I've moved PR3 back to latter half of O4 based on the slider, not OSEM.

Assuming that the ITMX angle is good and the beam deflection angle through the BS is the same as before, the plan to get ready for the arm peeking is as follows.

Find a good IM4 angle where the ITMX reflection comes back to ISCT1 camera (Louis is working on it).

Once that's found, align PRM, refine PRM and IM4 alignment to have a good PRX flash.

After that we might have to walk the beam on PR2 without touching ITMX and PR3. Unless there's a convenient script to do that, you'll move IM4 a bit, change PR2 so that ITMX retro reflects, and change PRM to recover PRX.

By iterating, you'll eventually settle on the beam position on PR2 that will give you an ok signal on LSC or ASC (hopefully both) POP sensors in HAM1. 

Also work on the ISCT1 alignment for the ALS beam, but this will be on Monday.

WP13495

The following supplies were replaced in the CER Mezanine.

Kepco Power Supply in VDD-C6 Rack, Left Slot U31-29, ISC-R3&R5 +24V
Old S12001945
New S12001992

Kepco Power Supply in VDD-C6 Rack, Right Slot U31-29, ISC-R3&R5 -24V
Old S1201946
New S1201947

The negative supply was oscillating between 22V and 21V when measured before replacing, possibly due to failed fan.  New supplies were adjusted to +/-24V at the racks.

Caroline C, Marc P.

This morning JAC lost lock due to temperature drift (temperature control was on) and at the same time WFS went crazy. After that JACK_LOCK guardian couldn't lock it, just kept scanning without success because the alignment was very much off.

When this happens, what you should do is:

• Move JAC_LOCK to DOWN.
• Open JAC_WFS_MASTER medm screen and clear history for DOF1_P and DOF1_Y.  JAC_WFS_crazy.png
• From that screen, open JM1 screen and you'll see that the LOCK_P and/or LOCK_Y output are big, like (JAC_WFS_crazy_JM1.png). Click "Lock Filters" and clear the history of P and Y.
• Move JAC_LOCK to LOCKED.

For the lockloss and WFS behavior see jac_lockloss.png.

 JAC lock voltage was drifting lower and lower, which meant that you must have cooled JAC down, but the temperature servo was heating it more. Ultimately we need a temperature servo to keep the lock PZT voltage constant rather than keeping the temperature sensed by the thermistor.

After the lock voltage alredy hit the bottom rail, it took about a minute for JAC to completely lose it. During this time, JAC_L error increased as the JAC slowly became off-resonant, and of course the same signal is seen by all WFS segments. Since WFS centering is not perfect, this increased WFS P and Y signal. JAC ASC tried to counter this by twisting JM1 and the PZT mirror without success.

Finally the WFS was turned off but mirrors were already heavily misaligned at that point. 

RGA scans were collected for the corner volume using the new PrismaPro RGA. This RGA tree had been rebuilt and baked at high temp for 2+ weeks. Scan info below, raw data files will be posted to the DCC at T2600329.

RGA Model: Pfeiffer Prisma Pro

EM Voltage: 1200V

Dwell Time: 1s, 0-100 AMU, 10 pts/AMU

Valve States: GV5 & GV7 closed, FC2 & FC4 closed (Relay Tube removed & FCB-1 section common with corner)

Pumping: 3x 2000 l/s Turbo pumps, 1x 500 l/s turbopump (HAM6)

RGA filament has been on since 7/22 after RGA tree bakeout

Corner Pressure (8/7/26): 3.2E-7 Torr (PT120B)

Corner Pressure (7/27/26): 5.3E-7 Torr (PT120B)

Comparison plot showing partial pressure decrease after an additional ~10 days of pumping with turbo. Corner started high vacuum pumping on July 16th 2026 (22 days of pumping with turbopumps only)

Dave, Erik, Claude

Claude AI wrote a python script to plot the H1 DAQ CRC rates for the past 6 months for all frontend and both DAQ legs (see attached). This plot only shows when an individual DAQ leg recorded a CRC error from the front end. The times there were CRCs on both legs were usually due to model restarts and not spontaneous errors, so these have been removed from the plot.

The vertial lines align with Tuesdays and possible maintenance activities.

General first thoughts are: over the long term the CRCs are fairly randomly distributed over front ends and DAQ legs; in the past week they have been concentrated on the 0leg and the two frontends iscey, seib1.

