As the FSS RefCav TPD has been trending down and a remote alignment did not improve it, I went into the PSL enclosure this morning to tweak the beam alignment on the table.  All work was done with the ISS ON unless otherwise noted; I had to increase the ISS RefSignal from -2.00V to -1.98V to keep the ISS stable with the enclosure environmental controls ON.  In addition, the IMC was OFFLINE for the duration of my time in the enclosure.

I started by taking a power budget of the FSS path:

• FSS In: 290.9 mW
• AOM In: 289.9 mW
• AOM Out, Single-pass: 175.0 mW
  • Single-pass diffraction efficiency: 60.4%
• AOM Out, Double-pass: 125.7 mW
  • Double-pass diffraction efficiency: 71.8%
• EOM Out: 125.7 mW

Seeing the single-pass diffraction efficiency low, I adjusted the AOM alignment to improve it; the AOM had to be moved DOWN.  This resulted in the single-pass AOM output at 216.9 mW and a single-pass diffraction efficiency of 74.8%.  The double-pass AOM output was then measured at 155.4 mW, so I adjusted mirror M21 to see if I could improve it.  This resulted in the double-pass AOM output at 160.1 mW and a double-pass diffraction efficiency of 73.8%.  Much better.

I then double checked the beam centering on the EOM, which was good so I relocked the RefCav.  I needed to adjust mirror M23 slightly in pitch to get the RefCav REFL beam in roughly the same place on the REFL camera, then the RefCav autolocker locked it with no issues.  I used the picomotor mounts to tweak the RefCav alignment to max the TPD; this gave a TPD of 0.99 V.  Very good.  To finish I unlocked the RefCav, tweaked the beam alignment on the RFPD, then locked the RefCav again and measured the visibility:

• Unlocked: 1.326 V
• Locked: 0.225 V
• Visibility: 83.0%

Job done, I left the enclosure.  During my time in there the PMC Refl power had increased from ~16.1 W to ~17.9 W (this increase is normal with enclosure incursions), so I turned the ISS OFF while the PSL enclosure and PMC returned to thermal equilibrium.  At the time of this writing the PMC Refl power has dropped back to ~16.8 W, so I will continue to monitor it over the remaining maintenance time and turn the ISS back on once it gets closer to its normal value.  Also at the time of writing the IMC has been relocked; with the IMC locked the FSS TPD is ~0.96 V (the change with the IMC locked is normal).  This completes WP 11474.

Following alog 73227, reduced  H1:SQZ-SHG_FIBR_REJECTED_DC_POWER from saturated value of 0.7mW to 0.04mW.

TITLE: 10/17 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Preventive Maintenance
OUTGOING OPERATOR: Tony
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 4mph Gusts, 3mph 5min avg
    Primary useism: 0.06 μm/s
    Secondary useism: 0.41 μm/s
QUICK SUMMARY: Lost lock as I was typing out this log ending a 24.5 hour lock. Unsure of the cause. Primary and secondary useism are high, hopefully this is a non-issue for relocking after maintenance.

TITLE: 10/16 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 162Mpc
INCOMING OPERATOR: Tony
SHIFT SUMMARY:

- EX saturation @ 5:17

- 5:29 - inc 5.5 EQ from Iran

• 6:17 - EQ mode activated, back to CALM @ 6:27

- Violins have been stable over the course of the night after the ring heater changes from earlier today

- "PSL FSS TPD transmission low" notification has been popping up sporadically throughout the night - Tagging PSL
LOG:

No log for this shift.

H1 is still in observing, currently locked for 12.5 hours. Detector appears to be stable, ground motion is low, and the wind seems to be slowly going down (currently hovering ~15-20 mph).

TITLE: 10/16 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 152Mpc
OUTGOING OPERATOR: Ryan C
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 27mph Gusts, 23mph 5min avg
    Primary useism: 0.08 μm/s
    Secondary useism: 0.38 μm/s
QUICK SUMMARY:

- H1 has been locked for 8.5 hours

- CDS/DMs/SEI ok

- Wind is picking up, right around 35 mph gusts - will monitor throughout the night

TITLE: 10/16 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 149Mpc
INCOMING OPERATOR: Austin
SHIFT SUMMARY:

We dropped out of Observing to reverse the previously (last week, alog73445) done ring heater changes in 2 steps 2 hours apart, first step was done from 20:39:51 - 20:40:23UTC, the second was from 22:41:46 - 22:24:19UTC. alog73503

The wind has started to pick up over the past 2 hours, gusts up to 35mph which is probably what's degrading our range over the same timeframe, and microseism remains slightly elevated.

LOG:                                                                                                  

Ryan informed me at 20:48 UTC (13:48 PDT) that he was getting a PSL Chiller alarm, a likely indication that the level was low.  I had to watch the chiller for several minutes as the level slowly moved up and down with the regular flow of water in and out of the reservoir, but sure enough the water dipped just below the threshold and the chiller threw a Low Water Level alarm.  I added 150mL to get the reservoir to the Max line and the alarm went away.

We are averaging ~180mL of water added every 6 weeks, this has been fairly constant since late-April 2023.  I'll be in the enclosure tomorrow so will be able to do our customary leak check (a habit that's developed since we don't go into the enclosure unless necessary); I don't expect any leaks since the amount of water being added has not accelerated, but it's good practice to check while I'm in there.

