The FMCS Reverse Osmosis (RO) system has been error free for 10 days following the water leak repair. Its alarms have been returned to the CDS cell phone alarm system.

Following the crash of h1susauxh2 over the weekend, I reviewed the alarm configuration to see if we would get cell phone alarms if something happened to h1edc which runs on h1susauxb123. To this end I have added two new alarm channels to the alarms system.

Both of these changes went into effect at 13:20 PDT when the alarms.service was restarted on cdslogin.

A Norco tech came to the site to inspect the 8 LN2 dewars that feed the cryopumps. Inspection report will be posted to Q2000008 once received.

- No major issues found, some small leaks were repaired as they were found

The vacuum jacket pressures were also measured during inspection:

The vacuum jackets were all pumped down to <10 mtorr last May (excluding CP4 which is not in use), see alog 77742

Fil Marc Daniel

We noticed that the photodiode pins of the in-air cable that connects to RM1 and RM2 were flipped. This will flip cathode and anode which will only matter if there is a bias applied.

Going thru the schematics it seems that with 1:1 wiring the PD anode and cathode are flipped compared to what is shown in Sat Amp D080276. I assume somebody noticed this and flipped the corresponding pins of the in-air cable to correct for it back in 2013.  The polarity of the PD doesn't really matter, if there is no bias. We checked the RM sat amps and they have no bias.

If the Sat Amp PDs are connected as shown om D080276, the OSEM values will be negative. Indeed, the RMs had negative OSEM values as expected. However, all ZMs have positive values, since nobody bothered to flip the pins. We propose to no longer flip the PD pins for the RMs and work with positive OSEM values in the future.

WP12472 POP_X and LSC_REFL_B changes

Daniel, Erik, Dave:

New h1lsc and h1asc models were installed at 12:50 PDT. No DAQ restart was required.

h1lsc restart caused TIM errors in h1ioplsc0 and h1sqz.

FAMIS 31082

Generally, things are stable following the three days of work in the enclosure for the SPI pick-off path install last week, which show clearly on several trends. Most notable is the decline in PMC and RefCav transmission, which have significant misalignments as seen by the beam spot cameras. Fil and I plan to switch the connection of the picomotors to their new driver tomorrow, so after that they'll be usable again and I'll touch up the alignments.

Also, we have still not increased the pump currents for AMP1 as we noticed last week following the power outage. This should bring the power out of both amplifiers and the PMC closer to their levels pre-outage.

Mon Apr 21 10:08:36 2025 INFO: Fill completed in 8min 32secs

FAMIS 26393

Laser Status:
    NPRO output power is 1.843W
    AMP1 output power is 69.23W
    AMP2 output power is 139.7W
    NPRO watchdog is GREEN
    AMP1 watchdog is GREEN
    AMP2 watchdog is GREEN
    PDWD watchdog is GREEN

PMC:
    It has been locked 3 days, 15 hr 20 minutes
    Reflected power = 23.37W
    Transmitted power = 104.4W
    PowerSum = 127.8W

FSS:
    It has been locked for 3 days 15 hr and 20 min
    TPD[V] = 0.6888V

ISS:
    The diffracted power is around 4.0%
    Last saturation event was 3 days 15 hours and 20 minutes ago

Possible Issues:
    PMC reflected power is high
    FSS TPD is low

Morning dry air skid checks, water pump, kobelco, drying towers all nominal.

Dew point measurement at HAM1 , approx. -42C

TITLE: 04/21 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 3mph Gusts, 1mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.14 μm/s
QUICK SUMMARY:

VAC Team reports that the corner's pressure is currently 2e-6 Torr 

• Trello tasks that may be worked on today:
• Corner Pump Down Continued or Lifted, STANDOWN OF HAM1 IN-CHAMBER WORK - check pressure
• 8:30am MEETING - check with VAC on lift of Stand down due to corner pumping
• Check on & Continue work from last week
• HAM1 ISI Sensor health checks, cabling
• HAM1 - ISI Payloading of center masses
• HAM1 - IAS alignment

I made a couple of ancilliary investigations while I was in-chamber helping adjust CPY. First, I shined a flashlight through the ITMY elliptical baffle towards the BS. Figure 1 shows that this produced a 45 degree annular beam, similar to the one observed during lock that I noted here ( 83050 ) , consistent with the hypothesis that it is a reflection from the BS cage (see linked alog).

Second, our entry through BSC8 also reminded me that LHO has some unique potential scattering sites that LLO does not have.  Figure 2 shows that several of the blanked off nozzles in BSC8 act as corner retroreflectors visible to the beam spot on ITMY, and there is a reflection from the chamber, just below the beam.  A look at my compilation of beam spot photos from several years ago ( 41142-Figure3 ) also shows these issues at ITMX (second page of Fig. 2). We should probably put in nozzle baffles next time we are in-chamber near BSC8 and 7.

