Madi, Camilla

Started ETMX Ring Heater test for HWS testing, turned up from 1W/segment to 2W/segment. Plan to leave until tomorrow.

TITLE: 04/20 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: Some BSC2 and cabling work done today. HAM5 and HAM6 HEPI are going to be down overnight since the HEPI pump is having issues.
LOG:

In prep for WP13185 to replace the flex lines on the table and the expansion joint, I've drained and vacuumed the TCSX table and then I just used gravity to drain most of the water in the supply line, enough so that the expansion joint is free of water.

WP13182 BRS-EX recovery

Jim, Patrick, Dave

I tried to reboot, but ended up power cycling, h1brsex. Patrick started the code and IOC. Since then it has been attempting to damp over the past few hours.

FAMIS 31134

The ISS diffracted power has drifted down a bit over the past few days, so I'll bring that back up towards 4%. No other major events of note.

Mon Apr 20 10:09:19 2026 INFO: Fill completed in 9min 16secs

TITLE: 04/20 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: 9mph Gusts, 5mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.19 μm/s 
QUICK SUMMARY:

BSC2 work today

ETMY SWWD tripped at 01:17 PDT this morning due to an EQ. I have reset the DAC drives.

Sun Apr 19 10:06:23 2026 INFO: Fill completed in 6min 19secs

Sat Apr 18 10:08:36 2026 INFO: Fill completed in 8min 33secs

BSC6 annulus ion pump railed about 20 minutes ago, there appears to be a little communication to the main vacuum volume noted on PT410B, however it may just be electrical noise due to the change reported by PT410B, very small, its changes it is not replicated by other gauges, like PT424B.  Nothing to do about it right now, but we will check the annulus system ASAP.

TITLE: 04/17 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: No further work was done regarding BSC2
LOG:

Fri Apr 17 10:10:13 2026 INFO: Fill completed in 10min 9secs

Closes FAMIS#39760, last checked 89840
Laser Status:
    NPRO output power is 1.83W
    AMP1 output power is 70.39W
    AMP2 output power is 137.9W
    NPRO watchdog is GREEN
    AMP1 watchdog is GREEN
    AMP2 watchdog is GREEN
    PDWD watchdog is GREEN

PMC:
    It has been locked 6 days, 23 hr 13 minutes
    Reflected power = 27.09W
    Transmitted power = 104.3W
    PowerSum = 131.4W

FSS:
    It has been locked for 6 days 23 hr and 13 min
    TPD[V] = 0.4872V

ISS:
    The diffracted power is around 3.6%
    Last saturation event was 1 days 19 hours and 33 minutes ago
Possible Issues:
    PMC reflected power is high

h1susey reported a DAC error with both its LIGO-DACs at 17:32 Thursday 16apr2026 PDT. This was caused by a large timing glitch seen on h1iopsusey and h1susetmy at this time, cpu_max of >200uS were seen on both models. This was a recoverable error and DAC0 continues to drive.

The lights were not on at EY at this time, so it does not appear to be related to any in-rack work.

dmesg:

[Thu Apr 16 17:32:21 2026] h1iopsusey: ERROR - LIGO_28AO32(0) DAC error detected, 0x30070086, DAC error counter: 19, is_locked: 1
[Thu Apr 16 17:32:21 2026] h1iopsusey: ERROR - LIGO_28AO32(1) DAC error detected, 0x30070086, DAC error counter: 19, is_locked: 1
 

Jennie W, Sheila D, Jenne D

Summary: JAC TRANS A LF calibration gives correct ratio now but PD is too noisy to give us sensible values when the light pipe is closed.

On Tuesday I changed the scaling filter in JAC-TRANS_A_LF to give us an output calibrated in W out of HAM1. The previous calculation (alog #89805) gave us too large a value.

When we checked the power on the JAC-TRANS PD in chamber (alog #89251) we did not monitor the JAC input power between successive measurements and since we had purge air on I think the input power drifted.

To avoid confusion  I just took a time when the output power was measured in chamber and used the JAC TRANS LF OUTPUT power at that time to give the calibration into HAM2 W.

When we measured 96mW out of HAM1, the JAC-TRANS_A_LF filter bank was roughly calibrated into mW (using standard values for V/count, A/V, mW/A) but had not been calibrated using in-chamber measurements.

For 96mW we got 0.00120mW on JAC_TRANS_A_LF_OUTPUT on 2026/02/24 at 20:30:10 UTC, see image.

We want the output in W so the calibration factor is 80000/1000. This value is now in FM10 in the filter bank. Unfortunately the signal still is too nosiy to give a sensible looking value and so changes from -20 to 20 W.

Jenne and I put a 0.01Hz pole to low pass the noise in the FM7 filter, and also tuned the offset on the filter bank.

This channel still seems too noisy though (image) and changes between -0.5 W and 0.5.

So maybe we need a filter that goes down to lower frequency, or its just too noisy a PD to use as a JAC input power monitor.

I'm going to revisit this after the BSC2 work when we next have an opportunity to open the light pipe.

Closes FAMIS 28639

Last checked in alog 89720

TCSX read 30.8 - nothing added

TCSY read 10.6 - nothing added\

No water in small cup under the slow leak

TCSX is reading HIGH PRESSURE FAULT. See attached picture. 