To see if the range changes seen when we turned up the ETM RH from 1.0W/segment to 1.2W/segment in 73445 were real, this afternoon we are reversing this change.

At 20:40UTC, Ryan took us out of Observing to reduce both H1:TCS-ETM{X,Y}_RH_SET{UPPER,LOWER}POWER to 1.1W, we'll plan to reduce all the way to 1.0W in 2 hours.

The corner station dust monitor pump has failed. I am waiting for a quote for rebuild kits. The service kits we have on site are for the end stations only.

Closes FAMIS 26213
Laser Status:
    NPRO output power is 1.819W (nominal ~2W)
    AMP1 output power is 67.79W (nominal ~70W)
    AMP2 output power is 135.4W (nominal 135-140W)
    NPRO watchdog is GREEN
    AMP1 watchdog is GREEN
    AMP2 watchdog is GREEN

PMC:
    It has been locked 24 days, 4 hr 23 minutes
    Reflected power = 16.32W
    Transmitted power = 109.2W
    PowerSum = 125.5W

FSS:
    It has been locked for 0 days 6 hr and 52 min
    TPD[V] = 0.7082V

ISS:
    The diffracted power is around 2.3%
    Last saturation event was 0 days 6 hours and 55 minutes ago

Possible Issues: None

Mon Oct 16 10:09:16 2023 INFO: Fill completed in 9min 12secs

I received a text Sunday morning about moderately rising temps at EY. When logging into the FMCS, Chiller 1 was in a latched alarm. I enabled chiller 2 to run, as well as the chilled water pump 2. The two pumps ran in parallel for approximately 15 minutes before I commanded chilled water pump 1 off.

The latched alarm is once again an "Evaporator Flow Lost" likely from last week's work to fix the damaged wires/flow switch. No temperature excursions should be expected at that building. Work to remedy the latest issue will begin Thursday 10/19 

T. Guidry

TITLE: 10/16 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 156Mpc
OUTGOING OPERATOR: TJ
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 10mph Gusts, 8mph 5min avg
    Primary useism: 0.04 μm/s
    Secondary useism: 0.39 μm/s
QUICK SUMMARY:

• We've relocked following a 6.4 EQ from Alaska, locked for 36 minutes, in observing since 14:43UTC
• All systems look good, range is slowly increasing

ALS_DIFF had stepped over a resonant offset by about 35. I'm not yet sure if this offset is changing by this much each lock, or if there is something else going on.

[Vicky, Regina, Dorotea, Sheila]

The attached plot shows the ratio of green light transmitted vs reflected through the OPO over the past year to see how green OPO cavity losses have changed.

We last moved the OPO crystal in Nov. 2022 (see relevant alog). Shortly after moving the crystal, the ratio was around 5% and degraded to around 4% within the first week; it has since settled between 2-3% for most of the past year.

We think the discontinuity around 23/04/16 was due to rejecting power away from the refl PD, which was done around that time because the PD was being saturated. If we look at the refl power alone we can see clear saturation occurring on the PD in the time before the power was lowered. We think the loss curve would be fairly continuous if not for the saturation, but can't exactly compensate since we don't know how much power is being lost. The plot shows only times from when the detector was "stable", but stability was calculated fairly naively, leading to some outlier points remaining from when the detector wasn't actually locked; however, the general trend seems pretty consistent.

Both ETM RH turned up from 1.0W to 1.1W/segment at 19:03UTC, plan to increase another 0.1W later this afternoon. Follow on from 73437. Will stay in observing during this test.

To see if the OM2/beckhoff coupling is a direct electronics coupling or not, we've done A-B-A test while the fast shutter was closed (no meaningful light on the DCPD).

State A (should be quiet): 2023 Oct/10 15:18:30 UTC - 16:48:00 UTC. The same as the last observing mode. No electrical connection from any pin of the Beckhoff cable to the OM2 heater driver chassis. Heater drive voltage is supplied by the portable voltage reference.

State B (might be noisy): 16:50:00 UTC - 18:21:00 UTC. The cable is directly connected to the OM2 heater driver chassis.

State A (should be quiet): 18:23:00- 19:19:30 UTC or so.

DetChar, please directly look at H1:OMC-DCPD_SUM_OUT_DQ to find combs.

It seems that even if the shutter is closed, once in a while very small amount of light reaches DCPDs (green and red arrows in the first attachment). One of them (red arrow) lasted long and we don't know what was going on there. One of the short glitches was caused by BS momentarilly kicked (cyan arrow) and scattered light in HAM6 somehow reached DCPDs, but I couldn't find other glitches that exactly coincided with optics motion or IMC locked/unlocked.

To give you a sense of how bad (or not) these glitches are, 2nd attachment shows the DCPD spectrum of a quiet time in the first State A period (green), strange glitchy period indicated by the red arrow in the first attachment (blue), a quiet time in State B (red) and during the observing time (black, not corrected for the loop).

FYI, right now we're back to State A (should be quiet). Next Tuesday I'll inject something to thermistors in chamber. BTW 785 was moved in front of the HAM6 rack though it's powered off and not connected to anything.