Today, around 19:13 UTC, I have restarted Hrec to use the new bias file /virgoData/Hrec/Hrec_bias_202508_with50.txt which is based on checkhrec measurements done between July 14th and Aug 25th. This update of the bias file is a follow-up of the observation that, since start of July, the hrec/hinj bias was impacted by the changes that occured on the ITF.
Plot1 shows the residual bias before the restart of Hrec.
Plot2 shows the residual bias after the restart of Hrec.
At the start of the shift, the interferometer just recovered from an unlock likely due to intense wind, and was in Science mode for about 30 minutes. Another unlock occurred at 13:41:19 UTC, GPS 1440423697. After a series of unlocks for the strong wind (50+ km/h) before reaching LOW_NOISE_3 state, at 14:35 UTC the interferometer has been set to Commissioning mode, moving up the scheduled activities. LOW_NOISE_3 recovered at 18:57 UTC, after the calibration activities.
Below, the list of performed activities:
15:35 - Started Measurement of the TF between CAL and Sc channels, and of PCal sensing delays. Concluded at 15:48 UTC
16:20 - Measurement of actuators response for PR and BS mirrors. Issue with DET_MAIN shutter closed when setting CALIBRATED_PRWI. Restored by putting DET_MAIN back to INIT, and restarting the calibration procedure. Concluded at 17:17 UTC
17:20 - Measurement of actuators response for NI,WI mirrors. Concluded at 18:40 UTC
15:48 - TCS, Cifaldi check of the powers. Operation competed at 16:18 UTC
19:13 - CALI, Verkindt: Hrec bias updated.
The interfermeter unlocked again at 19:30:51 UTC, GPS 1440444669, when a hailstorm hit the site, and, given that we were already 30 miutes past the end of the Commissioning slot, we decided to postpone the Scattered Light calibration activity by van Haevermaet. The interferometer was set beck to PREPARE_ASCIENCE mode (and AUTOSCIENCE_ON)
Other events to report:
Guard tours (time in UTC)
Since the input beam was quite decentered on the ITMs, we translated the PR both horizontally and vertically to better recenter it (monitoring at the same time its position on the BPC quadrants).
The intervention solved the issue as shown by the latest UPV run: https://scientists.virgo-gw.eu/DataAnalysis/DetCharDev/online/upv/2025/20250828/last_day_1440280822-1440367222/V1:Hrec_hoft_16384Hz/perf/vp.html
ITF found in LOW_NOISE_3 and in Science Mode. It unlocked at 3:57 UTC, but the ITF kept systematically unlocking at LOCKING_CARM_MC_IR. An issue highlighted by the DMS was a strong oscillation on the WI F7: while investigating we found that the data were abnormal (see attached plot).
With the support of Gherardini we opened the F7 loops and reload the DSP, which seems to have fixed the issue. Relock in progress.
Guard Tour (UTC)
22:28 - 22:52
1:02 - 1:24
3:27 - 4:00
DAQ
From around 14:00 UTC the signals related to INJ and DET ACS weren't avaiable anymore from DMS. After restarting the process BACnetServer at 21:01 UTC they were acquired correctly again.
13:00 UTC ITF found in SCIENCE
14:56 UTC ITF in ADJUSTING - WI Etalon Servo Disabled/re-enabled to perform WI power supply swap (#67582 Dattilo, Zaza)
15:25 UTC ITF DOWN
16:15 UTC ITF in SCIENCE
Guard Tours (UTC)
18:02 - 18:50
20:28 - 22:50
The time pattern and magnetic witness point to a noise from the power supply of the heating belts, as evidenced by Bas in O3: https://logbook.virgo-gw.eu/virgo/?r=48521
sorry I missed the previous post, pointing to the same problem. The time pattern is clear.
However, consulting with Federico and Vincenzo: the cause is likely the power supply, whose fans are old and do not cool down enough, the power supply goes in protection ad switches on/off.
The suggestion is first inspect and then replace.