I recently reported on multiple potential stray light issues in the vertex area, including a 45 degree conical annular beam from the beamsplitter, and a reflection of the halo of the beam passing through the ITMX elliptical baffle that is roughly directed at ITMY (83050). In a first attempt to study potential scattered light noise problems from these beams, before the break I injected 0.2 Hz X and Y motion onto the BS HEPI, with motion amplitudes of about 1e-6 m at stages, 0 and 2 (see figure).  The figure demonstrates with spectrograms and spectra (second page), that there is a slight increase in DARM noise for both X and Y injections,  mainly below 60 Hz. I turned the injections on and off multiple times because the noise is pretty subtle. I think we should further study these potential scattering issues after the break.

Sun Apr 20 10:09:17 2025 INFO: Fill completed in 9min 14secs

Here's a quick summary of the Estimator installation from this week (Edgard, Oli, Jeff K, Brian L)

slides with basic info: T2500082 
FRS ticket 32526

Installation alogs
Infrastructure installed on HAM2/PR3 and HAM5/SR3, style updates to model, MEDM linked to sitemap - alog 83906

Tools installed in Estimator folder in the SUS SVN alog 83922

We updated the OSEM 10:0.4 calibration filters, but only on SR3 and PR3. alog 83913

Damping filters installed - alog 83926

Tested the fader switch - alog 83982

Designed and installed a blend for SR3 Yaw (DBL_notch in the first filter bank) - alog 84004

Created a new OSEM calibration script - alog 84005
(Edgard is thinking about a general version of this using Python, that is still TBD)

Fitting is well underway, but isn't done yet.

We made much more progress than we expected - thanks Oli and Jeff for all the help. It's not quite ready to go, we need to install the TF fits for the model.

We might have actually been able to test, except the temperature changes from the pumpdown were causing the SR3 optic to move, and the TFs were not very stable. Edgard is working on a log to document this. We have good fits for SR3 yaw taken Friday morning, and we might just try these remotely with Oli's help. We do plan to get a clean set of TFs in a few days when things have stabilized.

-- notes for next steps, thanks to Sheila for this --

We plan to leave the SR3 overall yaw damping gain at -0.5. This means we'll set the 'light damping' to -0.1  and the gain in the estimator to -0.4. Edgard used -0.1 for the fitting, but he notes that the Q's are pretty high so we may need to revisit this.

SR3 oplev channels are : H1:SUS-SR3_M3_OPLEV_{PIT,YAW}_OUT_DQ

Some interesting alogs about the impact of changes to SR damping: alog 72106 and 72130  

Elenna's PR3 coherence plots: alog 65495

Sat Apr 19 10:08:32 2025 INFO: Fill completed in 8min 29secs

h1susauxh2 models stopped running 23:43:02 Fri 18apr2025 PDT with an ADC timing error.

I am able to ssh onto the machine and first scans suggest we have lost an ADC in this system (only 7 of 8 are seen with lspci). We will need to power cycle the IO Chassis before deciding if an ADC replacement is needed.

This is an auxiliary SUS frontend for HAM2 meaning ADCs only and no control function has been lost.

Dmesg:

[Fri Apr 18 23:43:12 2025] rts_cpu_isolator: LIGO code is done, calling regular shutdown code
[Fri Apr 18 23:43:12 2025] h1iopsusauxh2: ERROR - An ADC timeout error has been detected, waiting for an exit signal.
[Fri Apr 18 23:43:12 2025] h1susauxh2: ERROR - An ADC timeout error has been detected, waiting for an exit signal.
 

S. Koehlenbeck, J. Freed, J. Kissel, J. Oberling, R. Short

The SPI pick-off path installation on the H1 PSL table is now complete. The beam in the new SPI path has been reduced to 20mW and is currently being dumped with a razor dump between SPI-L1 and SPI-L2. Pictures attached reflect the final installation and layout, which will be be reflected in the updated as-built layout at a later date.

Associated entries: 83925, 83933, 83956, 83961, 83978, 83983 (and more to come)

RyanC, Rahul

SUS Tip Tilt - RM1, RM2 and PM1 (picture attached) are now ready to be installed into HAM1, once the chamber is ready to accept them. The blade springs of all three suspensions have been un-muted and bosem connectors have kapton take inserted to prevent grounding issues. This morning we cleaned all three optics using First Contact - see picture for reference.

PM1 Beam Dump (rear)

Camilla, Betsy, RyanC, Rahul

SUS PM1 (Tip Tilt) has a new beam dump attached to it's rear - as shown in several pictures attached below. We had to design a new plate (D2500101_V1) to attach the beam dump. I can confirm that all the components integrates well with PM1 and there is some scope for adjustability as well.

Team SUS is now ready for HAM1 installation work.

S. Koehlenbeck, J. Freed, R. Short, J. Kissel

The mode matching of the PSL pick-off beam to the SPI fiber collimator has been implemented using two lenses. The target beam has a mode radius of 550 µm at a position 63.5 cm downstream from the SPI beamsplitter (SPI-BS).

The lens configuration that produced the closest match to the target mode used:

• L1: Focal length = 100 mm

• L2: Focal length = 60 mm

Attached is a beam profile fit performed using JaMMT on data acquired with a WinCamD of the beam after SPI-L2. The measured beam radii at various distances from the SPI-BS are as follows:

Both lenses are oriented such that their planar sides face the small beam waist between the two lenses. The arrows on the lens mounts point toward the convex surfaces.

