TITLE: 11/21 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Preventive Maintenance
INCOMING OPERATOR: Corey
SHIFT SUMMARY: Busy maintenance day; SQZ cabling (PMC, OMC), PSL Refcav alignment, ISS 2nd loop, VAC turbopump checks, valves and gauges added to FCT, ALS laser adjustments at EX, HWS work also at EX, cleanroom building at EY, and camera fibers reseeded in the MSR. Back to NLN at 06:00UTC! Lockloss 12 seconds later :(

HAM7 ISI tripped at 17:59 and 18:03 presumably from the SQZ rack work, HAM2 ISI tripped at 18:19 from the measurements being run on HAM2/3. Picket-fence plot died around 18:05 but was able to restart itself after 2 tries and ~5 minutes. Microseism is the highest its been in ~265 days, above the 90th percentile for the past ~12 hours.

Something happened at EndX at 19:29:21, the ISIs state1&2 tripped and so did the HEPI, not sure why, there was no one down there at the time and a DAQ restart was underway. All the sei signals went to zero, the SUS seems fine. After lots of checks and other restarts Erik went down to EX to physically powercycle some chassis, AA, IOP, Fil later joined him, the -18V DC Kepco power supply was found to have failed. FRS ticket 29752, alog74341

21:18 Started to relock

• Green arms went through some rounds of increase flashes (1 for X, 2 for Y), Y arm eventually said "Find by hand" and then I brought it to unlocked and found it by hand (I had to touch ETMY, TMSY, & ITMY) and got flashes to about 95% and then it was able to lock
• Small flashes on DRMI, nothing on PRMI, CHECK_MICH couldn't get MICH_BRIGHT and neither could I by hand so I went to an Initial alignment at 22:26UTC where I had to intervene during SRC/SRY locking and touched SRM. Finished at 22:54
• PRMI was able to easily lock afterwords but DRMI still struggled despite decent flashes, after 4 PRMI locks we were able to lock DRMI
• Violins were a little high

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FAMIS tasks 24845 and 24869

Procedure checklist for both stations completed.  No issues were identified at this time.

MX: Scroll pump hours: 208.9

       Turbo pump hours: 118

       Crash bearings: 100%

EX: Scroll pump hours: 6374.8

       Turbo pump hours: 274

       Crash bearings: 100%

Today Daniel, Sheila, Dana, and myself went to EX to look further into the ALS system to hopefully fix the locking trouble that we've had (summary in alog74323). We hooked up a spectrum analyzer before the phase frequency discriminator and verified that we saw the 40MHz signal that should be there. We then checked on table to make sure that there was no clipping on the beatnote path (table layout - D1800270). The two beams looked decently co-aligned after ALS-BS3, and while it wasn't perfect it was deemed good enough. The beam on the ALS-M3 mirror was on the very far edge of the optic, but seemed to be fully making it to the BBPD ALS-PD7.

While we were looking at the beam on the table, Daniel tried tuning the temperature and current of the laser and ended up back at the settings we started with (June 30th alog70976).

There was no obvious reason for any of the locking troubles we've seen recently, and now the beatnote power (H1:ALS-X_FIBR_A_DEMOD_RFMON) seems to be back up to where it has been even though we didn't make any changes. I guess we'll revisit this in 6 months when it happens again...

R. Short, J. Oberling

As we've been seeing the FSS RefCav TPD dropping over the past couple of weeks, this morning Jason and I did a proper tune-up of the RefCav alignment. We started by remotely aligning the beam into the RefCav from the control room using the two picomotor-controlled mirrors in the FSS path. With the ISS on and the IMC unlocked, the signal on the TPD started and ended at:

• Start: 0.69 V
• Finish: 0.76 V

Only seeing a slight improvement in the RefCav TPD signal with the picomotors, we then proceeded to head into the PSL enclosure to touch up the FSS path alignment. We started with a power budget on the FSS path (done with the ISS on and both PSL Guardians paused):