FRS37572 ISI HAM and BSC WD Plots Not Working

Ryan C, Erik, Dave:

The MEDM buttons to plot the latest ISI WD trips (see attached) have not been working for some time.

We found the issue was due to the wd_plot python code running in the conda environment had pydv issues, but if ran in native debian it worked.

Fixing the conda pydv issue would take significant resouces, so we chose to change the MEDM launcher to explicitly run local /usr/bin/python3.

The common MEDM file ISI_CUST_CHAMBER_WATCHDOG.adl in the isi/comon/medm/[hamisi, bscisi]/ directories were changed accordingly.

I tested with HAM2 and BSC3.

Naoki, Camilla, Sheila

We had another look at some signals that we could use to track or servo the SQZ angle.  

We turned the ADF back on, making a line at 1.3kHz in DARM, and tuned the demod phase for the ADF so that the SQZ angle readout was 0 for the angle we've been using for observing in this lock.  Camilla added a bandstop at 1.3kHz in the SQZ BLRMS4, sum and null channels and checked that the ADF isn't dominating those.  We did a sweep of the CLF6 demod phase like this, with the dither amplitude reduced comapred to Wed (0.01 instead of 0.03 CLK gain).  

In the first attachment we are using BLRMS 4 to demodulate for the noise lock signal, the second cursor shows that the zero crossing of the ADF SQZ angle and the noise lock both correspond roughly with the minimum of noise in the BLRM4 (1kHz BLRMs).  This isn't the same phase as the one that minimizes the brown trace, a blrms centered at 350 Hz. This means we have a frequency dependence of the SQZ angle, so we should probably look into things like the SRCL offset that might be causing this. 

Naoki then turned the ADF phase with the SQZ angle set to minize BLRMS3, as shown in the second screenshot from Camilla (at the begining here you can see that Naoki set the ADF phase so SQZ ANG was zero for CLF demod phase of 145).  We repeated the sweep and see that we have lower SNR for the noise lock using this lower frequency BLRMS, and that the ADF as it is now wouldn't make a good error signal for this sqz angle because it doesn't really go negative. 

Detchar:  We are planning to leave the ADF on over the weekend, which will create a line at 1.3kHz.  We are hoping to use this to track changes in the squeezing angle over time.  

Varun, Stefan

We measured the (one-way) SRC Gouy phase to be 28.97deg +-0.11deg (statistical) +-0.43deg (systematic).
We used a method pioneered in KAGRA (klog 9241 and 9246). A similar method was used for the PRC Gouy phase measurement(alog 52504).

Plots:
 - Plot 1: SRC scan across 6 fringes. Blue: AS_C_SUM, Red: AS_C_SEG2 (both derived from IOP channels). Magenta: round trip Gouy phase fit from the two results.
 - Plot 2: Raw data strech of 6 best fringes.

Method:
- Align BS and SRM (in SRY) carefully (especially BS)
- Misalign SRM by 70 urad (we did pos pitch)
- Let SRMI freely swing (i.e. SRM and BS aligned, PRC misaligned)
- SRCL1 and MICH1 gains 0 (we don't need the control loops)
- Put an offset in SRCL2_OFFSET (we used -1e6cts)
- Turn off all whitening on ASC-AS_C
- We want the LSC trigger to fire and stay latched (and apply the offset) when ASC-AS_C reaches the darkest possible spot.
  This corresponds to the BS in the correct position, increasing the finesse of the SRC to its maximum.
- We achieved that with a negative trigger matrix element, a slightly positive enable threshold (since AS_C swing slightly negative), and a very negative disable threshold
  We used: H1:LSC-TRIG_MTRX_4_14 =-100, H1:LSC-SRCL_TRIG_THRESH_ON = 0.015, H1:LSC-SRCL_TRIG_THRESH_OFF = -100
- To read the data we need the highest possible data rate. So in addition to H1:ASC-AS_C_NSUM_OUT we recorded the IOP channels
  H1:IOP-ASC0_MADC6_TP_CH9, H1:IOP-ASC0_MADC6_TP_CH10, H1:IOP-ASC0_MADC6_TP_CH11, H1:IOP-ASC0_MADC6_TP_CH12
- Those IOP channels are before the fixed anti-whitening filter. So we did the anti-whitening filter in diaggui ('zpk([40],[0.4],1,"n")').
- The 4 quadrants of ASC-AS_C saw different combinations of the higher order modes.
- We used SEG4 (CH9) for finding the 00 modes.
- We used SEG2 (CH11) and the sum of all 4 segments for 10 modes (red and blue traces respecively).
- We chose a bank of 6 fringes with very low AS_DC values - those have the highest finesse.
- A spline fit was used to interpolate the time to degrees in-between 00 peaks.
- We calculated the mean from the red and blue traces separately. Their mean is reported as final value.
- We calculated the standard deviation of the mean from the red and blue traces separately. The maximum of the two errors is reported as statistical  error.
- The difference between the red and blue result is reported as systematic error.

The code and raw data is found in /ligo/home/controls/sballmer/20191022.