The power transmission through the fiber has been measured to be 83 %.

J. Kissel scribing for S. Koehlenbeck, J. Oberling, R. Short, J. Freed
ECR E2400083
IIET 30642
WP 12453

Another quick summary aLOG at the end of the day, with more details to come:
- With the power in the ALS/SQZ pick-off path to 10 [mW] for beam profiling,
- Installed a two lens system to handle the unexpectedly different beam profile of the ALS/SQZ pick-off path
- Remeasured the resulting mode after the two lens system, and we're happy enough. We're gunna call them SPI-L1 and SPI-L2.
- Installed steering mirrors SPI-M1 and SPI-M2.
- Rotated ALS-HWP2 to increase the s-pol light in the ALS/SQZ/SPI path to return the power transmitted through SPI-BS1 going to the ALS/SQZ fiber collimator back to 50.5 [mW]. This set the SPI path to 186 [mW] with the PMC TRANS measured at 103.5 [W]. The ALS_EXTERNAL PD in transmission of ALS-M9 measured 31 [mW] ***. 
- Installed SPI-HWP1 and SPI-PBS01
- Measured the power at each port of SPI-PBS01, with the intent to optimize the SPI-HWP1 position to yield maximum p-pol transmission through SPI-PBS01.

*** We expect this is lower than the goal of ~45 [mW] (from LHO:83927) because we've not yet re-aligned the ALS/SQZ fiber collimator path after the install of the SPI-BS1, which translates the beam a bit due to the thickness of the beam splitter. We intend to get back to this once we're happy with the SPI path.

J. Kissel scribing for S. Koehlenbeck, R. Short, J. Oberling, and J. Freed
ECR E2400083
IIET 30642
WP 12453

During yesterday's initial work installing the SPI pick-off path (LHO:83933), the first optic placed was SPI-BS1, the 80R/20T power beam-splitter that reflects most of the s-pol light towards the new SPI path. The pick-off is to eventually be sent into a SuK fiber collimator (60FC-SF-4-A6.2S-03), so we wanted to validate the beam profile / mode shape of this reflected beam.


The without changing any power in the ALS/SQZ/SPI pick-off path, the power now reflected from newly installed SPI-BS1 measured ~40 [mW] (see LHO:83946). This is too much for the WinCam beam profiler, so they used ALS-HWP2 to rotate the polarization going into ALS-PBS01, and thus reduced the reflected s-pol light in this ALS/SQZ/SPI pick-off path to ~10 [mW]. That necessarily means there's a little more of the ~2 [W] p-pol light transmitted and going toward the HAM1 light pipe, so they placed a temporary beam dump after ALS-M2 so as to not have to think about it.

The they set up a WinCam head on a rail and gathered the beam profile. With the WinCam analysis software on a computer stuck in the PSL, they simply gathered the profile information which I report here: 
# Distance[cm]	Radius[um]   Radius[um]
                   X             Y
    0.0           680.5         717
    17.78         465           504
    25.4          389           428.5
    30.48         346.5         368
    38.1          281.5         300.5

where "X" is parallel to the table, and "Y" is orthogonal to the table. The "0.0" position in this measurement is the "front" of the rail (the right most position as pictured in the attachment), which is Column 159 of the PSL grid. SPI-BS1 has the center of its reflective surface is set in +/- X position in Column 149 (within the existing ALS-PBS01 to ALS-M9 beam line). It's +/- Y position is set to create a reflected beam line along Row 30 of the grid, and the WinCam head and rail are centered in +/- Y on that Row to capture that beam.

Using this profile measurement, we find it to be quite different than expected from when this path was installed circa 2019 (see e.g. LHO:52381, LHO:52292, LHO:51610). Jason shared his mode matching solution from LHO:52292 with us prior to this week, and I've posted it as a comment to that aLOG, see LHO:83957.

We think we can trace the issue down to an error in the as-build drawing for the PSL:
- the whole beam path running in the +/-X direction from ALS-M1 to ALS-M2 is diagrammed to be on row 23 -- however, we find in reality, the path lies on row 25. That's 2 inches more between the (unlabeld) pick-off beam splitter just prior to ALS-M1 and ALS-M1 itself. Easily enough to distort a mode matching simulation.
- Jason confirms that he used the *drawing* to design the lens telescope for this ALS/SQZ fiber distribution pick-off path.

More on this as we work through a lens solution for the SPI path.

As of this entry, we elect to NOT create a new solution for the whole ALS/SQZ fiber distribution pick-off i.e. we *won't* adjust ALS-L1 or ALS-L5 in order to fix the true problem. But, we report what we found in the event that a case is better made to help mode matching and aligning into the ALS/SQZ fiber distribution pick-off easier -- as we have verbal confirmation that it was quite a pain.
For the record the fiber collimator used in the ALS/SQZ distribution pick-off is a Thor Labs F220 APC-1064.