DRAFT - REPORT  IN PROGRESS - will be finalized at the end of the shift

ITF found in LOW_NOISE_3 and in Science Mode. ITF still locked.

ITF found locked with Autoscience active. It remained locked for the whole shift.

ITF found in Science and kept the lock for the whole shift, BNS Range ~50Mpc

• 14:40UTC - 14:52UTC Troubleshooting mode, Investigations on the leak in CEB compressed air system carried out by Soldani, Francescon and Erbanni

Guard Tours (UTC):
18:00 - 18:40
20:00 - 20:36

Yesterday the SOA (semiconductor optical amplifier) of the west end broke (SOA- 542-DBUT-PM, test report attached). The input fiber seemed to be burnt (see attached photo) but the company told us that they start to paint it in black to mark the higher PER ( polarization extinction ratio) port . The current setpoint was at 85mA (#65776 ), we verified that it had been plugged correctly (yellow=input, red=output) and the power at the input of the SOA was 2mW (which is consistent with the one measured back in 2020 #49407).

As a patch since we do not have a spare SOA, we removed the PSTAB photodiode and set the offset to have the maximum in transmission of the fibered AOM, thus obtaining 0dBm in input of the 2W amplifier (which is sufficient for the restart).

Diego commented the check on the PSTAB in the automation and I shelved the PSTAB in the DMS.

Discussing with the company we defined some possible tests to perform:

1. One of the likely reasons of failure could be the thermal overheating of the SOA module. It gets overheated and the driver shuts down the emission. The SOA module itself could be ok and not damaged at all.
2. Check the mechanical contact between the SOA module bottom and the mount ( if possible use some thermal paste between SOA module and the mount).
3. Try to swap Pilot-4 controller used with K004997 with a different one and try repeating the test, making sure all cable connections are secure and electric cables are not damaged.

The ITF is currently in troubleshooting, and the WE ALS green light is still off. Below is the list of checks performed:

• Possible leak of compressed air in the CEB (D. Soldani, L. Francescon)
• Sled source replacement  at NEB (E. Majorana)
• Investigation of the WE ALS green light status (C. Derossi, M. Mantovani)
• Closed SDB1 shutter (M. Delaurentis, D. Bersanetti) 
• ITF CONDITIONS tests (D. Bersanetti)

11:10 UTC: ITF is back in relocking. There is slightly higher sea activity, making it a bit difficult to complete the lock. After several attempts, I had to misalign the SR by 1.5 µrad in the Ty+ direction. At 14:02, the ITF is back in SCIENCE mode.

Being the ITF down with DIego we decided to close SDB1 FI shutter.

I did it with -6700 steps. Attached the ipcam34 start and end screen shots

Today I improved the STALL detection from ITF_CONDITIONS towards ITF_LOCK and ITF_STATUS. I added to the node, only in the main() method in DOWN, the same code which is widely used in the unstall_nodes decorator, without using the decorator itself to avoid issues when ITF_CONDITIONS is not managing the two.

After trying to unstall both nodes, what is done is asking both nodes the states that they jumped to on their own in occasion of an unlock (so DOWN and NOT_LOCKED respectively); at this point it is needed (in the run() method) to ask again the target state for ITF_LOCK, which will be the last Science-allowed state it was into. For this reason, just before putting Science mode, the ITF_CONDITIONS node also saves in the configuration file the name of such state (in the same way as the two boolean flags described in a previous comment), so that once in DOWN such state can be loaded from the configuration file and asked again to restart the lock acquisition, hopefully getting rid of the stalling issues observed a few nights ago.

The ITF_CONDITIONS node has been reloaded but I will need a couple of full lock acquisition cycles to understand if everything is fixed now or if additional debug is needed.

We added in the INIT and DOWN states of ITF_LOCK a cm command to set the WARNING log level to SatServer.

Today I added the same functionality to the WARM_LOCK node, and reloaded it.

Today I added the same functionality to the ALS_NARM node, and reloaded it.