These glitches look similar to something we’ve already seen in April 2024: #64114.
At the beginning of the shift, the interferometer has been found relocking, with AUTOSCIENCE_ON. Succesfully back to LOW_NOISE_3 state at 5:29:12, and SCIENCE mode at 5:32:12 UTC. Operational status maintained throughout the entire shift.
Their frequency distribution seems to go from around 15 Hz up to almost 60 Hz.
First glitch is most likely a 25-min glitch. (Picture shows the whitened spectrogram of Hrec_hoft_20000Hz)
These glitches (I guess these are the same... and 33 Hz or so might be the energy baricenter?) seems to have a precise periodic pattern, see the attached.
Last night's daily UPV run points V1:ENV_WI_MAG_{N/V/W} as witnesses for those glitches. Compare before and after applying these vetoes.
As noted in https://logbook.virgo-gw.eu/virgo/?r=47107 a peak at 41.3 Hz was excited when doing a sweep-shaped shaking of the WE chamber, during O3.
With a deeper examination of the Hrec data during the WE tapping sequence we notice a characteristic pattern that got excited when tapping from some of the locations.
The pattern, shown in the attached figures, consists of a family of narrow spectral peaks at precise frequencies (Hz) :
This pattern gets excited when tapping on locations at the tower chamber, not from CT locations. Most peaks are more excitable when tapping on HR side, but the 88 Hz is much louder in hrec when tapping the viewport on the AR side (the 41 Hz has a similar behaviour). Some coherence with accelerometer is present for all of them, pointing to a mechanical structure attached to the tower that gets excited by the tapping.
Tapping on the AR viewport also excited a clear peak at 167Hz which clearly associates to a corresponding peak in the AR flange accelerometer, as already noted in the previous.
Other notes:
Figure 1. A new family of glitches started on Sunday around 15:30 UTC. These glitches are loud and frequent, and look to be around 33Hz.
Figure 2. These glitches are continuing during last night, so this problem is still present.
Last night's daily UPV run points V1:ENV_WI_MAG_{N/V/W} as witnesses for those glitches. Compare before and after applying these vetoes.
These glitches (I guess these are the same... and 33 Hz or so might be the energy baricenter?) seems to have a precise periodic pattern, see the attached.
Their frequency distribution seems to go from around 15 Hz up to almost 60 Hz.
First glitch is most likely a 25-min glitch. (Picture shows the whitened spectrogram of Hrec_hoft_20000Hz)
These glitches look similar to something we’ve already seen in April 2024: #64114.
The time pattern and magnetic witness point to a noise from the power supply of the heating belts, as evidenced by Bas in O3: https://logbook.virgo-gw.eu/virgo/?r=48521
sorry I missed the previous post, pointing to the same problem. The time pattern is clear.
However, consulting with Federico and Vincenzo: the cause is likely the power supply, whose fans are old and do not cool down enough, the power supply goes in protection ad switches on/off.
The suggestion is first inspect and then replace.
The intervention solved the issue as shown by the latest UPV run: https://scientists.virgo-gw.eu/DataAnalysis/DetCharDev/online/upv/2025/20250828/last_day_1440280822-1440367222/V1:Hrec_hoft_16384Hz/perf/vp.html
ITF found in LOW_NOISE_3 and in Science Mode. It kept the lock for the whole night but unlocked at 4:43 UTC.
Relock in progress.
