Reports of 58368
Virgo Runs (ER16)
gherardini - 14:59 Sunday 14 April 2024 (63962) Print this report
Operator Report - Morning shift
This morning the ITF unlocked once (10:21UTC) because of PR trip, it not saturated the actuation but the ITF unlocked anyhow, relocked at the first attempt; adjusting mode from 7:18UTC to 7:27UTC to reduce the MC IP corrections.

- guard tours (UTC):
5:01 --> 5:39
7:01 --> 7:30
9:06 --> 9:33
11:01 --> 11:40
Images attached to this report
AdV-COM (AdV commissioning (1st part) )
ruggi - 10:03 Sunday 14 April 2024 (63961) Print this report
Comment to PR trips (63935)

This is a summary of the PR trips occurred recently.

SInce the beginning of O4, almost 3 days, we had 15 trips. At least ten of them would have unlocked, but the feed-forward prevented it. Only one unlocked the ITF: it was the smallest one, almost invisible in PR_F0_TY, but anticipated by the usual fast glitch on the accelerometers as all the others. Its impact would have been null, but the anti-trip applied by feed-forward produced 6 V of locking correction, enough to unlock.

Considering that the correction resulting from the largest trip was 5 V, it has been decided to reduce e little bit the amplitude of the back action. After this modification, the largest trip arrived at 5.5 V of correction and the ITF survived.

It is clear that we are at the limit and there is the possibility of an unlock both with the large and the small trips. So far we have been lucky and we can hope that things will continue like that, but it would be better to have something a bit more robust. The variable back action, based on a measurement of the foreseen amplitude of the trip, seem a feasible strategy, but needs to be validated on the machine.

Images attached to this comment
AdV-SAT (Short SAs Upgrade (MC,IB,DB) Installation)
ruggi - 9:33 Sunday 14 April 2024 (63960) Print this report
Sa_MC_F0_COIL_H1 reduction

As reporter by Francesco, Sa_MC_F0_COIL_H1 was going towards the saturation. The reduction of the correction by the motors has been done this morning, putting in Adjustment for a few minutes.

Virgo Runs (O4b)
Sposito - 6:59 Sunday 14 April 2024 (63959) Print this report
Operator Report - Night shift

Today, I found ITF in SCIENCE. 03:12 UTC ITF unlocked, I performed a CITF alignement and relocked the ITF. 06:20 UTC ITF back in SCIENCE.

No DMS event.

Images attached to this report
Virgo Runs (O4b)
berni - 23:01 Saturday 13 April 2024 (63958) Print this report
Operator Report - Afternoon shift

ITF found in Science mode.

From 18:30 UTC to 18:40 UTC ITF in Calibration to perform the planned DAILY_CALIBRATION.

At 19:35 UTC the ITF unlocked;  in the attached plot you can see a spike in the Sc_PR signals. At the same time the process ISC_Fb reported the following message:

2024-04-13-19h35m31-UTC>ERROR..-[TfbSource::StoreData] producer Sc_PR: overflow at GPS 1397072149.999912000 (received 2230 / expected 2000) (14490 times)

 

The ITF relocked at the first attempt; Science mode 20:27 UTC.

 

SBE

With the ITF unlocked I recovered the SPRB vertical position with step motors.

 

SUSP 

At the beginning of the shift, I contacted Paolo and Valerio regarding the issue with Sa_MC_F0_COIL_H1; to recover the correction, it would have been necessary to exit Science mode and perhaps unlock the ITF. We decided to continue monitoring the signal; around 16:00 UTC, the correction peaked and reversed the trend, so it was decided to postpone the intervention until tomorrow.

 

Guard tours (time in UTC)

13:00 - 13:30

17:00 - 17:30

20:00 - 20:30

21:40 - 22:10

Images attached to this report
AdV-ISC (Alignment control scheme conceptual design)
mwas - 18:35 Saturday 13 April 2024 (63957) Print this report
DIFFp set point and DARM optical gain

The DIFFp set point loop that minimizes the DIFFp dither lines in B1p DC might not give the right set point to maximize the DARM optical gain and the BNS range.

Figure 1 shows that the BNS range was decreasing by 5 Mpc yesterday for most of the day between 6:00 UTC and 19:00 UTC (afterwards there is a drop for 3h because of the calibration noise injections).

