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Reports until 08:57, Friday 14 August 2026
H1 CDS (DetChar, PEM)
david.barker@LIGO.ORG - posted 08:57, Friday 14 August 2026 (91537)
Corner Station PEM Accelerometer mismatch identified and fixed

Miranda, Dave:

Over the past week we have documented the LHO PEM accelerometers and produced an as-built  wiring drawing

This was in response to a possible misreading of accelerometer(s) with the wrong channel names.

We found three accelerometers with incorrect names, which date back to pre-O4, so I'm tagging DETCHAR.

The accelerometer Was being readout as this channel
H1:PEM-CS_ACC_LVEAFLOOR_HAM6_Z_DQ H1:PEM-CS_ACC_BEAMTUBE_SRTUBE_X_DQ
H1:PEM-CS_ACC_BEAMTUBE_SRTUBE_X_DQ H1:PEM-CS_ACC_EBAY_FLOOR_Z_DQ
H1:PEM-CS_ACC_EBAY_FLOOR_Z_DQ H1:PEM-CS_ACC_LVEAFLOOR_HAM6_Z_DQ

We fixed this at 16:00 Thursday 13th August 2026 PDT by remapping the BNC connections on the front panel of APC1. The cable going to port12 was moved to port13, that going to port13 was moved to port14 and that going to port14 was moved to port12.

We tap-tested the EBAY_FLOOR accelerometer at 16:10 and this showed up on H1:PEM-CS_ACC_EBAY_FLOOR_Z_DQ

H1 CDS
david.barker@LIGO.ORG - posted 08:44, Friday 14 August 2026 (91536)
new h1spih23 model and DAQ restart

We installed Jennie's new h1spih23 model (removed parts) which required a DAQ restart. Model was restarted at 08:02 and the DAQ restart between 08:04 and 08:20.

H1 General
ryan.crouch@LIGO.ORG - posted 07:34, Friday 14 August 2026 - last comment - 09:06, Friday 14 August 2026(91535)
OPS Friday Day shift start

TITLE: 08/14 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: 8mph Gusts, 6mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.12 μm/s 
QUICK SUMMARY:

Comments related to this report
ryan.crouch@LIGO.ORG - 09:06, Friday 14 August 2026 (91539)SUS

I took undamped TFs of PR2 this morning, the P and Y magnitudes seem a little higher than expected. I'm going to measure the OLG for P and Y next.

Non-image files attached to this comment
LHO VE (VE)
gerardo.moreno@LIGO.ORG - posted 01:47, Friday 14 August 2026 (91534)
Installation of HAM7 Doors

(Randy, Travis, Gerardo)
Today we installed two doors on HAM7, -Y door and +X door (flat door). Nothing to report with respect to the installation since no issues were encountered during process. Both doors were torqued.  Currently the annulus system is being pumped down with an aux-cart and a small can turbo, at end of the day the pressure at the aux-cart was reading 8.8X10-05 Torr. A very "wet" system and it shows on the pumpdown.

A side note for future +X door installation, use a bigger shackle on the -Y pick point, since the door needs a little rotation. 

Images attached to this report
H1 IOO
masayuki.nakano@LIGO.ORG - posted 21:31, Thursday 13 August 2026 (91526)
JAC WFS calibration, part 1: DC

The JAC WFS DC signals were calibrated. The motivation for this measurement is to check that the optical layout model is right. With JAC unlocked the beam in reflection is close to a pure TEM00, and the DC quadrant signals calibrate easily by normalising with the beam size. That makes the unlocked DC a clean sanity check on the layout and on the calculation built from it.


What was done

  1. Unlock JAC.
  2. Centre the WFS A and WFS B DC signals using the picomotors.
  3. Two independent excitations:
    • (i) calibration lines. Four lines, one on each actuator (JM1 PIT 9.7 Hz, JM1 YAW 11.3 Hz, PZT PIT 13.1 Hz, PZT YAW 14.9 Hz), driven simultaneously; the peak height was read out at each WFS DC.
    • (ii) broadband. White noise below 10 Hz injected into one actuator at a time, and the transfer function to each WFS DC measured.

What is predicted

The TEM10/TEM01 that each actuator generates is known in magnitude and phase from the actuator calibration and the layout model. At the WFS, these have rotated away from TEM00 by the accumulated Gouy phase between the actuator and the sensor. A DC quadrant photodiode reads the real part of the first-order mode amplitude at its own plane (more precisely, the real part of the odd modes), so the accumulated Gouy phase over that path fixes what the WFS DC signal should be. Nothing else is needed: the magnitude follows from the beam radius at the actuator, the phase from the accumulated Gouy phase.


