J. Kissel
IIET Ticket 31266

Conversations are still brewing about what to do about DuoTone timing signals showing up in DARM -- presumably through the OMC DCPD's ADC card (see LHO:77579). Recall that we've narrowed down the coupling mechanism to direct channel-to-channel cross coupling within the ADC (see LHO:78238). As such, one of the options on the table is to reduce the amplitude of the DuoTone timing signal, which is using 1/4 of the ADC channel's range at 5 [V_pp], rather loud, IMHO (see LHO:78218). 

Daniel and Erik did a whole bunch of work at the start of O4 to get the front-end-code computed ADC timing measure more accurately reporting and answer with a better algorithm in the front-end (see LHO:67693 and LHO:67545), so I figured I show the trend of a few important front-end's answers, since I haven't seen such a trend:
    (1) the h1omc0 segregated IO chassis which houses the GW DCPDs,
    (2) the h1lsc0 computer which *used* to house the DCPDs prior to O4.
    (3 & 4) the two end-station ISC computers which house, among other things, the PCAL systems.

The answers from the long-term trend: 
    (1) 0.12 +/- 0.035 or +/- 0.08 [usec]
    (2) 7.05 +/- 0.031 or +/- 0.06 [usec]
    (3) 61.6 +/- 0.15  or +/- 0.31 [usec]
    (4) 61.6 +/- 0.15  or +/- 0.31 [usec]
where I'm eye-balling (via y-cursor at least) the long-term trend of the mean, the middle of the max/min excursions, and the worst of the max/min excursions.
These answers (the means) are all expected, but it's good to have some numbers on the max / min excursions, which are, presumably, noise.

Zoom in closer, one can see on the minute time scale trend of a gravitational wave event, the estimation of the timing error is about as precise.
     

R. Short, F. Clara

In the ongoing effort to mitigate the 9.5Hz comb recently found to be coming from the PSL flow meters (alog79533), this afternoon Fil put the PSL control box in the LVEA PSL racks on its own, separate 24V bench-top power supply. Once I shut down the PSL in a controlled manner (in order of ISS, FSS, PMC, AMP2, AMP1, NPRO, chiller), Fil switched CB1 to the separate power supply, then I brought the system back up without any issues. I'm leaving the ISS off for now while the system warms back up. I'm leaving WP12051 open for now until enough data can be collected to say whether this separate supply helps the 9.5Hz comb or not.

Please be aware of the new power supply cable running from under the table outside the PSL enclosure to behind the racks; Fil placed a cone here to warn of the potential trip hazard.

FAMIS 21224

pH of PSL chiller water was measured to be just above 10.0 according to the color of the test strip.

FAMIS 21188

The PSL was taken down last Tuesday as part of Jason and Fil's comb hunt (alog79533), which shows in basically every trend six days ago.

The ISS was not turned back on when the PSL was brought back up last week, so Jason enabled it this morning, which explains the lower PMC transmitted power over the past week or so. However, even with the ISS now on, the PMC is putting out ~1.6W less power compared to before it was unlocked last week.

The FSS TPD has been trending down over the past several weeks and alignment looks poor on the camera, so sometime today or tomorrow I'll touch up the RefCav alignment.

About a week ago the PSL enclosure main-room Axis camera image froze mid-frame twice over two days in a row on the LVEA FOM machine (lveapslfom) but not on the control room FOM (nuc21).

Last night both the enclosure anti-room and main-room images on the control room FOM froze mid-frame but the LVEA FOM was fine.

In all cases I remote-desktopped to the machine and reloaded the web page to clear the error.

Mon Aug 19 08:09:15 2024 INFO: Fill completed in 9min 11secs

TITLE: 08/19 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 4mph Gusts, 1mph 5min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.07 μm/s
QUICK SUMMARY:

Vacuum pressure in BSC3 around 2.04e-07 (need to be around 8.8e-8), so probably no gate valves today. Over the weekend an earthquake from Japan tripped the ISI watchdogs for ITMY, BS, ETMX, and ETMY. Those have been untripped by TJ.