Figure 2 shows that at the same the optical gain has been decreasing, and started increasing again between 21:00 UTC and 24:00 UTC.

One can do a double demodulation of B1 at the 491.3Hz DARM line frequency and then demodulate the line magnitude at the DIFFp dither line frequency.

Figure 3 shows that at 6:00 UTC that demodulation was relatively close to zero for TX and TY, but at 16:00 UTC DIFFp TX was very far from zero. Which means that changing the DIFFp TX set point should be able to increase the DARM optical gain (and probably the BNS range)

Figure 4 shows that around 24:00 UTC when the BNS range was getting better the measured double demodulation signal was getting closer to zero.

Figure 5 shows than on April 10 when the DIFFp TX was not working and there was a forest of bumps appearing in the sensitivity the signal was even further away from zero.

So a double demodulation of B1 at 491.3Hz + DIFFp dither line frequency might be giving a good signal for the DIFFp set point to increase the DARM optical gain and the BNS range.

/users/mwas/ISC/B1_doubleDemod_DIFFp_20240331/B1_doubledemod.m

Images attached to this report
Virgo Runs (ER16)
gherardini - 15:04 Saturday 13 April 2024 (63956) Print this report
Operator Report - Morning shift

The ITF kept the science mode all the shift.

No DMS alerts in the last 8 hours.


-guard tours (UTC):
4:56 --> 5:34
6:56 --> 7:21
11:01 --> 11:28

Sub-system reports

SBE
the SPRB vertical correction is slightly increasing over its threshold, to be recover at the next unlock.

SUSP
one of MC horizontal actuator (H1) is going to saturation.

Images attached to this report
Virgo Runs (O4b)
menzione - 6:55 Saturday 13 April 2024 (63955) Print this report
Operator Report - Night shift

Upon arrival, I found ITF locked at LN3_SQZ, in CALIBRATION Mode.
At 23:04 UTC the calibration of Sensitivity concluded Science Mode set.

ITF unlocked once at 01:09 UTC (TBC). It relocked easily at the first attempt.

ITF in Science Mode for the rest of the shift.

Guard Tours (UTC) 
21:38 - 22:08
23:25 - 23:54
01:45 - 02:16
03:50 - 04:20

Images attached to this report
Virgo Runs (O4b)
Sposito - 23:00 Friday 12 April 2024 (63954) Print this report
Operator Report - Afternoon shift

Today, I found ITF in SCIENCE. 20:12 UTC I started the scheduled weekly calibration (for today, just a long DF_SENSITIVITY that will last 3 hours).

Images attached to this report
AdV-ISC (Commissioning up to first full interferometer lock)
boldrini - 22:14 Friday 12 April 2024 (63953) Print this report
Comment to PR_TX_SET investigation (63946)

I've re-checked the offset on PR_TX.

Many hours have passed, but it seems that the offset I've put on PR_TX is still good (Fig.1). Some very light skewedness can be observed on the sidebands, indicating that this offset might have become larger overtime, but I would rather not risk disturbing the lock with such a weak indication. If the lock holds, I will keep monitoring this offset over the week-end.

Images attached to this comment
AdV-DAQ (Calibration)
mours - 19:43 Friday 12 April 2024 (63952) Print this report
Comment to Hrec_hoft_20000Hz_Gated_500Hz no more available? (63949)

Indeed, the filter producing this channel was in an abnormal state. This was due to a too large change of the dynamic of the h(t) channel, due to weird h(t) values produced on April 8.

The filtering process has been restarted and the Hrec_hoft_20000Hz_Gated_500Hz channel is back.

The library version will be change during the Tuesday maintenance to use a more recent Fd version not sensitive to this kind of glitches.

AdV-COM (1/√f noise)
mwas - 19:07 Friday 12 April 2024 (63951) Print this report
Another proof that CO2 laser is not the origin of 1/f^(2/3) noise

There are noise projections and measurements done proving in a model dependent way that the CO2 DAS laser is not limiting the sensitivity (VIR-0911A-19, VIR-0199A-24).

Another proof that is model independent comes from the tuning of the TCS done in October last year starting from the TCS switched off: https://logbook.virgo-gw.eu/virgo/?r=62282 . Only the NI CO2 is a potential source of noise, as this is the one with a high power put on the CP to compensate the cold lens on the CP. The lock acquisition was done with 0.1W on the NI CP, and then two steps were performed in lock to increase the power to 0.4W.