Results

actuator sensor-basis direction [deg] magnitude [(Δx/w) / cnt]
predicted measured meas − pred predicted measured meas / pred
PZT PIT -111.00 -115.82 -4.82 1.487e-4 1.520e-4 1.022
PZT YAW -108.96 -107.68 +1.29 9.790e-5 8.968e-5 0.916
JM1 PIT -47.99 -52.90 -4.91 7.967e-5 7.598e-5 0.954
JM1 YAW -56.87 -32.19 +24.68 6.895e-5 7.471e-5 1.084

The direction is the angle of the (WFS A, WFS B) response vector, and the magnitude is its length in units of normalised beam displacement per drive count. Three of the four lines agree with the prediction to within 5 deg in direction, and the magnitudes agree to within 8% (max/min 1.183 across the four, std(log) 0.064). 

The two excitation methods agree with each other: comparing the sensor-basis direction obtained from the calibration lines against the one obtained from the broadband injection gives +6.79, +5.56, -0.24 and +0.19 deg for PZT PIT, PZT YAW, JM1 PIT and JM1 YAW. 

JM1 YAW is the exception, off by +24.68 deg. Why this one line alone fails to be predicted is not yet understood. Several explanations were tried and none survived: moving JM1 along the beam would need 29 cm; moving WFS B by 2.5 cm removes the JM1 YAW discrepancy but drives JM1 PIT from -4.9 to -30 deg; the astigmatism degeneracy in the layout fit spans 2.1 deg against the 14.3 deg required; the ghost beam is ruled out because the result is unchanged across the ghost dump (we did same measurement before the ghost beam dump campaing); and the yaw to length coupling of the suspension would need to be of order 10 um for against the 0.003 um the JM1 OSEMs seee. 

Images attached to this report
LHO General
ibrahim.abouelfettouh@LIGO.ORG - posted 18:13, Thursday 13 August 2026 (91531)
OPS Eve Shift Summary

TITLE: 08/14 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

IFO is in IDLE with the IMC Locked

Good progress today with locking DRMI, which is now consistently locking for a few minutes - alog 91530

LOG:

Start Time System Name Location Lazer_Haz Task Time End
15:26 fac kim FCES - technical cleaning 17:03
15:37 sqz sheila.camilla.ryanS CR y HAM7 closeout/backscatter meas 17:18
16:05 laser camilla East Bay Yes Transition to Local Laser Hazard in East Bay 16:12
17:03 fac chris lvea - famis checks 19:02
17:05 vac gerardo lvea - opening HAM1 ion pump 17:11
17:17 laser camilla LVEA - Taking East Bay to SAFE 17:45
17:20 beck daniel cr - beckhoff reboot 17:24
17:21 sus ryanC lvea - grabbing PSAMs parts in East Bay 17:28
17:26 deteng betsy lvea - lvea walkthroough 17:30
17:33 sei jim EastBay - Unlock/Balance/Closeout TFs 19:11
17:44 sqz sheila.ryanS EastBay - ham7 clean-up 17:45
17:58 ias jason lvea - looking for any alignment stuff in lvea 18:03
18:05 deteng mitch lvea - inventory checks 18:58
18:40 crs shoshonna lvea - crs laser on at rack 20:33
18:43 ee fil mezzanine - bypass ham7 high voltage 19:00
18:55 pem carlos lvea - measuring cables 19:11
19:07 ee betsy.fil lvea - ground loops @HAM7 19:51
19:21 crs shoshonna.huyen lvea - turning crs laser off 19:40
19:21 sqz camilla East Bay - moving table out of way @Ham7 19:37
19:33 ham7 jim HAM7 - pulling something out of bottom of HAM7 19:42
19:34 fac travis ham7 - HAM7 sealing up 23:41
19:49 sus ryanC lvea - grabbing pelican case 19:53
22:04 deteng ibrahim EastBay - grabbing tool pans around ham7 22:21
23:08 pem dave.miranda CER - fixing cables 23:12
23:30 crs shoshonna.jim.huyen cer.ham3Rack - CRS measurements 23:48
00:30 VAC Gerardo LVEA N Taking HAM7 Chamber Pics 00:40
H1 ISC (ISC)
masayuki.nakano@LIGO.ORG - posted 17:47, Thursday 13 August 2026 (91530)
DRMI lock trial

[Sheila, Ryan, Masayuki]

We got DRMI to lock for several minutes. By the end of the session it was re-locking every one to two minutes, though each stretch of lock lasted less than five minutes. 