FAMIS26004

Same as for the last time this was run (alog79474), the following seem elevated:

• ITMX St1 V1
• ITMY St1 V2
• ETMY ST1 H2

FAMIS26283

Laser Status:
    NPRO output power is 1.831W (nominal ~2W)
    AMP1 output power is 64.55W (nominal ~70W)
    AMP2 output power is 138.3W (nominal 135-140W)
    NPRO watchdog is GREEN
    AMP1 watchdog is GREEN
    AMP2 watchdog is GREEN
    PDWD watchdog is GREEN

PMC:
    It has been locked 5 days, 20 hr 28 minutes
    Reflected power = 20.62W
    Transmitted power = 105.1W
    PowerSum = 125.8W

FSS:
    It has been locked for 1 days 19 hr and 20 min
    TPD[V] = 0.5346V

ISS:
    The diffracted power is around 3.1%
    Last saturation event was 0 days 0 hours and 0 minutes ago

Possible Issues:
        AMP1 power is low
        PMC reflected power is high
        FSS TPD is low
        ISS diffracted power is high

I've lowered the alarm level for PT120B (BSC2) from 2.0e-06 to 2.0e-07. Two day trend of PT120 attached shows last nights excursion

Config:

Channel name="H0:VAC-LY_Y1_PT120B_PRESS_TORR" low="1.0e-10" high="2.0e-07" description="VE gauge, PT120B BSC2 CC"

Sun Aug 18 08:08:47 2024 INFO: Fill completed in 8min 43secs

(Richard M., Dave B, Gerardo M.)

While at home I Noticed that the pressure trend for PT120 (BSC2 pressure gauge) had a sudden rise on pressure, see trend.  Called Richard M. and we tried to diagnose the system from of site, instead I decided to drive over to the site and diagnose the situation.  I found two turbos off, and the scroll pump for the turbo at XBM ("X" beam manifold) was still running, the other one (YBM) was off.  Closed the isolation gate valves for both systems, then proceeded to do a restart for both units, no issues encountered during restart, both of the turbo pumps reached full speed very quick, and after waiting for some time, 15 minutes, set points were set, then the system was valved in to the main volume.

Checked all other turbo pumps, output mode cleaner tube, HAM6 and HAM7, they were all running and doing good.

We have 4 aux carts pumping on different systems and they were good too.

I checked all ion pump controllers and they were good.

Still we do not know what caused the two turbos to power off, we will look further into it.

Leaving site now.

Sat Aug 17 08:09:27 2024 INFO: Fill completed in 9min 23secs

TITLE: 08/16 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: None
SHIFT SUMMARY: Got the ion pumps pumping today, so the pressure has gone down quite a bit. Also did a quick check of AS_C and the fast shutter using single bounce (79575). The IMC is LOCKED, and ITMs are MISALIGNED.

LOG:

14:30 In Corrective maintanence, IMC in OFFLINE
    - I adjusted the OPTICALIGN OFFSET values for MC1,MC2, and MC3 until the driftmon values were back to what they had been yesterday before the computer crash. Then I took IMC_LOCK to LOCKED and it caught easily.
16:30 Ion pumps turned on
18:00 - 19:00 Single bounce measurement                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            

Evan Goetz, Alan Knee, Ansel Neunzert (on behalf of line list contributors, see LIGO-T2400204)

Summary:
Version 1 of the lines and combs list of non-astrophysical artifacts yields insights into the O4a H1 data about long duration narrow spectral artifacts. In summary, H1 data has nearly 7x more of these artifacts than L1, mostly due to the much higher proliferation of comb artifacts. H1 data also suffers from a large number of narrow artifacts in the ~100 Hz bands near test mass violin resonance harmonics, usually during times of rung up violin resonances. Without careful handling of the data in frequency bands near the violin modes, nearly 18% of the 10 Hz - 2 kHz band is contaminated, though more careful handling results in about 6% of the band being contaminated (roughly equivalent to L1). The L1 detector does not suffer from these same artifacts.

Details:
After compiling a list of vetted, non-astrophysical artifacts into the version 1 lines and combs list for O4a, we extracted some statistics for each detector in order to compare and contrast the data quality from this perspective, and to determine which of the artifacts are most problematic for long duration narrowband searches (CW or narrowband directed stochastic searches).

New for this observing run, we have two new features for the lines list: 1) artifacts with known time variation (turn on/turn off) where we can establish reasonable metrics for their presence in the data we also provide a segment list for times those artifacts are present; 2) a new type 3 artifact that is not simply a narrow frequency band for a single artifact, but rather a band (typically 1 Hz or larger) with many narrow artifacts degrading the data quality within the band.

Type                         H1        L1
-----------------------------------------
Total number of artifacts   1721      251
Number of vetted combs        26       16
Comb lines                  1510      168
Type 3 artifacts              29        0
Vetoed band percentage
(excl. type 3 artifacts)    5.8%      6.3%
Vetoed band percentage
(incl. type 3 artifacts)   17.9%      6.3%

Most problematic H1 artifacts:
1) Type 3 artifacts: non-stationary line artifacts impacting ~100 Hz bands around TM violin resonances - partial understanding of some of these artifacts due to calibration line mixing with violin resonances (future aLOG), but not all artifacts are understood
2) 9.5 Hz comb triplet: comb of line triplets present from 10 Hz to 2000 Hz (seen weakly at L1) - potential cause identified in PSL flow sensors (LHO aLOG 79533)
3) ~11.11 Hz comb seen in both H1 and L1 - not understood. It was also seen at H1 in O3.
4) ~11.9 Hz comb seen in both H1 and L1 - not understood. See also checks on different changes. Seen also in O3 H1 data.