Figure 1 shows the two steps done at 18:23 UTC and 20:28 UTC.

Figure 2 shows that there was no impact on the BNS range. If the CO2 laser was a noise source the impact on the sensitivity would be immediate and the noise level would be proportional to the CO2 laser power.

The noise fitting done a few days after that measurement had shown that the sensitivity was limited by the mystery noise at that time https://logbook.virgo-gw.eu/virgo/?r=62301. See figure 3. So if the CO2 laser was the origin of mystery noise (through RIN coupling, jitter coupling, or any other way). Then we should have seen increase in steps of the noise level in the sensitivity, which was not the case.

Images attached to this report
Detector Characterisation (Broadband noise)
fiori, tringali, paoletti - 16:59 Friday 12 April 2024 (63950) Print this report
Comment to Electric noise coupling to h(t) (63944)

The increased coherence with ENV_NEB_IPS_CURR seems associated to the accidental presence of a glitch in hrec (one of the 25-min glitches) and a glitch in the ENV_NEB_IPS_CURR sensors.

The two glitches are NOT coincident indeed but a few sec away (the IPS glitch occurs after), but they both fall in the 10s window of the Bruco computation.

Figure 1: coherences are computed 120s before the glitch (purple) and in a 120s window containing the glitches.

Figure 2: spectrograms show that the two glitches are a few seconds away. The COHETIME plot implemented in dataDisplay measures a sort of "anti-coherence" (the coherence goes to a lower value in the time window that contains both glitches).

It is not clear what is peculiar to the NEB_IPS_CURR sensor glitch to produce coherence with Hrec?

Images attached to this comment
AdV-DAQ (Calibration)
Paoletti - 16:45 Friday 12 April 2024 (63949) Print this report
Hrec_hoft_20000Hz_Gated_500Hz no more available?
Images attached to this report
Comments to this report:
mours - 19:43 Friday 12 April 2024 (63952) Print this report

Indeed, the filter producing this channel was in an abnormal state. This was due to a too large change of the dynamic of the h(t) channel, due to weird h(t) values produced on April 8.

The filtering process has been restarted and the Hrec_hoft_20000Hz_Gated_500Hz channel is back.

The library version will be change during the Tuesday maintenance to use a more recent Fd version not sensitive to this kind of glitches.

Detector Characterisation (Broadband noise)
direnzo - 16:17 Friday 12 April 2024 (63947) Print this report
Comment to Electric noise coupling to h(t) (63944)

It seems that the coherence estimation by BruCo got fooled by one of the 25-minute glitches, happening at the end of the analyzed interval, UTC 14:20:25 2024/4/11 + 900 s. The glitch is recorded by omicron at 14:33:39.68. So, the spectral estimation is biased: don't trust this result.

The coherence mis-estimation is documented in this git issue.

Figure 1: coherence spectrogram of 1 hour of data around the interval of yesterday BruCo run. The effect of the glitch is visible at 14:33 UTC as an excess of coherence. The left-hand side panel shows the estimated coherence in the 1-hour interval using the median method, which is more robust to glitches. Except for the 50 Hz line and its harmonics, no suspect coherence value is visible. Since v3r2, BruCo has available the --medianpsdestimation option to estimate the spectrum using the median instead of the average (Welch method).

Figure 2: Q-scan and whiten time series of Hrec and V1:ENV_NEB_IPS_CURR_R_2000Hz in an interval of 1 second around the time of the glitch. The current channel shows absolutely no excess noise.

But then why the coherence between the two?

Figure 3: there is in fact a glitch in V1:ENV_NEB_IPS_CURR_R_2000Hz 2 seconds after that in Hrec, and of a vaguely similar shape, as visible from the spectrograms. The similarity in the spectrum has triggered a larger coherence value in the time bin of figure 1 embracing both glitches.

To confirm that this occurred just by chance, I plotted the spectrograms for other 25-minute glitches for both Hrec and V1:ENV_NEB_IPS_CURR_R_2000Hz. For all, no glitches in the latter channel have been observed.

Figure 4: Q-scans of Hrec and V1:ENV_NEB_IPS_CURR_R_2000Hz for another glitch belonging to the 25-minute family.

