Sheila, Camilla, Robert

A change in the ETMX measured charge over the O4a-O4b break (e.g. 78114 ) suggested that there might be a change in electronics ground fluctuation coupling. This is because the hypothesized mechanism for ground fluctuation coupling depends on the test mass being charged so that, as the potential of electronics (such as the ring heater and the ESD itself) near the test mass fluctuate with electronics ground potential, there is a fluctuating force on the test mass.

We swept the bias (see figure) and found that the minimum in coupling had changed from an ESD bias of about 150 V in August of 2023 ( 72118 ) to 58 V now, with the coupling difference between the two setting a factor of about ten (in other words, if we stuck with the old setting the coupling would be nearly ten times worse).  Between January of 2023 and August of 2023, the minimum coupling changed from about 130 V to about 150 V, with the coupling difference between the two settings being less than a factor of two. The second page of the figure is from this August alog, showing the difference in the coupling between then and now. I checked the differences across the break for ETMY, ITMY and ITMX and the coupling differences across the break were not much more than a factor of two, so the change in ETMX, about a factor of ten, seems particularly large, as might be expected for a significant charge change.

TITLE: 06/02 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Lock Acquisition
INCOMING OPERATOR: Ryan C
SHIFT SUMMARY: Currently working on trying to relock the ifo. We had SRM M3 trip again during initial alignment (happened two IA's ago on Friday), and we are at FIND_IR and are having issues finding COMM.
LOG:

14:30 Detector Observing and Locked for 15.5 hours

22:19 Lockloss from earthquake
    - sitting in DOWN while the ground moves
22:30 Started an initial alignment
    - We had SRM M3 trip again (it had tripped Friday afternoon during an initial alignment as well 78163)
23:09 In FIND_IR and can't get COMM beatnote up

Last week I investigated the stray beam hitting the bellows on the spool piece by HAM3. It turned out not to be reflected from the HAM3 viewport as I had first hypothesized, but was reflected by, or originating at PR3.  Figure 1 shows that the shadow pattern indicates that the beam is coming from the HAM2 direction. Figure 2 shows that, at the viewport near where the beam hits, the viewport for the PRM camera, there is an excess of light coming from PR3, suggesting that the outer halo of the beam is visible from that viewport and the beam is coming from PR3. This beam may be slightly clipped by the MC baffle by HAM3 and worth more study.

TITLE: 06/02 Eve Shift: 2300-0800 UTC (1600-0100 PST), all times posted in UTC
STATE of H1: Lock Acquisition
OUTGOING OPERATOR: Oli
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 11mph Gusts, 8mph 5min avg
    Primary useism: 0.05 μm/s
    Secondary useism: 0.10 μm/s
QUICK SUMMARY:

• We're doing an IA following a lockloss from an earthquake (Almost a 24hour lock, 23:24)
• The winds are calming down

Lockloss 06/02 22:19 UTC from earthquake

We are Observing at 158 Mpc and have been Locked for 20.5 hours. Wind has been picking up and is ~25mph at the corner station. Everything is going well.

Sun Jun 02 10:08:03 2024 INFO: Fill completed in 7min 59secs

TITLE: 06/02 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
OUTGOING OPERATOR: Tony
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 3mph Gusts, 2mph 5min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.08 μm/s
QUICK SUMMARY:

Observing and have been Locked for 15.5 hours. There's the back end of a small local earthquake coming through, but we're getting through it fine.

TITLE: 06/02 Eve Shift: 2300-0800 UTC (1600-0100 PST), all times posted in UTC
STATE of H1: Observing at 152Mpc
INCOMING OPERATOR: Tony
SHIFT SUMMARY: Quiet shift, a small EQ and the winds were rising in the last few hours. We've been locked for just over 9 hours.

22:57 UTC Observing

23:10 UTC supereventS240601co

We've been locked for 4:30, the wind has been picking up over the past hour which is bleeding into the 0.03 - 0.1 Hz bandwidth.

TITLE: 06/01 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 152Mpc
INCOMING OPERATOR: Ryan C
SHIFT SUMMARY:  Pretty quiet day with a lockloss that was easy to recover from.
LOG:

14:30 Detector Observing and Locked for 10 mins
15:16 Took us out of Observing to try and optimize sqz (new OPTICALIGN offsets accepted in SDF) (tagging SQZ)
15:24 Back into Observing

18:30 Left Observing to run calibration
19:00 Back to Observing

21:51 Lockloss
    - Needed to intervene to help catch ALSY
22:54 NOMINAL_LOW_NOISE
22:57 Observing

Sheila, Ryan S, Oli

We spent some time yesterday looking at the 05/31 16:45 UTC lockloss, which was caused by a couple of large earthquakes. As the ground started moving more and we got closer to losing lock, DIAG_MAIN was telling us that IMC-REFL_SERVO_SPLITMON was close to saturating (>8V), and we also got some SRM saturations. We wanted to look into what the actual cause of the lockloss was (we weren''t able to confirm that) and see if we could change anything wrt the SRM control loops or IMC SPLITMON in order to make the detector more robust against earthquakes.

We first looked at the length, pitch, and yaw of SRM M3 DRIVEALIGN to see which of the three was contributing the most drive during the earthquake (attachment1). All three have a frequency of around 57mHz. Multiplying the max L/P/Y DRIVEALIGN values reached right before the lockloss by their respective EUL2OSEM values, we find that L was 100,000, P was 52,380, and Y was 7,333, so we will want to offload some of the driving on L.

We also looked into the saturations in IMC-REFL_SERVO_SPLITMON that occured prior to the lockloss (attachment2, attachment3). The IMC-REFL_SERVO_SPLITMON trace shows it saturating multiple times, with the saturations sometimes lasting as long as 3 seconds. We compared SPLITMON to some other relevant channels - I can''t explain why these other channels are relavent, but Sheila said that we might want to talk to Daniel about reducing the load on IMC-REFL_SERVO_SPLITMON.

I looked into how often SPLITMON saturations seem to occur, and they almost exclusively happen when we have high ground motion from earthquakes or wind(attachment4). I found that there have only been two of these ground motion SPLITMON locklosses in O4b (05/14 and 05/31), but before O4b there were many more, usually more than one per month and mostly seen in clumps. I also checked which of these locklosses from the beginning of O4 were accompanied by SRM saturations, and was only able to find 7, with yesterday's being the only one this year.

Ground motion + SPLITMON + SRM saturations during O4 so far:
2023-06-16 11:48 UTC
2023-10-02 00:54 UTC
2023-10-07 08:16 UTC
2023-10-11 01:43 UTC
2023-10-15 04:38 UTC
2023-10-16 03:18 UTC
2024-05-31 16:45 UTC

TITLE: 06/01 Eve Shift: 2300-0800 UTC (1600-0100 PST), all times posted in UTC
STATE of H1: Observing at 149Mpc
OUTGOING OPERATOR: Oli
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 7mph Gusts, 5mph 5min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.09 μm/s
QUICK SUMMARY:

• We just relocked and returned to observing at 22:57UTC
• Everything looks stable

Lockloss @ 06/01 21:51 UTC from unknown cause

We're Observing at 155 Mpc and have been Locked for 6 hours now. Nothing else to note

Terry, Kar Meng

The cavity finesse, beam profile and power transmitted through the crystal seem fine. The conversion efficiency however still needs a bit of attention. At the moment it is almost 30% at 60mW. An extra 5 - 10% would be good. I suspect the phase matching temperature is not quite optimised. I'll lfine tune it Monday.

We went into commissioning at 18:30 UTC to do our Saturday calibration sweep