• FSS In: 300.0 mW
• AOM In: 295.5 mW
• AOM Out (Single Pass): 210.1 mW
  • Diffraction Efficiency: 71.1%
• AOM Out (Double Pass): 131.9 mW
  • Diffraction Efficiency: 62.8%
• EOM Out: 136.8 mW

The most obvious issue appeared to be the double pass through the AOM, as Jason had left the diffraction efficiency at around 73.8% after the last on-table FSS alignment, but we decided to start from the highest point upstream and make adjustments at each point. We adjusted WP05 to improve AOM IN, the AOM (mostly upwards in height) to improve single pass diffraction, and mirror M21 to improve double pass diffraction. Our results:

• AOM In: 300.0 W
• AOM Out (Single Pass): 223.7 mW
  • Diffraction Efficiency: 74.6%
• AOM Out (Double Pass): 158.1 mW
  • Diffraction Efficiency: 70.7%

Good improvements all around, and although neither diffraction efficiency ended as high as after the last alignment, with an unlimited maintenance window I suspect we would see more gains. We then checked the alignment through the EOM; seeing it was good with no clipping and measuring 158.4 mW out, we moved on to recovering the RefCav using the iris mounted in front of it. With the RefCav now locked, we touched up the alignment using the picomotor-controlled mirrors while watching the signal on the TPD:

• Start: 0.85 V
• Finish: 0.99 V

Excellent. Using a multimeter to watch the DC voltage, we then touched up the alignment onto the RefCav RFPD by adjusting mirror M25:

• Start: 1.210 V
• Finish: 1.316 V

To finish off our activities in the enclosure, we measured the RefCav's visibility:

• Unlocked: 1.316 V
• Locked: 0.220 V
• Visibility: 83.3%

After returning to the control room, we resumed the PSL Guardians, turned the ISS back on, and adjusted the ISS RefSignal to -1.97 V to keep the diffracted power around 2.5%. I have not accepted this value in SDF as it will likely need to be adjusted periodically this evening/tomorrow as the enclosure comes to thermal equilibrium. This closes WP 11537.

WP 11533

Checked the HAM4 ISI Coil Driver Chassis. Issue reported last week of noisy fan. Fan is spinning and noise reported last week has not returned. Will leave WP open another week.

WP 11532

Functionality of the ETMX SUS Hardware Watchdog was tested this morning. System had reported no triggers over the past few months. One of the DB37 field cables was disconnected. Both the software and front panel LEDs went into alarm. Field cable was reconnected and system returned to nominal state.

D. Barker, F. Clara

TJ, Camilla

After swapping to the old ETMX HWS 530nm diode source and seeing that the HWS signal was not good in 73717, TJ and I this morning confirmed that the mode matching does not match the design. We think we need to adjust the position if the initial collimating lenses, but didn't finish doing this. As we misaligned the beam by movng the fiber assembly D1800125, we left the HWS powered off. Accepted in sdf. 

Gabriele refit the 11/15 LSC FF data 74220, allowing a higher magnitude at low frequency to give us a better fit, fit attached. I lowered the Q of the 17.7Hz feature and added this filter to MICHFF FM8 as "11-15-23B".  We'll want to turn this FF slowly or before Tuesday Maintenance, as the excess low frequency could cause instability.

Plot attached, red is current MICHFF FM7,  blue is new FM8 (double the strength of current FF <8Hz), green is Gabirele's original design before adjusting Q of 17.7Hz feature (all including the high pass filter in FM10).

I lowered the 17.7Hz Q's by a factor of 4 from the original design, to minimize effect on KAPPA_TST error 74259:

• Pole @ 17.8247Hz, Q =  194.416 -> reduced to Q = 48.604
• Zero @ 17.7598Hz, Q = 170.142 -> reduced to Q = 42.535

R. Short, with guidance from K. Kawabe and J. Oberling

I've made some updates to the 'CLOSE_ISS' state in the IMC_LOCK Guardian, which handles the closing of the ISS second loop, that should make the closing of the second loop more consistent.