Images attached to this comment
AdV-DAQ (Calibration)
vanhaevermaet - 15:52 Friday 12 April 2024 (63948) Print this report
Transfer functions between V1:Sc_*E_MIR_Z_CORR and V1:Sc_*E_MIR_VOUT_* sometimes unstable giving DMS alerts
We noticed since April 10 that during recent locks the TFMoni channels monitoring the V1:Sc_*E_MIR_Z_CORR to V1:Sc_*E_MIR_VOUT_* transfer functions around 355Hz sometimes become very unstable. The coherence drops for more than 10 minutes leading to DMS red flags and alerts. The most affected channels are those from WEMIR, in lesser extend NEMIR. BS, PR, and SR seem ok.

This was not the case during locks in the past weeks. Figure 1 shows a very stable behaviour during a lock on April 9 for WEMIR channels.
However when looking at the lock of April 10 afternoon (Figure 2) the behaviour is almost continuously bad with very low coherence, and both modules and phase showing large variations.
The situation during the locks last night (April 11-12) was stable, as with the current ongoing lock. However as we speak the channels are unstable again (see Figure 3).
The same plots can be obtained for NEMIR and show similar behaviour.

Is this expected to happen and linked to the new control scheme applied since April 10 (https://logbook.virgo-gw.eu/virgo/?r=63933) or is it triggered by a difference cause?



Images attached to this report
AdV-ISC (Commissioning up to first full interferometer lock)
boldrini - 15:31 Friday 12 April 2024 (63946) Print this report
PR_TX_SET investigation

Today I've noticed the presence of an offset on PR_TX (Fig.1). The "ball" generated by the 2-D istogram of PR_TX_INPUT and B4_12/112MHz_mag is skewed at a positive angle, suggesting that the maximum of the error signal's fluctuation should be around 0.006 mA. Both 12 and 112 MHz sidebands show agreement on this, which isn't the case for PR_TY.

Interestingly, this offset was not there a week ago (Fig.2).

I've tried to slowly change the setpoint of PR_TX to recover this offset. This was beneficial for the sidebands power, obviously, but the effect on the sensitivity is negligible (Fig.3) and it's invisible with respect to its normal fluctuation.

The offset has been introduced online, nothing in the automation has changed. Given the negligible effect on the interferometer, I see no harm in leaving it online for the rest of this lock and observe any possible difference over a longer period of time.

Images attached to this report
Comments to this report:
boldrini - 22:14 Friday 12 April 2024 (63953) Print this report

I've re-checked the offset on PR_TX.

Many hours have passed, but it seems that the offset I've put on PR_TX is still good (Fig.1). Some very light skewedness can be observed on the sidebands, indicating that this offset might have become larger overtime, but I would rather not risk disturbing the lock with such a weak indication. If the lock holds, I will keep monitoring this offset over the week-end.

Images attached to this comment
Virgo Runs (O4b)
berni - 15:00 Friday 12 April 2024 (63945) Print this report
Operator Report - Morning shift

ITF locked for all the shift.

At 8:27 UTC Diana from remote changed the TCSChiller set point to recover the standard working condition after the problem occurred yesterday evening (see entry 63940); it was decided to perform the operation without breaking Science mode.

Then, from 8:42 UTC to 8:45 UTC, Science mode was interrupted for an Adjusting break to adjust WI CO2 DAS outer ring power injected in the ITF; see plot.

 

Software

  • TCSMoni, SqzMoni, DMSserver restarted many times to take into account new configurations provided by the experts;
  • ELE_QGBT restarted after a crash at 8:26 UTC.
Images attached to this report
Detector Characterisation (Broadband noise)
mwas - 12:22 Friday 12 April 2024 (63944) Print this report
Electric noise coupling to h(t)

Looking at Bruco results from yesterday I have noticed broadband correlations that I don't remember seeing last time I looked a few weeks ago.

Figure 1. NEB IPS CURR is coherent between 20Hz and 60Hz. Did the NEB IPS CURR noise level increase in the past few weeks?

Figure 2 WI FF50Hz P ERR is coherent between 15Hz and 100Hz. I am surprised to see coherence with the 50Hz feed-forward very far from the 50Hz frequency.

It would be important to look at this in more detail. A more complete list of which channels become coherent with h(t), when did it become coherent, and if the corresponding environmental channels increase in noise level at the same time.