ITF found in LOW_NOISE_3 and in Science Mode.
At 16:11 UTC the flag mean_VAC_VALVEBIGNI__COMPRESSAIR_10 went below threshold, reporting an issue with the NI Valve which could close in case of further decrease of value. At 16:17 UTC I set the ITF in TROUBLESHOOTING Mode to allow Pasquatetti and the Vacuum team to investigate the issue in the Central Building.
At around 16:50 UTC the crew exited the building to investigate inside the Technical building, at 16:55 UTC the ENV Team started the planned Noise Injections (see report #65839). 
At 17:27 UTC I entered the WE Building to investigate the missing ALS green beam (see operator report #65837). I contacted van De Walle and, following his instructions, I attempted to restart the SOA Driver. Unfortunately the devide turned off even at low currents, and seems to stop working by itself after few minutes. No further actions were possible at that moment, at 17:40 UTC I put the device with zero current and left the building.
In parallel, De Laurentis verified the green laser of the SQZ (see report #65844), and left the Central building at 18:15 UTC.
ITF back in Science Mode from 18:19 UTC. Strong wind activity during the last part of the shift.
The ITF unlocked at 21:49 UTC, due to the impossibility to relock the ITF I left the ITF in LOCKED_ARMS_IR.

Guard Tour (UTC)
18:00 - 18:29
20:30 - 20:56

Values compared with 6June 2023 (5844)

• GR    input LMB                  34,90 mw   
• GR    input AOM                 34,11 mw    (45,5 mW) 
• GR    input FI/double pass   13.7  mW   (27.1 mW)
• GR    output FI                12.96 mW    (25.5 mW)

We injected acoustic noise in WEB using the setup and settings described in https://logbook.virgo-gw.eu/virgo/?r=65823

Start GPS: 1418662332  19 Dec 2024 16:51:54 UTC  (19 Dec 2024 17:51:54 CET)

End GPS: 1418663445

It enhanced in hrec a broad noise around 120 Hz. Qualitatively this is different from what observed during the similar injection of October 31 (ttps://logbook.virgo-gw.eu/virgo/?r=65438).

Coupling functions to be computed and compared.

I found ITF in SCIENCE; It remained locked for the whole shift.

Other
06:22 UTC ALS green at WE is off

Other
( - ) At the next unlock reload ITF_CONDITIONS

ITF in Science mode for all the shift.

Guard tours (time in UTC)

22:05-22:36; 0:12-0:43; 2:10-2:40; 4:13-4:43

Other
( - ) At the next unlock reload ITF_CONDITIONS

Fabio reports that

• the virgoLog area is full at 90% triggering a red flag in the DMS
• and that the rate increased since November 11th

After some investigations, we found that the culprit was the SatServer : clicking on the button "Activate WARNING logging" allows to reduce a lot the log rate : operation performed at 2024-12-18-21h30m52-UTC .

The biggest SatServer log files have been moved into the data/dev/logs/VirgoOnline/SatServer directory to recover a correct usage of the /virgoLog area

The ITF unlocked from science at 15:33UTC, it relocked at the first attempt and science mode started at16:20UTC.

- guard tours (UTC):
18:36 --> 19:06
20:11 --> 20:41

Other
the VIRGOLOG area is exceeding the 90% of space, the rate started to increase on the 11th of November because of the SatServer log set in "INFO logging" Alain set back the "WARNING logging" level.

ITF found in LOW_NOISE_3 in SCIENCE mode. 08:40 UTC ITF unlocked. 09:23 UTC ITF back in SCIENCE. 12:57-13:01 UTC ITF in ADJUSTING, L. Francescon closed the valve for SQB2 to isolate the tower as requested by SQZ crew. ITF left in SCIENCE.

Yesterday morning, during the maintenance we checked the status of the neovan chiller. Despite a small increase in temperature in the last week, the chiller flow was quite low. We then decided to change the filter with a clean one and swap the water cables (thus inverting the flux). Thanks to this, we recover a much better flow (as a reminder, we do not have online data from the chiller), and a result we decreased the NEOVAN head temperature by more than 1⁰C (see fig. 1).

Since yesterday, the temperature is stable as well as the other ISYS channel (in particular, PSTAB rms improved quite a lot compared to the last days, see fig. 2 too).

The aim of the shift was to perform a scan of the MICH_SET to see if that influences the optical spring effect we see in the MICH2DARM coupling, which differs from the optical spring in the DARM transfer function and also to test a new CARM2DARM Subtraction filter.