TITLE: 08/07 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: CALM
    Wind: 3mph Gusts, 1mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.06 μm/s 
QUICK SUMMARY:

I came in this morning to a Vacuum Alarm on H0:VAC-EX_X2_PT524_PRESS_TORR. Wait! Dont panic! Vac Team had already put in an alog about it. 
Other than that Every thing looks good.... EXCEPT:  the RMS 1 & 2 are saturating for some reason. Tagging SUS
This started to happen at a round 7  UTC .  I took those Suspensions to Safe.

Found PT524B cold cathode gauge tripped/off, turned it back on, now we wait for it to comeback.  Gauge was tripped yesterday around 23:49 utc.

This alog was intended to be a comment on 91436

This morning we continued to use the crane that Camilla and Ryan devised to try to get more reliable power budgeting measurements on the VIP.  Our previous measurements with the power meter held in a hand and hovering over the table consistently showed that we have something like 4% extra losses in HAM7, but they have not been repeatable enough for us to track down the location of the losses.  The crane set up helps us set the angle of the beam profiler head by using a clamp on the post, and also gives us much more steady measurements of power, so we were able to make some progress in identifying the location of losses.  However, we think that the power out of the OPO was drifting by 1-2% during these measurements, which makes the measurements less reliable for finding losses.  

We do think that we have about 0..8% loss at B:L2, where the difficult to align apperture stop is.  This apperture stop catches a rejected beam from B:P1 which is scattered light from the interferometer, so we need to keep it.  We looked for space to move it off the lens mount onto it's own separate mount, but the platform is very crowded with bases and dog clamps in this area, so that would not be an easy solution.  

For the naming of optics see:  D2000021

• (location A) after SFI1 return (before BM1): 1.251mW. (readjusted crane and centering of beam on power meter)
• (same location as A) Moving FC1 and watching SFI1 Return power. Starting P 225, Y -156 (We do not see obvious evidence of clipping in SFI1 on the return path in this data).  
  • 205 Pitch  1.247mW, STD dev 0.59uW
  • 225urad Pitch   1.247mW, STD dev 0.51uW
  • 245urad Pitch   1.247mW, STD dev 0.88uW
  • -156urad Yaw 1.246mW, STD 0.66uW
  • -136urad Yaw 1.246mW, STD 0.57uW
  • -176urad Yaw 1.243mW, STD 0.54uW
  • Starting 1.246mW, STD 0.5uW
• (location B) between SFI1 polarizer and rotator (on way to FC): mean 1.315mW std: 0.41uW.  Comparing this to above numbers it implies we have a loss of 4.9%, 5.2%, or 3.4% using number below, where we expect 2%
  • We decided to measure here instead of right out of the OPO because we were concerned that the slight angle of the beam coming out of the OPO might have been making it hard for us to put the power meter head perpendicular to the beam, and it was easier to get the angle right in this location.  In the end we got similar powers and loss estimates measuring here as measuring right out of the OPO.
• (same location as A) after A:P1 : 1.269mW STD dev 1.4uW; unlocked reloacked OPO retook to be 1.270mW STDdev 2.3uW;  1.270mW STDdev 1.7uW. Implies loss of 3.5% where we expect 2%
• (location C) after B:L1: 1.260mW std 2.1uW  1.259mW std 1.5uW 1.258mW 1.8uW 1.260mW 1.2uW Implies 0.8% loss from B:L2, probably clipping on apperture stop.
• (repeat of location B) back to between SFI1 polarizer and rotator (on way to FC) 1.330mW std 0.66uW 1.329mW std 0.67uW 1.329mW std 0.46uW  Power must have drifted up 1% since our first measurement here.
• after SFI1 before A:L2 : 1.327mW std 0.91uW  1.328mW .66uW 1.326mW 0.80uW 1.324mW std 1.1uW This implies very low loss from SFI1's rotator and 2nd polarizer, although it is possible that the rejected beam from A:P2 could also be on the power meter in this location, we could not identify that beam on a card. If the apparent loss of about 1% from each pass of SFI1 is really from misrotation the rejected beams would contain about 10uW, which we could search for more thourughly with the lights off using an IR card with a viewer.  
• after A:M3 1.321mW std 0.37uW; 1.321mW std 0.52uW; 1.320mW std 0.6uW; 1.320mW std  0.5uW Implies 0.5% loss probably at the aperture stop attached to A:L2.  
• back to after SFI1 before A:L2: 1.305 std 0.7 1.305 mW std 0.7uW 1.316mW Power is drifting enough to make these measurements confusing. 