Images attached to this report
Comments to this report:
direnzo - 16:17 Friday 12 April 2024 (63947) Print this report

It seems that the coherence estimation by BruCo got fooled by one of the 25-minute glitches, happening at the end of the analyzed interval, UTC 14:20:25 2024/4/11 + 900 s. The glitch is recorded by omicron at 14:33:39.68. So, the spectral estimation is biased: don't trust this result.

The coherence mis-estimation is documented in this git issue.

Figure 1: coherence spectrogram of 1 hour of data around the interval of yesterday BruCo run. The effect of the glitch is visible at 14:33 UTC as an excess of coherence. The left-hand side panel shows the estimated coherence in the 1-hour interval using the median method, which is more robust to glitches. Except for the 50 Hz line and its harmonics, no suspect coherence value is visible. Since v3r2, BruCo has available the --medianpsdestimation option to estimate the spectrum using the median instead of the average (Welch method).

Figure 2: Q-scan and whiten time series of Hrec and V1:ENV_NEB_IPS_CURR_R_2000Hz in an interval of 1 second around the time of the glitch. The current channel shows absolutely no excess noise.

But then why the coherence between the two?

Figure 3: there is in fact a glitch in V1:ENV_NEB_IPS_CURR_R_2000Hz 2 seconds after that in Hrec, and of a vaguely similar shape, as visible from the spectrograms. The similarity in the spectrum has triggered a larger coherence value in the time bin of figure 1 embracing both glitches.

To confirm that this occurred just by chance, I plotted the spectrograms for other 25-minute glitches for both Hrec and V1:ENV_NEB_IPS_CURR_R_2000Hz. For all, no glitches in the latter channel have been observed.

Figure 4: Q-scans of Hrec and V1:ENV_NEB_IPS_CURR_R_2000Hz for another glitch belonging to the 25-minute family.

Images attached to this comment
fiori, tringali, paoletti - 16:59 Friday 12 April 2024 (63950) Print this report

The increased coherence with ENV_NEB_IPS_CURR seems associated to the accidental presence of a glitch in hrec (one of the 25-min glitches) and a glitch in the ENV_NEB_IPS_CURR sensors.

The two glitches are NOT coincident indeed but a few sec away (the IPS glitch occurs after), but they both fall in the 10s window of the Bruco computation.

Figure 1: coherences are computed 120s before the glitch (purple) and in a 120s window containing the glitches.

Figure 2: spectrograms show that the two glitches are a few seconds away. The COHETIME plot implemented in dataDisplay measures a sort of "anti-coherence" (the coherence goes to a lower value in the time window that contains both glitches).

It is not clear what is peculiar to the NEB_IPS_CURR sensor glitch to produce coherence with Hrec?

Images attached to this comment
AdV-SBE (EIB-SAS commissioning)
bulten - 11:56 Friday 12 April 2024 (63942) Print this report
Comment to EIB ground noise correction, and backscattered light towards SIB1 (63763)
This previous report was not reported at the date I wrote it, I found it in my drafts. Sorry for that.

I compared the EIB SAS movement in z (south) direction with the Sa_IB_F0_x (north) direction on April 2, 13:00 UTC with Jan 18, 13:30 UTC;
both days had high wind speed in PISA and extra microseismic activity. In the plots, EIB_ground_z is derived from the geophone on the
ground below the EIB bench. It is this geophone on which a different filter is applied, to match better Sa_IB_F0_x, which id the LVDT
signal from the injection bench superattenuator. So assuming that between 0.1 and 2 Hz the F0_x should be opposite to ground_z, you expect
a transfer function of 1. Before March 27, when the new calibration was applied, we had a large phase difference in the filtered geophone response
and the superattenuator around 0.3 Hz, where the maximum of the microseismic noise appears. After March 27 this phase difference is smaller, albeit
below 100 mHz I now have less reduction of the geophone DC drift (cutting off the part below 100 mHz gave too large phase shifts and too large
reduction in the range 100mHz- 1 Hz).

EIB_LVDT_z is the LVDT reading of the EIB; it should be minus SA_F0_x (since the EIB z-axis points towards the -x direction in IB). Thus optimally,
the transfer function EIB_LVDT_z/Sa_IB_x should be 1 with a phase of -pi. Same for EIB_ground_z/Sa_IB_F0_x. The EIB_LVDT_zb channel is the sum
of EIB_LVDT_z and EIB_ground_z; this is the channel that we try to control to 0 in the closing of the loop. Thus this channel gives an indication of the
residual motion.