After locking PRMI and aligning the BS and the PRM, we requested ACQUIRE_DRMI_1F and tried several combinations of the PRCL/SRCL/MICH gains. Eventually we found the combination which can grab the DRMI lock, and that was the original gains except for PRCL. The PRCL gain had been doubled yesterday (input matrix 1.75 -> 3); we reduced it to 2.5, and with that we could lock several times.

In the short stretches of lock we measured the OLG of each loop. PRCL and MICH both have a strange phase rotation around 10 Hz. The MICH loop gain was also on the low side, so I increased it and tried to lock again.

While waiting for the next lock in that configuration, I moved the SRM more or less at random by ~20 urad in pitch and yaw, and found that the better alignment made POP90 more stable (see attached plot). In that stretch I re-measured the MICH OLG, and its UGF was close to what we had for PRMI. So this looks more like an alignment issue than a loop gain or loop shape issue.

I then found that the MICH loop gain was by now too high to engage the boost (FM1 of MICH1), so I halved it. With that gain the guardian could engage all the filters in the DRMI_LOCKED state.

I measured the SRCL gain again and it came out lower than in our first measurement, though I am not sure that measurement is valid. I tried a higher SRCL gain and it seemed unstable, but that may have been the alignment degrading rather than the gain itself.

I stopped here. The guardian is left in the configuration that felt like it gave the most frequent locks.

The attached TFs are the first MICH/PRCL/SRCL gain measurements, and the SRCL gain measured just before I finished (second left hand side).

Images attached to this report
LHO General
corey.gray@LIGO.ORG - posted 16:35, Thursday 13 August 2026 (91509)
Thurs DAY Ops Summary

TITLE: 08/13 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY:

HAM7 close out work with both doors being installed and even the Annulus Ion Pumps pumping on the doors

Detector locking had DRMI locks---longest was around 5min!  So troubleshooting continues.
LOG:

H1 SEI
shoshana.apple@LIGO.ORG - posted 15:58, Thursday 13 August 2026 (91512)
Mode Hopping in CRS laser

 

Images attached to this report
H1 AOS
betsy.weaver@LIGO.ORG - posted 14:59, Thursday 13 August 2026 (91529)
HAM7 Ground loop checks

Fil, Betsy

Today Fil and I did a quick repeat of T2200048 HAM7 ground loops check just before doors are going on.

Last checks were done:

Feb this year by Camilla/Sheila https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=89048

Feb 2022 Fil/me https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=61738

Keita had done them prior, hence the document.

We basically found the same results as Camilla/Sheila namely:

All the rest were "open".

H1 ISC
ryan.short@LIGO.ORG - posted 14:19, Thursday 13 August 2026 (91528)
PRMI Alignment Signals Comparison

In our PRMI locking today, Sheila had me compare some signals from today to a past PRMI time and pointed me to alog91238. We weren't sure however if these numbers made sense, so I found another PRMI time from November (specifically Nov 26th, GPS 1448216615, PRMI ASC converged) and re-did the comparison to today.

  POP_A_LF POPAIR_B_LF REFLAIR_A_LF POPAIR_B_RF18_I POP_X_DC_NSUM POP_A_NSUM POP_B_NSUM
PRMI Nov 26th 84 17 2.55 85 0.082 (seems low, may not have been well aligned) 80 73
PRMI today 30 6 2.57 30 160 8 5

 

H1 SYS (CDS)
filiberto.clara@LIGO.ORG - posted 14:00, Thursday 13 August 2026 (91525)
Electronics for IFO Analog Cameras Decommissioned

WP 13511
FRS 33242

The electronics for the IFO analog cameras were uninstalled. No impact to the PSL and building cameras (access sytem). Analog cameras were left installed, available for local monitoring. The single fibers used to connect from each end station to the corner station are now available/spares. The MSR Video Rack 7 is mostly empty.

F. Clara, J. Figueroa

Images attached to this report
H1 SUS (SUS)
rahul.kumar@LIGO.ORG - posted 13:38, Thursday 13 August 2026 (91524)
Spare ZM5 (PSAMS - s/n 02) unit repaired with a new PZT - 65in-lb pre-load applied on the mirror.

Ryan C, Rahul

This unit will be shipped to CIT for ROC measurements on Zygo interferometer. This will then be return to LHO and stored in the desiccant cabinet as a spare ZM5 unit.

We removed the broken PZT and replaced it with a new one sent by Camille.