The UPS for the EY Access system that powers the network switch a camera failed this afternoon. Power to the cameras and switch was bypassed for now.

Sheila, Ryan S, Camilla, Rahul

This morning Fil and Rahul go the ZM5 chassis working, 91431. Ryan checked the Strain gauge resistors didn't need adjusting after ZM4 preload adjustment 91416.  This afternoon we used the iris at ZM5 and irises on SQZT7 to realign ZM4 and ZM5 after this chassis swap and ZM4 offload. New ZM4 ans ZM5 settings: attached.

This morning Sheila and I checked more power budgets using craning over the OPOS. Sheila has the numbers but we convinced ourselves that the aperture at A:L2 is causing us to lose up to 2% power. But the aperture at B:L1 we are not clipping as we could not increase the power through it by moving FC1 (stepped ~20urad and then took the mean of 10s of data on the Thorlabs power meter).

TITLE: 08/06 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY: Input alignment work in the morning, then the LVEA was transitioned to laser safe for some vacuum work on GV6. HAM7 crew got closer to closeout today.
LOG:

• 1450  VAC gauge PT180 tripped off.

Started going through the list of tests from G2601523 to find/reduce the CRS noise.

Dark test (i.e. turning off the CRS laser)

• Added offsets matching the raw PD inputs when the laser was on (1S: -1307, 1C: -374.22, 1M: -2813.2, 2S: -1243.43, 2C: -2309, 2M: -113.725) in order to make sure the atan function gave back real data.
• The laser was off and the offsets were added at 10:35 PST (1470072968.0) 
• Took about 1 hour of data for spectra
• From my understanding, it looks like the dark noise/ADC might be limiting at the higher frequencies (>5Hz), but doesn't really account for much below ~5Hz. (Spectra attached, purple and oragne is dark, blue+green reference)
• dtt template saved in /ligo/svncommon/SeiSVN/seismic/HAM-ISI/H1/HAM3/CRS/Templates/dtt/CRS_HoQI_Dark_spectra_26-8-06.xml

Unplug HoQIs to get ADC Noise

• Unplugged HoQI's from pre-amp, kept same offsets from dark test (above) at 11:46 PST (1470077241.5) 
• Similar results as with the laser turned off (Spectra attached, red and black line is unplugged)
• dtt template saved in /ligo/svncommon/SeiSVN/seismic/HAM-ISI/H1/HAM3/CRS/Templates/dtt/CRS_HoQI_Unplugged_spectra_26-8-06.xml

Next steps are to add some copper on top of the laser to see if that reduces the noise, and then looking at the impact of the motion of the out of vacuum fiber once the LVEA is safe. The HoQI's will be re-connected to the pre-amp and laser turned back on so Jim can take some more transfer functions.

Fil and Oli had already done this work yesterday, but Oli's result (posted in alog 91411) indicated that something was not right with ZM5 CD chassis. 

This morning Fil and I replaced it with the original chassis (was earlier used for ZM5 with 1.2kohm resistor) - however, Fil installed 100 Ohm resistors on this. 

Attached below are the screenshots for ZM5 L, P and Y dof. and they looks healthy - magnitude and peaks are in their place. 

ZM5 chassis installed today - D1100687, SN  S1200611 

Outgoing chassis - D1100687, S2001198

This has been wrong for forever, I fixed it at one point a long long time ago (alog 29798) but apparently didn't put it in SDF.

Anyway, FM4 of H1:PSL-ISS_SECONDLOOP_QPD_SEG filters named 0.4:40 was OFF, it should be ON all the time like in the attached screenshot.  When it's wrong the signal looks noisier than it actually is and is annoying even though it's not used for control and doesn't matter during observing.

I accepted the change in the SDF.

I changed the heater power from 0.8 to 2W, and the temperature increased up to ~25.4 degrees. The heater guardian setpoint was also changed to 25.41, and engaged at 9:07AM. 

Jenne, Wanda, Shoshana, Gizem

We started very early this morning to beat the heat, and performed 'tap tests' at various points along the length of the arms to identify positions along the length of the fiber (according to DAS) with GPS positions (according to Wanda's phone).

Spreadsheet attachment is information about where along the fiber Shoshana and Gizem identified our tapping in the data, and associated time stamps.  I've also copied the spreadsheet data to a google sheet, so that we can add to it.  