As can be seen in plots of Jan 18 and April 2, the LVDTs for EIB_z and Sa_IB_x broadly overlap, but the EIB has extra motion that peaks around 0.8 Hz.
This is about a factor of 5 above the natural resonance of the IP legs of EIB and close to the Ty resonance; this extra motion is due to un-optimal
control in the PID loops, maybe also due to blending the geophones on the springbox with the LVDT. At 0.8 Hz, the EIB motion of the bench is
basically equal to the motion of the ground (EIB_LVDT_z ~ 2*Sa_IB_F0_x and EIB_LVDT_zb, EIB_ground_z ~ 1* SA_IB_F0_x).
You can also see that the ground noise before march 28 was underestimated by about 20% around 0.5 Hz and that the phase difference reaches 90 deg. around 0.2 Hz.
After modifying the filter for EIB_ground_z (which is in the control loop, so it also modifies the bench response in closed loop), on April 2, we see that the
ground motion compared much better with the IB motion; the amplitude of the transfer function is about 1.05 and the phase is much flatter; also the transfer function between EIB_LVDT_z and Sa_IB_F0_z improved. Now the maximal deviation around 0.8 Hz reached about 1.5; giving twice better subtraction of
ground noise. You can also see that EIB_LVDT_zbench is smaller; this is our best measurement of the residual motion of the EIB bench.

In the third figure, I plotted the results for the first 2 figures on top of each other (the reference plot is the April 2 data and the blue line the Jan 18 data)
to compare the change in transfer functions. You can see that the 30 minutes of data of Jan 18 contained a bit more seismic noise than on April 2.
Nevertheless, also the April-2 data contains so much excess microseismic noise that the quality of subtraction can be judged; at april 2 we do better than
at Jan 18. Further improvements could be made, if required, by changing the PID loops, but the EIB is a highly coupled system with tilt stabilization; z and Tx,
x and Tz, and indirectly Tx,Tz and Ty are strongly coupled. It is a priori not clear that we can improve much in the loops and it requires careful study of the
blending of the geophones on the spring box, the loop gains for the vertical and horizontal d.o.f.s etc.



Images attached to this comment
AdV-TCS (CO2 laser projector)
lumaca, nardecchia, berni - 11:20 Friday 12 April 2024 (63943) Print this report
WI CO2 chiller setpoint change

Following the activity of yesterday night (63940), we noticed that the WI main CO2 laser continued to be in an unstable state, so we decided to act on WI CO2 chiller setpoint, changing it from 19.02 °C to 19.04°C (08.27 UTC, Fig. 1). Also the BCK chiller set point has been changed at the same setpoint.

Soon after, we noticed a prominent change in the WI CO2 signals and we needed to recover the WI CO2 DAS outer ring power injected in the ITF, by rotating back the relative wave plate to recover the condition with respect to yesterday’s action (08.45 UTC, Fig. 2).

We’ll continue to monitor the situation to evaluate if a further chiller setpoint small change will be needed.

Images attached to this report
AdV-SBE (EIB-SAS commissioning)
bulten - 11:08 Friday 12 April 2024 (63763) Print this report
EIB ground noise correction, and backscattered light towards SIB1
During the afternoon shift we had time to commission EIB better. This is a follow-up on entry 63491, backscattered light noise hunting.
Originally, I wanted to track SIB1 just like SNEB, SWEB, SPRB and SDB2 are tracking the superattenuators, but unfortunately SIB1
operates at a setpoint in x of 991 micrometer, and I cannot blend that easily with the LVDTs of EIB.
EIB measures he ground displacement via geophones on the floor below the EIB bench. The phase between the geophone signal and the IB filter0 LVDTs
had a slope and the filtered ground signal for EIB was a bit too small. Therefore, I applied a filter that corrected the phase shift, and another high-pass filter,
to get a better match between the ground noise and the LVDT readings in SIB1.
Figure 1 gives the transfer function between ground-z and Sa_F0_X and also between ground_x and SA_F0_Z.
The reference plot is with the old filter, the blue line with the new filter, which is the old filter times (s(s+1))/(s^2+0.7s+0.08).
Clearly, the phase and the gain are much better. For ground_x, the gain of the subtraction has a slope and we under-subtract ground noise at 1 Hz, but
ground_z is the relevant correction, since that is the distance between EIB and the input mode cleaner (the south direction).
There is some further room for improvement but that requires a new time to try out the filter.