When the second loop is engaged, the DC working point of the ISS is determined by the output of the second loop's digital AC coupling (H1:PSL-ISS_SECONDLOOP_AC_COUPLING_DRIVE). This output is held when the second loop is closed, but it can occasionally be held far from the average of its oscillations before the second loop is engaged, which in the past has caused locklosses and was mitigated earlier this year (see alog 67347). While the second loop isn't causing locklosses anymore (that I can recall), we do still see the digital AC coupling output being held slightly off from the mean, causing the diffracted power to jump. I've expanded upon Georgia's logic by changing the way the output of the AC coupling drive is held to be more consistent. Instead of waiting to hold the output until it's near the mean over the past 10 seconds (a calculation that itself can take several seconds), the process is now as follows:

1. Take a 10-second average on the AC coupling drive output
2. Hold the output
3. Write the 10-second average value to the AC coupling drive's offset
4. Turn off the input and turn on the offset
5. Unhold then rehold the output (to grab the offset value)
6. Perform Georgia's "within 100 counts" check on the output
7. If successful, zero the offset and turn back on the input

I was able to test this logic during the maintenance period today, both with the IMC locked at 2W and 60W, with great success. We'll run with this for a while to see if over several lock acquisitions the second loop is being engaged with a more consistent digital AC coupling drive. The updated IMC_LOCK Guardian code is loaded and committed to SVN.

LVEA Swept following T1500386. WAP and lights off. Noticed nothing other than what Oli wrote in 73244. Loudest things are VAC computer stands and CER fans. 

I added roughly 5 meters of LMR 195 to the cable sending the 3MHz local oscillator to the demod for the OMC 3MHz signal.  This should add roughly 21ns of delay, or roughly 23 degrees of phase for the 3MHz signal. 

We are hoping that this will shift the turn around point of the ADF sqz angle readback so that our operating point is at a better place to use this readback to adjust the sqz angle. (for background see 74256

This means we will need to retune the SQZ angle before we to observing today.

Maintenance tasks have wrapped up but team CDS and SEI are trying to solve a problem that showed up at 19:29UTC on EndX where we lost all SEI signals (went to exactly zero). Microseis remains elevated, above the 90th percentile for the past ~16 hours and based on its trend visually it will probably take another 6 hours to get fully below that mark.

Once this issue is resolved we will resume attempting to lock.

Fil Daniel

PMC install preparation:

• Extended the rack rails on top of SQZT0 to enable mounting the laser locking fiber beat note chassis.
• Installed the auxiliary signals concentrator 11 into the remote squeezer rack.
• Installed the long coax cables going from the remote squeezer racks to SQZT0.

Tue Nov 21 10:14:21 2023 INFO: Fill completed in 14min 16secs

I grabbed an ETMY OPLEV charge measurement this morning before the cleanroom work started.

Naoki, Sheila

In the AS72 sensing matrix measurement in alog74106, Daniel suggested to increase the whitening gain of AS72 since it could be limited by ADC noise. We checked the whitening filter of AS72 A and B. Both of them have 12dB whitening gain, but one stage whitening is engaged for AS72 A, while two stage whitening is engaged for AS72 B. We decided to engage the 2 stage whitening for AS72 A, which is used in SRC1. The IFO locks without any problem with this additional whitening. We accepted some SDFs as shown in the attached figures. We will try to increase the whitening gain later.

I went back and forth (~5 mins each) with the BS M2 coil drivers between their nominal low noise state, and their higher noise higher range state. 

When in the higher noise state (state 2), there seems to be consistently higher noise between about 55 Hz up to 100 Hz. In the attached plot the blue / green is the nominal low noise state, while red / pink is the high noise state.

I'll work on making this an actual noise projection that we can include in the noise budget, using Craig's code for quad PUM noise as a guide.

We were in the high noise state 2 from 20:56:45 - 21:04:00.  Then in low noise state from 21:06:10 - 21:11:15 (there's a glitch during this time).  Back to high noise from 21:13:20 - 21:19:40 (there's a small glitch during this time).  Back to low noise from 21:21:50 - 21:28:00.  All times UTC on 8 Nov 2023.  After this I handed back to Robert.