We tried to do more dense taps on the 'inside of the vertex' side of the arms, where the fiber actually is.  This required some walking out in the sand along the arms, so we had sun hats and knee-high boots and plenty of water.   We also did a few taps along the road during our drive back, to get some more coarse information along the length of the arms.  At the Xend station, there were too many tumbleweeds for us to walk along the inside-vertex side of the arm, so there at EX we did our more dense taps along the road side, with the exception of the EX vault location. 

In the attached photos, you can see some examples of our tap test method.  Gerardo provided us with a scrap piece of steel that we used as a strike plate.  We also borrowed a sledgehammer from the mechanical / vacuum parts lab.  For most of the Yarm, we only did 3 heavy strikes and Gizem and Shoshana chose the strongest signal from that as our time.  Once we were on the road-side of Yarm, and then for all of Xarm, we added some light tapping that seems to have helped identify which distance bin (called a "channel" in DAS terminology) we were closest to.  The photos are also labeled with X/Yarm, and position number, which corresponds to the position numbers in the google sheet - I tried to capture features in the photo to help identify where exactly the strike plate was.

Wanda has added to the google sheet the GPS locations that she identified while we were at each tap point.

The last photo shows our used (but can be used again in the future!) strike plate. 

Travis, Gerardo, Jordan

During the closing of GV6 back in May, we noticed that there was some blow-by in the pneumatic system when trying to hard close the valve, see alog 90093. 

We were able to hard close the valve eventually but as preventative maintenance we wanted to replace the air cylinder seals, similar to GV7.

Prior to disassembly we measured the locations of the reed switches from the top surface of the bottom plate to the bottom surface of the reed switches:

Bottom Switch: 1 1/8"

Top Switch: 49 1/4"

We then disassembled the air cylinder and replaced the seals following procedure/notes collected during the GV7 repair. During cleaning of the old grease on the piston head, we noticed there were two burrs on the top of the piston, we did not notice any damage to the inside of the cylinder, but as a precaution we used a small flat file to remove the burrs. We also chased the threads on the four threaded rods with a die to aid with reinstallation. After cleaning and inspection of the cylinder tube, we found no issues or damage so we decided to continue to use that cylinder and keep the new one as a spare.

No other issues encountered, we removed the old seals, cleaned the grooves, added copious amounts of the supplied grease to the o-rings, seals and the inside of the air cylinder, and then re-assembled the cylinder tube. Pictures posted below and a final procedure is in progress and will be posted to the DCC.

We did not get a chance to cycle the valve after the seal replacement, so we will continue tomorrow with cycling the valve.

(Jordan, Travis, Gerardo)
We removed and replaced the AIP for BSC6, no real complications while doing the work.  However the joint at the AIP and the isolation valve has a tiny gap towards the bottom, we started pumping down on the system and it appears to be a solid union, we will go and visit tomorrow and see how the pressure is doing.  On a side note we did find a flex metal hose that has a leak, it has been removed from circulation.

Summary

Whatever happened to IM1, Rahul did make it better again. Reasons for improvement is unknown but we proceeded with the alignment and we're mostly done.

There is a mystery scattering or maybe clipping somewhere close to the IFI output but not on the output baffle nor DKDP baffle. It could be a scatter from the CWP surface, or a ghost beam somewhere, or something else. It will take a LONG time to diagnose this, and quite likely this existed for a long time. I'm tempted to leave it at this time. But I'll try to take some more pictures.

There's also something weird about the 1st pico mirror PIT actuator for ISS array.

We'd still like to take pictures/measurements here and there on Tuesday.

Done: ASC REFL centering

Following the morning work (alog 90525), REFL ASC censors were centered using RM1 and RM2. About ~30% of DAC range was used for RM2 (RMs_happy_again.png). FYI, using flash peak, [P,Y]=[-0.003, 0.015] for REFL_A and [-0.020, 0.001] for REFL_B. (Doesn't matter how close these are to zero as far as they're within +-0.1 or so and the SUM is decent, but it feels better to be able to get close to zero.)

Done: ISS array centering

Then we looked at the ISS array and the QPD was not centered. A quick adjustment of the second pico that is closer to the array was all it needed (keita_ISS_happy1.png). [P, Y]=[-0.03, 0.05].

Done: IFO REFL baffle (HA13) adjustment

We looked at the IFO REFL baffle (HA13) in front of the HAM2-HAM3 septum window and it was too high even though it was not clipping, so we lowered it by a couple mm. Before: lower edge height = 105.5mm; upper edge = 206.8mm. After: lower edge = 103.6mm; upper edge = 204.5mm.

