23 Sun 20sep2026.

Trending the slave_count_actual for DEV5 shows it erratically drops from 127 to 1 over this time period.

I turned off the JAC heater servo at 23:45:00 UTC today to do a longer step response test over the weekend.

TITLE: 09/18 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: Corey
SHIFT SUMMARY: Keita worked more on PRMI and ASC, we now have working ASC MICH loops. We also locked DRMI around 23:00 UTC at ~68 and ~12. The pump down continues over the weekend on both ETMX and the X/Y BMs.
LOG:                                                                                                                                                                                                                                                                                

ASC-MICH loop works after ASC-AS_B rephasing (it looked nonsensical before).  I have no idea why they changed. AS_A phase was OK though not great, no adjustment was made.

Before making any adjustment:

I refined PRMI alignment manually, locked PRMI and measured the response of ASC-AS_B_RF45 used for MICH. I also measured AS_A just because.

In the first attachment (AS_B_RF45_VS_AS_A_before_phase_adjust.png), I'm misaligning BS in PIT both ways without enabling MICH nor PRC1 ASC feedback (but did enable DC3 and DC4 to center the beam on AS_A and AS_B) to test how AS_A and AS_B RF45 output respond.

MICH ASC error signal (AS_B_RF45_Q_PIT, yellow) is useless as it has a very small response to BS misalignment and it never crosses zero. This is what Elenna, Louis and I observed yesterday, too. In comparison AS_A_RF45_Q_PIT looks more promising (but should not).

In ASC-AS_B_RF45_phase.png, I'm injecting PRCL (not angle) dither at 80Hz to PRM M3 stage TEST_L and see the line in on each quadrant of each WFS. The idea is:

1. PRCL signal must appear in I phase (dashed lines) not Q (solid) for AS_A and AS_B quadrants (left panel, top is AS_B, bottom is AS_A) as well as the LSC sensor (H1:LSC-REFLAIR_A_RF45, the right panel). 
2. For each WFS, all quadrant signals in I phase MUST have the equal phase relative to the PRCL error signal at the dither frequency (middle panel).

As you can see, AS_B doesn't make sense. For all AS_B quadrants, PRCL line shows stronger in Q than in I, and the phase of the third quadrant is flipped.

ASC-MICH works after rephasing.

I made the following changes to roughly minimize PRCL line in Q AND to make the phase relation of all I signals the same relative to PRCL error:

The phase numbers themselves look more similar to each other now, PRCL line in Q phase is much smaller in all quadrants (ASC-AS_B_RF45_phase_after_adjustment.png), and most importantly, ASC-AS_B_RF45_Q_ERR responds to the MICH misalignment sensibly with good amplitude and it crosses zero (AS_B_RF45_VS_AS_A_after_B_phase_adjust.png). 

Dark offset adjustment might be needed, though.

Anyway, after this adjustment ASC MICH loop worked fine with ASC-MICH_P_GAIN and Y_GAIN of 0.5. See ASC-MICH_works.png.

Demod phase values were accepted in sdf.

Ryan C, Dave:

The Beckhoff CS-AUX-DEV5 slave_count_actual dropped from 127 to 0 five times between 08:01 and 08:07 this morning. As far as we know there is no Beckhoff work ongoing at this time. 

TITLE: 09/17 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: Corey
SHIFT SUMMARY: *I forgot to click post for this last night*

The LVEA was transitioned to SAFE, the CHETA viewports were installed, EndX pump down continues, and the HAM2 CPS cables were rerouted. Commissioners spent the afternoon touching up some corner alignment then they worked on PRMI and some phasing. A few optics lab and PSL anteroom dust alarms in the late afternoon, corresponding roughly with wind increase but the wind increase 3 hours previously did not increase the dust counts.