Furthermore, the geophones on the bench seemed completely mis-calibrated. I tried to get a better calibration by injecting Ty noise and changing the filters
a bit. The problem with the geophones on the bench is that at low frequency, the signal is coming from the tilt Tx,Tz of the bench, not from the acceleration.
Therefore it was difficult to do a good calibration. We should do the transfer function between the geophones on the bench and the ground with the bench
blocked, but that requires another 2 shifts (one to measure and implement it with blocked bench and another with floating bench and noise injection, to
see if everything is still OK in the presence of Tx and Tz tilts) so for the moment I think we should leave that.
I did a rough job getting a better calibration with the injected Ty but it is in no way perfect; the bench positions below 1Hz come from the LVDTs and the ground noise and they can be trusted. Above 1Hz, the spring box is used in the controls and the bench geophones are tilt-corrected and used as monitor signal in EIB_x,EIB_ty, EIB_z. Above 1 Hz, these signals are not accurate (but should be better than with the previous geophone filters) but they are not used in
the PID control, so I think that that is OK.







Images attached to this report
Comments to this report:
bulten - 11:56 Friday 12 April 2024 (63942) Print this report
This previous report was not reported at the date I wrote it, I found it in my drafts. Sorry for that.

I compared the EIB SAS movement in z (south) direction with the Sa_IB_F0_x (north) direction on April 2, 13:00 UTC with Jan 18, 13:30 UTC;
both days had high wind speed in PISA and extra microseismic activity. In the plots, EIB_ground_z is derived from the geophone on the
ground below the EIB bench. It is this geophone on which a different filter is applied, to match better Sa_IB_F0_x, which id the LVDT
signal from the injection bench superattenuator. So assuming that between 0.1 and 2 Hz the F0_x should be opposite to ground_z, you expect
a transfer function of 1. Before March 27, when the new calibration was applied, we had a large phase difference in the filtered geophone response
and the superattenuator around 0.3 Hz, where the maximum of the microseismic noise appears. After March 27 this phase difference is smaller, albeit
below 100 mHz I now have less reduction of the geophone DC drift (cutting off the part below 100 mHz gave too large phase shifts and too large
reduction in the range 100mHz- 1 Hz).

EIB_LVDT_z is the LVDT reading of the EIB; it should be minus SA_F0_x (since the EIB z-axis points towards the -x direction in IB). Thus optimally,
the transfer function EIB_LVDT_z/Sa_IB_x should be 1 with a phase of -pi. Same for EIB_ground_z/Sa_IB_F0_x. The EIB_LVDT_zb channel is the sum
of EIB_LVDT_z and EIB_ground_z; this is the channel that we try to control to 0 in the closing of the loop. Thus this channel gives an indication of the
residual motion.

As can be seen in plots of Jan 18 and April 2, the LVDTs for EIB_z and Sa_IB_x broadly overlap, but the EIB has extra motion that peaks around 0.8 Hz.
This is about a factor of 5 above the natural resonance of the IP legs of EIB and close to the Ty resonance; this extra motion is due to un-optimal
control in the PID loops, maybe also due to blending the geophones on the springbox with the LVDT. At 0.8 Hz, the EIB motion of the bench is
basically equal to the motion of the ground (EIB_LVDT_z ~ 2*Sa_IB_F0_x and EIB_LVDT_zb, EIB_ground_z ~ 1* SA_IB_F0_x).
You can also see that the ground noise before march 28 was underestimated by about 20% around 0.5 Hz and that the phase difference reaches 90 deg. around 0.2 Hz.
After modifying the filter for EIB_ground_z (which is in the control loop, so it also modifies the bench response in closed loop), on April 2, we see that the
ground motion compared much better with the IB motion; the amplitude of the transfer function is about 1.05 and the phase is much flatter; also the transfer function between EIB_LVDT_z and Sa_IB_F0_z improved. Now the maximal deviation around 0.8 Hz reached about 1.5; giving twice better subtraction of
ground noise. You can also see that EIB_LVDT_zbench is smaller; this is our best measurement of the residual motion of the EIB bench.

