I turned off thew JAC heater guardian at 17:42:00 UTC.

Then I applied a 0.2 V voltage offset to the error point to measure the step response.

TITLE: 09/17 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: 10mph Gusts, 7mph 3min avg
    Primary useism: 1.12 μm/s
    Secondary useism: 1.71 μm/s 
QUICK SUMMARY:

• We're getting hit by a 6.4 from the Aleutian islands
• The LVEA is in HAZARD as of now, we will go SAFE for some work, VP installs, SEI CPS cabling, crane repair...
  • BSC8 between GV 1 & 5 was vented yesterday, BSC7 between 2 & 7 still needs to be vented
• Temps look stable (EX calmed down), no dust alarms
• EX vacuum pressure is at ~3e-6

(This is the alog for measurement proceeded at beginning of August)

Summary

We measured JAC's LSC in-loop error signal (JAC-L_SERVO_IN1) across the 2–62 W power sweep, calibrated each dataset from its own 30 Hz line, and built a residual length-noise budget (in-loop residual, sensor floor, shot floor). IMC locking reduces the equivalent laser-frequency noise by ~1.9× over 7.5–76.7 Hz (peak ~2.6× near 12 Hz); above ~30 Hz the residual is sensing-floor-limited. This budget is the input to the excess intensity- and frequency-noise coupling estimates.

Measurement

• Data:, 2 / 35 / 62 W input (plus an unlocked set), each carrying a 30 Hz JAC-L_SERVO_EXC calibration line.
• Error signal: JAC-L_SERVO_IN1
• Main comparison: 35 W IMC-on vs 62 W IMC-off — both high-power, single-FSS-stage, each with its own directly measured optical gain.

Analysis

• Open-loop gain G = A·F·H. A (actuator) and F (servo filter) imported from the OLG fit and treated as power-invariant.
• Optical plant H(f) = optical_gain / (1 + if/f_pole), with optical_gain measured fresh per dataset from its own 30 Hz line. f_pole ≈ 593.9 kHz (ring-cavity FSR).
• A is found in alog 89399
• Free-run length noise: L_free = (IN1)·|1−G|/|H|.
• In-loop residual (closed-loop, as sensed): (IN1)/|H|
• Sensor floor: current-configuration dark reference, re-scaled per dataset by PSL power and |H|. Shot floor: sqrt(2·e·I_dc), I_dc = R_PD·P_refl from each dataset's own REFL DC.
• Total residual: sqrt(in-loop² + sensor² + shot²).
• Frequency-noise equivalent: δν = L_free·ν/L_cav (ν = c/1064 nm, L_cav = 2.02 m).

Result

• IMC on vs off: reduction of ~1.9× over 7.5–76.7 Hz (peak ~2.6× near 12 Hz), extracted data-driven from R(f) = off/on (log-frequency rolling median, threshold 1.3), not an assumed band.
• Residual budget: above ~30 Hz the in-loop residual sits at the sensor / shot floor (sensing-floor-limited); below that it is above the floors.
• OOL cross-check: the WFS SUM_A out-of-loop sensor, calibrated in situ from the same 30 Hz line, was used to cross-check the residual errors. At low frequencyes, it has a higher sensor noise then residual, and it can't be good sensor for those frequencies

Next

• This residual budget (m/√Hz, per dataset) is the direct input to the excess intensity-noise (RIN) and phase/frequency-noise coupling estimates for JAC.

Figure: free-run length noise with the sensor noise

Figure: residual noise budget — in-loop residual, sensor floor, shot floor, and their quadrature sum

Figure: equivalent laser-frequency noise, IMC on vs off,

The temperature changes at EX due to the vent and FAC controls adjustment had pushed BRSX out of range. This afternoon, I used the picomotor in the BRSX can to recenter, by going to LSC->Picomotors->ENDX. I set the channel to 5, enabled the driver and waited for the driver to finish enabling. I then moved the motor 5000 steps positive, from -2250 to +2750, then moved the motor -1000 steps to disengage the mass adjuster, so final pico position is 1750 steps. This moved the driftmon channel from the max negative value -16k to around +9k, so the total move of the spot was more than 25k "cts". I have changed the heater voltage from 3v to 5v, which should move driftmon a bit closer to center. After making the move, I attempted to log into the beckhoff machine and got some error about "received certificate is not trusted".  This was eventually resolved, but Erik had to restart the Beckhoff machine to fix it, so the PLC, BRS C code and epics IOC needed to be restarted. Everything looks good for now, heat is moving driftmon in the right direction, brs is damped down after the pico move. I will check again tomorrow morning.

(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.

We noticed this today while debugging alignment issues. I compared the powers for 10 W request from PSL.

All of sensors beyond the JAC agree that there is 4-5% less power now making it to the IMC.

While at 10W input to JAC and commissioners working on IFO alignment this afternoon, we noticed the output power of JAC and the IMC start to gradually drop until finally JAC unlocked. Anecdotally, some of us have seen this happen at random times before, and JAC has always relocked easily pretty much immediately afterwords, so we haven't given it much thought, but it would be great if JAC didn't do this. I trended several things and can't tell what exactly happened first to cause this, but clearly the length servo and ASC outputs started changing dramatically over about 15 seconds until the cavity unlocked. I've attached short-term and long-term trends leading up to this unlock. I don't have a proposed solution, but mostly wanted to document this happening.