LOG:                              

• 14:30 UTC A 6.5 from the Aletians hit us
• 15:30 UTC LVEA to SAFE
• 18:30 UTC HAM2 cabling finished and corner alignment start, JAC work/alignment had been going on beforehand

TITLE: 09/18 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 5mph Gusts, 2mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.07 μm/s 
QUICK SUMMARY:

• Overnight Optics lab and PSL laser room dust alarms, 10k and 500 cts respectively
• Temps, and CDS look good
• EX pump down continues, the corner station X/Y BM pump downs will be resumed this morning

(Travis S., Jordan V., Richard M., Gerardo M.)
After the installation of CHeTA viewports, we connected an ISP-1000 scroll pump and a SS-500 cart to each of the main turbo pumps at the X beam manifold and Y beam manifold.  After getting power sorted out to the ISP-1000s, thanks Richard, we started the pumpdown for both of the manifolds.
Something that we did noted was the new gauge for PT-180 shows almost 1000 Torr for pressure at atmosphere, this is not correct, then the other gauge for PT-170 shows 750 Torr for pressure at atmosphere, also not right.
Pumpdown has been stopped at the end of the day, and will be restarted tomorrow morning by Jordan.

Attached is a plot of both manifolds initial pumpdown.

[Elenna, Louis]

After the HAM2 work (91959) finished today, we decided to double check AS port powers in a couple states. I trended back about a week to September 10, long before the RCG upgrade (91936). We are seeing a ~20% drop in counts on AS_A and AS_C in PRX_LOCKED and SRY. Also, our PRMI buildup right now is about 56. Last time we locked PRMI without ALS it was 52.

* Not sure how comparable this number is since we don't know much about the centering on the LSC POP diode at the reference time. POPX pit & yaw are ~ -1 during this reference time stretch.

After we locked PRMI today, I tried to engage the MICH ASC. The first try failed, so I tried engaging by hand. I had previously phased the AS B RF45 signal to maximize MICH length in Q, so I thought the error signal was fine.

Then, I checked the MICH P error signal. I first moved PRM and BS to try to maximize the POP18 buildup. Then, I tried moving BS pitch to check if the error signal crossed zero when the signal was maximized. That did not happen.

So I checked the phasing again- three segments needed to be adjusted to improve the phase.

Then, I tried my error signal test again. It still does not cross zero.

I attached my phasing attempts and the SDF, but maybe I am not phasing this correctly- maybe it is better to check in a MICH fringe.

Over the last few days, Oli and I removed four unused chiller lines at the Yarm termination slab. Two were old TCS lines that were already cut off and mostly empty, the other two were valved out around the spool area but unused after. We cut, vacuumed, and removed all the copper pipes and their support hardware up to that spool area. Still to do is solder an end cap to the two cut lines.

WP 13630

The PTZ camera used to document the BSC2 dome and cartridge install/removal was uninstalled. Camera will be deleted from the access system camera log.

(Travis S., Jordan V., Gerardo M.)
Today we were only able to vent the YBM (manifold on the Y-Arm), to do so, we hard closed GV1, GV2, GV5 and GV7.  GV5 and GV7 are pneumatic valves, they closed with pressure of 25 psi both, very good pressure.  Then we measured the purge air dew point, -42.1 ^oC.  One issue that we encountered was that it took a while to vent to atmosphere, the wide range gauge at PT180 is way off indicating 998 torr for a vented to atmosphere volume, should be more like 762 Torr today, we will check on how to reset that value.
Vacuum envelope for the YBM is vented and ready for the viewport work tomorrow.  However, the manifold for the X-Arm still under vacuum, no work should take place there until fully vented.

After closing up BSC9 yesterday we started pumpdown of the EX volume this morning using the two mobile ISP1000 scroll pumps.

There was minimal overpressure in the system, so I could not get a good dewpoint measurement of the blow down air.

It took ~6 hours to rough the system down from atmosphere to ~500 mtorr, where we start the turbopump.

The cooling water was adjusted on the turbopump stand so that the pump and controller pressures were <= 40C. Once the turbo was at full speed and the inlet pressure ~5e-5 Torr, I switched the backing pump to the dedicated ISP250 on the turbo stand.

Setpoints were adjusted to 5E-2 Torr on Channel 1 (Foreline) and 5E-5 Torr on Channel 2 (Turbo inlet).

We will need to leak check the TMDS port gate valve since it was removed to verify the gate o-ring was in place.

Also, the EX cleanroom was powered off at ~3:10 pm local time.