First we performed the following injections and MICH_SET changes:

• Noise injection at MICH_SET = 0, GPS time: 1418484683
• Move to MICH_SET = 2 at 15:50:50 UTC
• Noise injection at MICH_SET = 2, GPS time: 1418486005
• Move to MICH_SET = 6 at 16:05:10 UTC
• Noise injection at MICH_SET = 6, GPS time: 1418486951
• Move to MICH_SET = 14 at 16:26:50 UTC
• Noise injection at MICH_SET = 14, GPS time: 1418488135
• Move to MICH_SET = 26 at 16:42:35 UTC
• Noise injection at MICH_SET = 26, GPS time: 1418489335
• Move to MICH_SET = -6 at 17:17:10 UTC
• Noise injection at MICH_SET = -6, GPS time: 1418491637
• Move to MICH_SET = -14 at 17:38:00 UTC
• Noise injection at MICH_SET = 0, GPS time: 1418492441
• Move to MICH_SET = -26 at 17:49:10 UTC

Then the interferometer unlocked when we were close to MICH_SET = -26. We haven't been able to determine whether the MICH offset was the cause or if there was another problem.

In Fig. 1 the DARM and MICH2DARM transfer functions are shown for the different offsets. It is clear that the MICH_SET increases the OS frequency for higher offsets (14, 26). It is also difficult to judge whether the effect is symmetrical. The total offset has to be considered since a the loop for the RIN also adds an offset which is not included in MICH_SET (but it is in MICH_SET_TOT). This offset was roughly 4 and when adding this to the MICH_SET values in the plot, the -14 point and +6 point are -10 and +10 in total MICH offset, and a small change in the OS seems to be happening which is roughly similair for both. The measurement at -26 MICH_SET would have helped to confirm the symmetry, but since we only had half an hour left before the end of the shift and we weren't sure whether the high MICH_SET caused the unlock, we decided against measuring this point.

We were mostly interested in determining whether the MICH_SET affected the OS effect in MICH2DARM but not in DARM transfer function to see if this was the cause for the fluctuating alpha filter. In Fig. 2 the alpha filter for the different MICH_SET is shown. Particularly in the phase behaviour it is clear that the MICH_SET indeed affects the alpha filter and particularly the differential optical spring effect between the DARM and MICH2DARM transfer function, as the phase behaviour shows a clear increase in phase from the -14 offset to the +26 offset, also indicating that this effect is not symmetrical around a zero offset. Further analysis and interpretation of the data is still needed.

After the unlock we moved to the CARM2DARM Subtraction filter. The subtraction had been left off since it wasn't working properly. After analyzing the latest injection, a new filter was fitted (see Figure. 3) on the most recent injection (december 2nd). We implemented this and the result is shown in Fig. 4, with purple no subtraction, red subtraction with gain = 1, and blue the subtraction with gain = -1. After flipping the sign we managed to get roughly an order of reduction in CARM noise in DARM, so we left the filter on with the gain = -1. 

After we concluded the work we left the interferometer in science mode.

ITF unlocked just at the beginning of the shift (21:58 UTC); after the unlock ITF_LOCK went in STALLED blocking the automation. To restore it I had to put in "STOP" (remove Autoscience) from ITF_CONDITIONS. The autoscience was then reactivated at 22:07 during the next lock acquisition. After one failed attempts (B1p and B4 galvos not closed) the ITF was relocked and Science mode automatically set 23:01 UTC.

ITF unlocked after 13minutes, at 23:12 UTC and again ITF_LOCK went in stalled (same as before); ITF relocked and Science mode automatically set at 0:00 UTC. I was I contact with Diego so from 0:09 UTC to 0:13 we exited from Science mode to reload some modifications to ITF_CONDITIONS.

ITF unlocked at 3:55 UTC and again we had the same problem with the automation; at this point I removed the Autoscience. The ITF relocked and at 4:42 UTC I set Science mode.

DET

At 23:22 UTC B1p_QD1 galvo opened and closed during lock acquisition.

ALS

At 4:12 UTC, during the lock acquisition, I manually raised the NE flip mirror from VPM.

Guard tours (time in UTC)

22:12-22:42; 0:13-0:43; 2:00-2:40; 4:11-4:41.

At the beginning of the commissioning shift I reloaded SQZ_MAIN, so it went in this "loose" SQZ_LOCKED_NO_FC configuration.

I also set the variable sqz_debug = True in ITF_LOCK.ini, so any request to go to LOW_NOISE_3_SQZ will be rejected and the automation will fall back to LOW_NOISE_3.