TITLE: 09/16 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: None
SHIFT SUMMARY: EX is now pumping down, GVs 1, 2, 5, and 7 are closed and the RCG upgrade was completed.
LOG:                                                  

• 16:30 UTC Erik started the RCG upgrade after I put SUS and SEI into their safe states
• ~18:35 UTC I recovered the CS, ~18:45 I recovered the end stations
• 19:15 UTC The SUS slider scopes were unfortunately not SDFed yesterday so Oli, Elenna, Caroline and I brought them back based on top mass osems and OPLEVs when available
• 21:30 UTC Gate Valves 1 & 5, and 2 & 7 were closed
• CDS overview still shows some channel disconnects related to the EX BRS.

Ryan Short, Sheila Dwyer, Alex Granados

We went to SQZT0 to check on the low green launch powers.  We need to realign the AOMs in both the OPO pump and FCGS paths. 

• SHG power reported by medm: 109 mW
• measured with power meter: 84mW before green pump EOM
• measured with power meter between EOM and AOM: 88 mW
• 0V on AOM, 23mW measured after
• FCGS path: 24mW before 1st AOM, 8 mW after 2nd AOM

We need to realign these AOMs in laser hazard, but couldn't find a nice power meter mount.  We will come back to this when back in laser hazard.  

h1brsex could not be reached through remotedesktop.  Locally, the computer was at the windows log in screen, but when I attempted to log in, the computer got to a loading screen and never got past that point. 

I did a gold boot of h1brsex.  It spent a long time on a screen saying it was "configuring windows", something that usually only shows up when you log in for the first time.  After that boot, remote desktop worked.  The epics IOC did not autostart and still needs to be started by hand.

Jonathan, Fil,

Per work permit 13583 we replaced sw-lvea-aux with sw-lvea-aux2.  This is the camera that provides power and network for most of the cameras in the LVEA.  In addition it handles some of the access points.  We had seen two failures in the switch.

In order to replace the switch we needed to disconnect connections to both sw-lvea-aux and sw-lvea-aux1.  Interestingly enough we had problems with the cameras on sw-lvea-aux1 after this.  At around 3:00pm localtime Jonathan power cycled sw-lvea-aux1 and the cameras were restored.

WP13620 RCG Upgrade

Jonathan, Ryan C, Fil, EJ, Erik, Dave

This morning we successfully upgraded all the front ends from RCG5.6.5 to RCG5.6.6. This required rebooting all the front end computers, plus the two diskless support machines (h1build, h1ecatmon0).

The main reason for the upgrade was to fix the DAC-Flips-Output-Polarity-At-2-Billion-Counts bug, which has been seen as recently as this weekend on H1 SUS systems driving LIGO-DACs (though the bug applies to all types of DACs).

Other fixes are with mixed DAC type mis-mapping, which required LIGO-DACs to follow Gen Std cards on the bus. Also RCG5.6.6 provides full LIGO-ADC support.

We took the opportunity to verify BIOS settings as part of rebooting the front ends. We also disconnected unused Adnacos from the host adapter cards (i.e. Adnaco backplanes with no cards installed on them).

This all went relatively smoothly, with the only surprise being EDC flapping on its DAQ connections on both legs. Erik remembered that a negative wait time is needed, which fixed the issue.

Before today h1omcpi was running a custom RCG to add an IPC delay for the channels it receives from h1ioplsc0. It no longer needs a custom RCG, the new RCG5.6.6 has provision to set the delay via a file.

At the end of the build/install pre-upgrade work done yesterday (Tue 15sep2026) h1crsproc and h1psliss were falsely reporting modifed INI files. We verified these were false and the ini files were byte identical. These was borne out after the reboots, no DAQ restart was required for any of today's work.

WP13610 Enable PERR/SERR Reporting In BIOS

All front ends now have PERR/SERR PCI bus error reporting where applicable (V4, W22 have these option, W33 do not, we assume it is the default here)

We also verified the BIOS setting to keep the machines powered down following a power distruption when power is returned. This prevents front ends from trying to boot prematurely.

WP13606 Disconnect Unused Adnacos

All done with the exeption of h1susauxex A4.

WP13609 h1oaf0 Adnaco investigation

Erik found the adnaco fibers were dirty and cleaned them. We are waiting to see if this has improved the error rate.

Jennie W, Fil C, Marc P,

To hopefully fix the intermittent noise on the SPI optical lever QPDs (see alog #91813), Marc and I pulled the ground pin (13) at the input to TIA chassis variant 2 in SUS-R3 rack and variant 1 in SUS-R2 rack, respectively. When the RCG upgrade is over I will run some dark noise measurements to check this noise is gone.

At 09:30 we started the RCG upgrade. All front ends are currently unavailable.

No DAQ restart is anticipated. The EDC was offline for about 20 minutes and is now back up and running.