The strain gauge resistance  was measured to be around 700 ohms and 360ohm and the PZT capacitance was around 20 uF.

Details - s/n 02, mirror pre-load value = 65 in-lb.

H1 SUS
sheila.dwyer@LIGO.ORG - posted 12:37, Thursday 13 August 2026 - last comment - 09:08, Friday 14 August 2026(91522)
PR2 ringing at 1 Hz

Masayuki, Sheila

When we step the alignment sliders in pitch or yaw on PR2, we see 1 Hz ringing for 15-20 seconds.  

Images attached to this report
Comments related to this report
rahul.kumar@LIGO.ORG - 14:05, Thursday 13 August 2026 (91527)SUS

Keeping an eye on PR2, took an osem spectra of the inmons and don't see anything abnormal in the suspension right now - but will keep investigating it if these oscillations returns.

Images attached to this comment
masayuki.nakano@LIGO.ORG - 09:08, Friday 14 August 2026 (91538)

This is Sheila

It seems like this ringing at 3Hz has been seen in PR2 for about the last month.  A step of 2urad in pitch causes a ringing with an intial amplitude of 5 urad at 1 Hz that damps down over about 20 seconds.  For yaw the magnitudes are similar, the ringing amplitude is about twice the amplitude of the step.  

Images attached to this comment
H1 IOO
daniel.sigg@LIGO.ORG - posted 12:26, Thursday 13 August 2026 (91521)
Heater controller for JAC

I copied the OPO TEC controller code and modified it to use for the JAC heater.  

The controller uses the H1:JAC-HEATER_DRV_VSET_OFFSET channel to add its control output to the heater.  The controller gain needs to be negative.

Atteched a screeshot of the new screens.

Images attached to this report
H1 SEI
jim.warner@LIGO.ORG - posted 12:21, Thursday 13 August 2026 (91520)
HAM7 ISI tfs look as good as ever, ok to close

SQZ finished in HAM7 this morning, I've now unlocked, rebalanced the table and taken ISI close-out tfs. I believe it is a known issue with this chamber, but the resonances aren't as clean to resolve as they generally are for other tables, but todays measurements look very similar to my previous measurements. For the attached plots, refs 0-5 are the l2l gs13 tfs from February this year, 6-11 are from today. I think we are okey to close.

Images attached to this report
H1 IOO (IOO)
masayuki.nakano@LIGO.ORG - posted 22:31, Tuesday 11 August 2026 - last comment - 13:02, Thursday 13 August 2026(91487)
Absolute angular calibration of the JAC steering actuators from the second harmonic of the cavity transmission.

Summary

We have calibrated the two JAC steering actuators the PZT (IO_MB_M4) and the JM1, in μrad per drive count at DC. The scale comes from the second harmonic of the cavity transmission under a dithered drive, which is insensitive to DC misalignment and so needs no external angle reference. 


Method

By expanding the injected field in the cavity's own eigenmode basis, we can describe the misaligned as,

Ein(t) = E0 + δ(t) E1

with E0 the cavity's TEM00 mode and E1 the TEM10 (pitch) or TEM01 (yaw) mode, orthonormal. As long as the misalignment is small enough comparing to the beam size, the single complex coefficient δ carries the whole misalignment on that axis: its real part is a transverse displacement in units of the waist size, its imaginary part an angle in units of the divergence angle. Only the TEM00 is resonant, so the transmitted power follows the fraction of the input that sits in E0, i.e. 1 − |δ|2 for |δ|2 « 1.

Dithering a steering actuator makes δ oscillate about whatever value it already had:

δ(t) = δofs + δa cos(2πft)

where δofs is the static misalignment already present, and δa is the dither we deliberately applied, which is exactly the quantity we want in order to calibrate the actuator. TRANS signal (1 − |δ|2) can devided into three components with its frequecies:

frequency value contains the unknown δofs?
DC ofs|2 + |δa|2/2 yes
f 2 Re(δofs*δa) yes — magnitude and relative phase
2f a|2/2 no

The static offset drops out of the second harmonic algebraically. 2f therefore delivers a| with no reference to the alignment state we happened to be sitting at, and with no external angle standard. The DC and f terms, the two one would reach for first, are both contaminated by it.

This is the whole point of the method, and it is directly visible in the plot. adding a static offset grows the 1f line by +528 % while the 2f line moves by +8 %, its own measurement noise.