In the third figure, I plotted the results for the first 2 figures on top of each other (the reference plot is the April 2 data and the blue line the Jan 18 data)
to compare the change in transfer functions. You can see that the 30 minutes of data of Jan 18 contained a bit more seismic noise than on April 2.
Nevertheless, also the April-2 data contains so much excess microseismic noise that the quality of subtraction can be judged; at april 2 we do better than
at Jan 18. Further improvements could be made, if required, by changing the PID loops, but the EIB is a highly coupled system with tilt stabilization; z and Tx,
x and Tz, and indirectly Tx,Tz and Ty are strongly coupled. It is a priori not clear that we can improve much in the loops and it requires careful study of the
blending of the geophones on the spring box, the loop gains for the vertical and horizontal d.o.f.s etc.



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On-call intervention (General)
boldrini, lumaca, menzione - 10:20 Friday 12 April 2024 (63939) Print this report
ISC oncall intervention

I've noticed that the ITF unlocks some 20 minutes after reaching LOW_NOISE_3_SQZ, due to a 5 Hz oscillation visible mostly on PR_TX (Fig.1).

I have decreased PR_TX gain from 3.3 to 2.2 in CARM_NULL_1F, this gain is not changed for the rest of the lock acquisition. This does not seem to affect the lock acquisition in any undesirable way.

This change in gain might be motivated by a slow increase in sidebands power (Fig.2), after the drift in the WI DAS power (63940) around 19:00:00 UTC.

 

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Virgo Runs (O4b)
ruggi - 9:39 Friday 12 April 2024 (63941) Print this report
Comment to Operator Report - Night shift (63938)

The lock acquisition failures in fact happened around the transition to LN1, but the transition itself was fine, with no 1.8 Hz oscillation or other evident issue. The spikes visible in the corrections are normal: they are due to NI/WI relays switch.

he third unlock occurred before the transition.

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Virgo Runs (O4b)
menzione - 6:56 Friday 12 April 2024 (63938) Print this report
Operator Report - Night shift

Upon arrival I found ITF relocking. The B1p spot was miscentered respect to the camera, so I moved with the fixed setpoint up to CARM_MC_IR, then I engaged again the floating setpoint.
ITF reached LN3_SQZ but at 22:00 UTC we discovered a problem with TCS_WI_CO2_PWROUT. I contacted TCS expert who fixed the problem (ADJUSTING MODE set).
After a couple of locking attempts ITF locked again in a stable way.
SCIENCE_MODE set at 23:37 UTC.
ITF unlocked 3 times during ACQUIRE_LN1 (TBC) so I decided to wait a bit in DC_READOUT. LN3_SQZ acheived at 04:30 UTC.
SCIENCE_MODE set at 04:31 UTC.

Guard Tours (UTC time)
21:06 - 21:35
23:01 - 23:29
01:02 - 01:31
03:02 - 03:31

Sub-system reports

DAQ
NewtonNoise
02"15 UTC - NNC_CEB_LEV2 process crashed. I tried to restart it via VPM without success:
Log: 
FATAL..-Device V1:NN_CEB_INF_Z_209> No response after IP configuration
WARNING-Device V1:NN_CEB_ACC_Z_226> Writing invalid data with comment INFO_ZEROS, INFO_DATA_INVALID, INNO_DATA_TOO_SHORT, INNO_DATA_LENGTH, SERVICE_TIME_INTERVAL_HIGH, SERVICE_TIME_INTERVAL_SKIPPED, SERVICE_DATA_NO_REQ_LAST_SEC, SERVICE_DATA_OVERWRITTEN, 
WARNING-Device V1:NN_CEB_ACC_Z_217> Writing valid data with comment SERVICE_TIME_INTERVAL_HIGH, SERVICE_TIME_INTERVAL_SKIPPED, SERVICE_DATA_NO_REQ_LAST_SEC, SERVICE_DATA_OVERWRITTEN, 

Oncall events

TCS
(11-04-2024 21:55 - 11-04-2024 22:20) From remote
Status: Ended
Description: Power_DAS_OUT_is_out_of_range
TCS_WI_CO2_PWROUT at 3.6

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Comments to this report:
ruggi - 9:39 Friday 12 April 2024 (63941) Print this report

The lock acquisition failures in fact happened around the transition to LN1, but the transition itself was fine, with no 1.8 Hz oscillation or other evident issue. The spikes visible in the corrections are normal: they are due to NI/WI relays switch.

he third unlock occurred before the transition.

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