This baffle was already moved by a couple mm in +Y direction last week (because the beam was closer to +Y edge). See  IFOREFL_baffle_before_relocation.jpg and IFOREFL_baffle_after_relocation.jpg though it might be difficult to see the difference from this picture.

IFO REFL beam looked like IFOREFL_HA13_baffle_after.mov after the height adjustment.

Mystery flashes seen inside IFI output baffle aperture

We proceeded to check the IFI output baffle and I was bothered to find that something that looked like clipping was visible close to the left edge of the baffle using the IR camera. See IFI_OUT_clipped_720p.mov, this is a view from +Y door. But this was less frequent than the flashing itself. In a retrospect, this was probably the reflection from the PRM when the beam was swinging to the left of the video, but anyway we did various things:   

• We got suspicious about PRM somehow misaligned, checked it on the retroreflection check iris but it was fine in YAW (it was off in PIT so changed PIT offset from -1185 to -1115, not sure if it was PRM that changed or something else, but the important thing was that it wasn't off in YAW and that this is not something that I worry about now that we have a decent headroom for RM2 DAC).
• We closed the HAM3 door cover (which did quiet down the beam motion a lot) as well as the HAM2 -Y door cover. I used IR viewer and thought that nothing changed at the time. The bright thing didn't disappear after blocking the beam between PRM and IM4, again using the IR viewer, I thought.
• However, revieweing videos shot later, I haven't found anything to the left of the output baffle after the beam motion was reduced by closing unnecessary open door covers. But that revealed the next issue.

See IFI_out_another_view.mov, this is after the beam quieted down enough and after PRM PIT was changed. The bright thing at the left side of the baffle hole is not visible any more, but you can still see bright-ish scattering of some sort inside the baffle aperture which was there even when Rahul blocked the beam between PRM and IM4. IFI_out_another_view.jpg shows the same thing but with more useful exposure. This is concerning.

DKDP baffle behind the IFI output cwp baffle looked OK (IFI_DKDP_baffle.mp4). BTW, as was reported before, it looked to us that the IFI output baffle has an offset in -X+Y direction relative to DKDP. In the video, the beam on DKDP is slightly biased to the right on average because we tried to split the difference between two baffles.

We moved IM1 in YAW by +-200urad while observing the IFI output by IR viewer to see if there is a better beam position on IFI output. It seemed to me that actually we don't have much space here.

Look at IFI.png to see how the beam is routed through DKDP, output CWP and then passes by the parking beam dump pick-off.   

• If we give negative 200urad for IM1 YAW, the forward-going beam starts to interfere with the parking beam dump pick-off once in a while and the frosted barrel of that pick-off becomes bright. This is despite that the beam looks perfectly fine when IM1 is at the now-nominal position (see parkingBD_pickoff.mov, negative 200urad IM1 rotation would mean that the beam will be like 1mm to the right in this video).
• If we give positive 200urad for IM1 YAW, I thought that +X side of the IFI output cwp baffle starts to get brighter once in a while (my theory is that this is the same thing as shown in IFI_OUT_clipped_720p.mov where the edge of the baffle clips the back-propagating beam when the beam moves too much).

We'll be better once we're in vacuum because things will be quieter and the MC alignment will be better, so no beam motion and no HOM transmission, but I have to say that the clearance here looks to be unnecessarily narrow. I will NOT touch IFI itself so the only option for mitigation will be to move the parking BD pickoff, but it will be tedious to align that pickoff to steer the beam into the beam dump on top of HAM2. Given the limited time available I'll leave it as is.

We don't know what this scattering is, maybe it's the AR reflection of CWP or DKDP hitting something, maybe it's the surface scatter of CWP. I'll try to take the video from the back of the IFI output beamdump/CWP using a big inspection mirror.

Done: IM4 TRANS centering.

Rahul used pico mirror to roughly center IM4 TRANS while I was monitoring individual segments. IM4TRANS_ROUGHLY_BALANCED.png

Done: IM4 baffle (HA12) moved

As planned. The beam originally was offset in +X direction (IM4_HA12_before.jpeg shows the original location, IM4_baffle_HA12_before.mov shows the beam position), IM4 baffle was moved a bit in -X direction (IM4_HA12_after.jpg, IM4_baffle_HA12_after.mov).

Done but not really: Picturing the picos, one concern for the first ISS pico actuator.