Measurement

I proceeded 4+1 measurement in total with the JAC locked. For each measurement, one actuator axis was dithered at 11 Hz, with the excitation injected on the channels below and the drive read back on the corresponding _OUT. I excited JM1/PZT PIT/YAW per one measurement, and the other one is the PZT_PIT excitation with static offset (30 cnts) to demonstrate that the 2f peak is not affected by the offset. Transmission was read on H1:JAC-TRANS_A_LF_OUT.

record excitation channel drive read back on amplitude at 11 Hz [cnt] drive offset [cnt] TRANS DC [cnt]
PZT_PIT H1:JAC-PZT_PIT_EXC H1:JAC-PZT_PIT_OUT 20.0 0 6451.2
PZT_PIT_ofs H1:JAC-PZT_PIT_EXC H1:JAC-PZT_PIT_OUT 20.0 30 6442.5
PZT_YAW H1:JAC-PZT_YAW_EXC H1:JAC-PZT_YAW_OUT 20.0 0 6442.6
JM1_PIT H1:SUS-JM1_M1_TEST_P_EXC H1:SUS-JM1_M1_TEST_P_OUT 40.0 0 6445.5
JM1_YAW H1:SUS-JM1_M1_TEST_Y_EXC H1:SUS-JM1_M1_TEST_Y_OUT 40.0 0 6440.2

a| is calculated from peak heights of the transmission at 22 Hz, converted to a mirror tilt using the local beam radius at each actuator from the current JAC reflected-path layout model (alog91472 comment), and calibrated into DC responce using each actuator's frequency response as measured (described below).


Results

actuator axis excitation channel a|2 efficiency [μrad/cnt]
at 11 Hz (as measured) at DC
PZT PIT JAC-PZT_PIT_EXC 1.09e-5 0.0093 0.083
PZT YAW JAC-PZT_YAW_EXC 6.47e-6 0.0093 0.079
JM1 PIT SUS-JM1_M1_TEST_P_EXC 1.01e-5 0.0216 0.89
JM1 YAW SUS-JM1_M1_TEST_Y_EXC 1.67e-5 0.0254 0.92

The 11 Hz column is what the dither actually produced; the DC column is that value divided by the actuator's own response at 11 Hz, and is the number to use for a DC gain. 


Appendix

Actuator frequency response

The frequency response itself comes from a separate set of four broadband actuator-to-wavefront-sensor records (300 s each, one actuator per record, see atatched plots), from which the JM1 suspension resonance and the PZT drive pole are fitted. Only the shape of those transfer functions is used; their absolute scale plays no role in the calibration.

The fitted frequency responses are:

AOI compensation

Both actuators sit at a design AOI of 45°, and the rows above include the geometric correction that follows. A tilt whose rotation axis lies in the mirror surface and in the plane of incidence steers the beam by only 2θ cos(AOI), against the full for the axis perpendicular to that plane. At the PZT the suppressed axis is YAW in the cavity-referred channel naming (the HAM1 periscope exchanges the transverse planes downstream of it); JM1 sits after that periscope, so for it the suppressed axis is PIT. The assignments follow from each mirror's orientation, and the correction uses the design 45° rather than a value fitted to the measured ratio.

Cross-checks

Images attached to this report
Comments related to this report
masayuki.nakano@LIGO.ORG - 13:02, Thursday 13 August 2026 (91523)

Short note: a mirror rotated by θ, sitting where the beam radius is w(z), produces |δ| = k w(z) θ, and its phase relative to TEM00 is 90° plus the Gouy phase accumulated from the reference waist. This can be applied for the mirror which is transmitting the lens. This is because δ is the field amplitude of the first-order mode it is continuous across lenses, so a mirror separated from the reference space by lenses is handled by simply adding up the free-propagation Gouy phase to the reference waist. The table below therefore carries the beam radius and the accumulated Gouy phase at each actuator.

actuator axis excitation channel a|2 efficiency [μrad/cnt] beam radius
w [mm]
Gouy phase from
the JAC waist [deg]
at 11 Hz (as measured) at DC
PZT PIT JAC-PZT_PIT_EXC 1.09e-5 0.0093 0.083 3.020 -86.4
PZT YAW JAC-PZT_YAW_EXC 6.47e-6 0.0093 0.079 3.270 -73.5
JM1 PIT SUS-JM1_M1_TEST_P_EXC 1.01e-5 0.0216 0.89 0.620 -32.7
JM1 YAW SUS-JM1_M1_TEST_Y_EXC 1.67e-5 0.0254 0.92 0.681 -30.8

The beam radius (1/e2 intensity) and the Gouy phase are model values at the actuator, taken from the JAC REFL optical model.

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