Guard Tour (UTC)
20:59 - 21:36
23:05 - 23:43
1:07 - 1:42
3:27 - 4:01
13:00 UTC ITF found in LOCKED_ARMS_IR - TROUBLESHOOTING
13:30 UTC NEB green laser recovery following a loss in power (see pic. 1) (Casanueva, De Rossi)
13:30 UTC CEB Suspension Vertical System Centering (#67568) (Boschi, Razzano)
14:12 UTC stol02 processes reboot (#67567) (Salconi, Kraja, Masserot)
15:14 UTC NI TCS bench thermalization (Gherardini, Melo)
16:04 UTC NI TCS end of maintenance. As suggested by Nardecchia, we waited one hour (more or less) to allow the system to adjust before trying to lock
16:58 UTC ITF in CARM_NULL_1F. After aligning west arm, PR and SR and reaching the state, SDB2_B1p_DC signal was too high (Bersanetti)
17:38 UTC NI DAS CO2 laser (outer ring) first power adjusting step (Nardecchia)
18:26 UTC second power adjusting step (#67571) (Bersanetti, Nardecchia)
20:36 UTC ITF in LOW_NOISE_3 - SCIENCE
Guard Tours (UTC)
18:04 - 18:37
20:58 -
After the activity on the NI CO2 bench, the ITF successfully relocked at CARM NULL 1F on the first attempt at 16.58 UTC.
However, we observed that the power on B1p was too high (0.03 mW) to proceed with the lock acquisition, so we started tuning the NI DAS to reduce it.
Step 1 (17:38 UTC): Decreased outer ring power
NI CO2 PICK OFF: 0.55 W → 0.52 W
Positive effect on B1p
Step 2 (18:26 UTC): decreased outer ring power
NI CO2 PICK OFF: 0.52 W → 0.49
Negative effect on B1p
Step 3 (19:04 UTC): Increased outer ring power
NI CO2 PICK OFF: 0.49 W → 0.51
Step 4 (19:20 UTC): Increased inner ring power
NI CO2 PICK OFF: 0.51 W → 0.522
Once the B1p power reached 0.02 mW, we resumed the lock acquisition.
The ITF relocked in LN3 at 20:36 UTC.
Lock acquisition procedure is still to be verified.
This afternoon, Suzanne and Fabio adjusted the M3 mirror to restore the pre-mirror replacement alignment.
The comparison of the DAS before and after the mirror replacement is shown in Fig. 1.
Work on the bench was completed at 15:55 UTC.
The correct powers were recovered, and all flip mirrors were re-opened at 16:04 UTC with standard powers.
This morning from about 10:45 to 12:00 LT we entered the DET lab to perform measurements of air speed velocity in different locations inside the lab. The used tool is a hot wire anemometer (sauermann KIMO VT110) by Davide. The scope is to get a quantitative idea of how the air moves inside the lab. We took measurements with the air conditioning on in REDUCED mode from 10:45 to 11:15 LT, then with the air conditioner on in NORMAL mode from 11:40 to 12:00 LT. The air conditioner was set in Nominal flux mode from 11:36 to 12:17 LT.
We took measurements at approx. 20cm from the air inlets in the ceiling, the two air outlets in the walls, around the covered EDB and in a pair of positions in the EDB room at beam height. When in REDUCED mode we measured air speeds in the range 0.05 to 0.35 m/s close to the inlets, 0.05 m/s and 0.02 m/s close to the two outlets (respectively the one close to the entrance door and the one in the SW corner), from 0.02 to 0.15 m/s around the EDB, 0.02 m/s in the room close to SDB2 chamber doors. When in NOMINAL mode air speed values close to the inlets and around the EDB roughly doubled, but also were significantly oscillating (by a factor 3 or so) on the time scale of 10 seconds or so. At the two outlets the air speed increase was more substantial and stable (no oscillation observed), reaching 0.3 m/s near both.
Additionally, when HVAC in NOMINAL mode we measured a value of 0 m/s inside the SQZ area (only one position measured).
The air flow seems to slow down going from the East wall towards the West, the larger air flux is on the lab East side, as it seems reasonable since the 4 air inlets are placed on the ceiling along this wall.
We shall add a map reporting all measured values.
Figures show values of HVAC fans speed, air fluxes in/out of the DET lab, temperature and microphone RMS, during the measurements time.
Due to saturation of BS and WI F0 vertical coils we recenter the vertical position of the filters.
Start at 15:40 LT
End at 17:00 LT