H1 artifacts that have been mitigated:
1) Hartmann wavefront sensor (HWS) comb mitigated near 1 Hz, near 5 Hz, and near 7 Hz combs
2) OM2 heater driver comb mitigated ~1.66 Hz comb (also 1.1086 Hz briefly appearing)

Ongoing detailed analysis (future aLOG) of the violin mode region contamination indicates that at least some of the lines are calibration line + violin mode mixing. We are not yet sure whether this explains all the contaminated time periods in O4a, nor to all the contaminated lines, and we have not done a systematic comparison with L1. However, at the overview level, the mixing of calibration lines and violin resonances seems much worse in H1 than in L1. Perhaps this is somehow related to the new signal readout chain installed ahead of O4 that is different from the readout at L1. The number of lines also should instill some caution into further efforts to put additional calibration monitoring lines into the DARM control loop as the added lines would greatly increase the number of artifacts in the spectrum. This needs to be solved before further lines are added.

We anticipate further understanding of the O4a data with continued investigation, so the number of artifacts known to be non-astrophysical may go up.

Late entry from yesterday:
- The controllers of IP1, IP2, IP3, and IP14 ion pumps were replaced with the old rebuilt Varian controllers, in order to prepare for valving the ion pumps in (IP4 still has its original Varian controller). This is the reason why these Ion pumps turned red in the vacuum MEDM screen
- The new instrument air scroll compressor came online: it was valved in, and the Kobelco was valved out. Huge kudos for Tyler and Eric and the FAC team!

Today's activities:
- The large Ion pumps were valved in. At first IP1 and IP2 - these pumps have Chevron baffles, so the immediate gas rush was somewhat mitigated by valving these 2 in first. Then IP3 and IP4. Then, after a few hours IP14 (HAM6)
- The pressure immediately went down from 3.7E-7 to 1.7E-7, and it is dropping. The ion current in the IPs has not started to go down just yet
- The Kobelco was switched off

The pressures:
- Corner (PT-120): 1.6E-7 Torr
- HAM6: 3.4E-7 Torr
- HAM7: 9.4E-8 Torr

As soon as the pressure according to PT-120 reaches 8E-8 Torr, the gate valves will be opened. HAM7 and the filter cavity will follow after a few hours.
Huge congratulations to Gerardo and Travis, and everyone who helped the vacuum team to achieve this fast pumpdown, and that the plan of opening up on Monday (19th) is still on.

Oli P, TJ S

Single Bounce AS_C level

To check that we can get light through to HAM6, we brought the IFO to the same alignment as in alog79193, where they also had HAM5,6 HEPI locked. We started with the fast shutter closed. With alignments the same we went into a single bounce configuration with ITMY aligned and went up to 10W. There was no light on AS_C initally, so Oli had to move SR2 about 200urads before there was light on the sensor. SR2 moved about 60urads to center on AS_C. With AS_C centered, H1:ASC-AS_C_SUM_OUTPUT was at 0.0078 vs the 0.0045 reported on July 17 reported in the linked alog above (73% increase). We ran into some P motion when we turned sensor correction on, but maybe this is expected while we have some HEPIs locked. The AS Air camera had the slightest bit of a spot on the top left corner of it when we were centered.

Fast Shutter Test

While centered on AS_C we opened the fast shutter. We immediately saw light on AS_A and AS_B (1600 and 2000 counts respectively). We closed the shutter and it went away. 1st attachment

Alan Knee, Camilla Compton, Evan Goetz

We changed the SQZ ADF frequency from 322 Hz to 10 kHz where it should not impact long duration searches (figure), using the command 'python /opt/rtcds/userapps/release/sqz/h1/scripts/ADF/setADF.py -f 10000'. This line appeared in DARM during O4a when it was set to 1300 Hz. It was moved from 1300 Hz to 322 Hz around 1397588061 (2024/04/19 18:54:03 UTC, figure), and was visible in Fscan spectra in O4b (figure).

This line was previously turned "off" on 2024/04/04 (see 76962), but was still visible in DARM (at reduced amplitude) due to the RF driver being left on. You can see the change in behaviour in the attached line height plots. The first shows the height of the 1300 Hz line during April 2024, where the line is at first "on", decreases in strength after April 4, and then disappears on April 19 when it was moved to 322 Hz. The second shows the height at 322 Hz, which appears on April 19.