Reports of 46933
AdV-ISC (Commissioning up to first full interferometer lock)
maggiore, ruggi, valentini - 0:21 Friday 14 May 2021 (51782) Print this report
LSC shift report: CARM offset characterisation

The aim of the shift was to characterize the interferometer when locked only on the IR laser (Both the CITF and the ARMS), with a CARM offset of 300 Hz.  Additionally, a new filter for CARM and DARM when locked on the IR was developed and implemented.

The shift started with locking the arm cavities on the ALS and adding an offset of -3000 kHz. We proceeded then in prealigning the CITF and locking the DRMI. After some tuning of the gains, the DRMI was locked at 15.05 UTC and a first attempt of carm offset reduction was performed, reaching -300 Hz of offset at 15.13 UTC. The PRCL gain was lowered from 0.15 to 0.8 to mantain the system stable at values lower 

We then attempted at 15.32 UTC a hand-off of DARM from the green beating signal to LSC_B7_B8_DC_DIF_NORM but the arms immediately unlocked. The issue was caused by an error in the setting of the setpoint during the handoff.

We proceeded relocking the arms on the ALS system and the DRMI at 17.20 UTC.  THis attempt of relocking the DRMI took more than one hour and required a significative reduction of the MICH gain from 1.5 to 0.7 to be performed.  Again, the offset was reduced to -300 Hz at 18.21 UTC with the usual reduction of the PRCL gain (0.08).

We proceeded with a successfull handoff of CARM and DARM at ~18.45 UTC after re-measuring the relative gains between the IR and the Green laser signals. The transfer functions can be seen in figure 1.  The results were different from the values measured previously. In particular the gain had opposite sign due to the usage of a negative CARM offset instead of a positive one. The relative gains used for this configuration were:

  • DARM: 2440
  • CARM: 1400

The functions in carm_darm_green_m have been updated to allow for a handoff  IR with different gains and to compute automatically the setpoint for the given gain. More details on the changes in the locking scritps will be added in a separate entry.

 

We then proceeded performing LSC noise injections on all the DOFs. The injections were performed with the DRMI locked, CARM and DARM locked on the IR B7 and B8 signals with 300 Hz of Carm Offset, according to the following table:

UTC duration (s) DOF Amplitude Noise FIlter
19.20 300 DARM 2e+4 DARM_noise

19.34

300 CARM 5e+4 DARM_noise
19.46 240 PRCL 2e+3 PRCL_noise
19.52 300 MICH 2e+2 MICH_noise
20.03 300 SRCL 2e+2 MICH_noise

During the noise injection, the 150 Hz resonance was clearly noticeable both on CARM and DARM error signals.

We then attempted a further reduction of the CARM offset at 20.10 UTC but an error in setting the setpoints caused an unlock.

In the meantime, a new filter for CARM and DARM has been designed and added in LSC_Acl with the name ALS_Arm_control_IR2. The function carm_darm_ir_filter should enable this filter but has not been tested yet.

Several attempts at relocking the DRMI were then performed (after relocking the arms on ALS) but were unsuccessfull.

We then left the ALS system nodes in DOWN and the arm cavities locked on the IR lasers.

 

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Detector Operation (Operations Report)
gherardini - 23:01 Thursday 13 May 2021 (51781) Print this report
Operator Report - Afternoon shift

The scheduled ISC activity was carried out by Michele, Paolo and Riccardo without any major problem and it is still in progress...

SUSP
From yesterday evening at 22:29UTC we lost the data from Sa_SR DSP (see plot), I tried to stop/restart the SUSP_Fb sever without success (DAQ and SAT experts informed); according to Valerio to restore the data collection he needs to open/close the SR controls, so to not interfere with the ISC activity of this afternoon we decide to postpone the intervention to tomorrow morning.

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Payload (Payload)
Perciballi Naticchioni and Majorana - 17:47 Thursday 13 May 2021 (51779) Print this report
LM for O5

Large Mass Marionette and actuation cage assembling at 1500 West Clean Room Lab. Thanks Maurizio and Luca !

The marionette (180 kg) is floating inside the cage. Pitch and roll Frequency as expected. 

Notice the hole at the center of the assembling bench. It serves for the precision movement jack meant to lift-up the mirror, once the box hosting it will be open and correctly be placed. 

This is only an overall test of the structure.  

Struggling with the upload of movies .. I FORGOT TO MENTION THE ESSENTIAL CONTRIBUTE OF THE EGO PERSONNEL 

WE ARE INDEBTED with Alessio, Fabio, Fabrizio, Marco, Nicola and Michele 

Works in whashng faciity, clean rooms and mechanical workshop have been provided promptly and accurately (indeed, as usual)

 

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Non-image files attached to this report
AdV-PSL (Laser Bench setup)
derossi, melo, spinicelli, chiummo - 17:00 Thursday 13 May 2021 (51758) Print this report
Comment to swap ML (51750)

The so called ML spare, which has been swapped and is now running is the Mephisto 1000NE SN: 1222

The procedure we followed (previously discussed with M. Turconi and W. Chaibi) is reported below:

  • IMC unlocked
  • ML thermal and PZT corrections disconnected. The ML current is 2A and the crystal temperature 22.75 C
  • Measurement of the ML PZT loop TF. The purpose was to measure the TF of the ML piezo to an excitation and compare is with the spare ML, in order to verify that the two responses are similar. First of all we checked the control bandwidth of the PMC piezo loop by injecting sinusoidal lines of 1.6Vpp amplitude directly on the PZT input of the ML and looked on the Pre mode cleaner piezo corrections PSL_PMC_PZT and found a cutoff frequency of 1400 Hz (1st plot).
GPS (Local Time) Freq [Hz] Amplitude [Vpp] Comments
09:57:20 102 1.66 V  
09:59:20 211 -  
10:01:00 501 - -
10:04:30 901 - -
10:10:50 1990 - the piezo doesn't follow, out of the band
10:13:50 1320 -  
  • We injected noise on the ML PZT with the fast DAC. The filter used for the noise is the one in Acl called SSFS noise IMC which has a zero at 100 Hz and a pole at 1000 Hz (2nd plot). However we didn't manage to exploit data since we found out we had no coherence between the PSL_PMC_REFL_I and the noise (plot 3). Next time we should increase the amplitude of the applied noise if we want to measure the TF in this way.
  • Measurement of the ML TH loop TF. We injected noise with a fast DAC. The filter has a zero at 1Hz, a pole at 5 Hz at another pole at 40 Hz (4th plot), and measured the TF (5th plot).
  • We switched off the fiber amplifier and measured the power in transmission of the ML fiber on the LB and of the pickoff for the fiber amplifier seeder (470 mW and 132 mW)
  • We injected the spare ML into the fiber going the LB. We set it at 2.074 A and the crystal temperature at 24.73 C. However, we didn't recover the same coupling 51579. However, since the fiber amplifier works in saturation, it was enough to switch it on again and also lock the SL.
  • Measurement of the ML PZT loop TF, with the same filter of fig. 2 (plot 6).
  • Measurement of the spare ML TH loop. We found a similar response (plot 7, in blue is the spare ML, in pink the previous measurement).
  • While doing this operation we misaligned the collimator of the ML previously installed. We struggled to reinject it and we didn't manage to recover the same output power. We have now around 130 mW in transmission of the fiber and we should optimize this coupling soon.
  • We measured the IMC TF function and adjusted the gain. We passed from 4 to 6 dB attenuation and recovered a UGF of 140 kHz (plot 8).

We let the system locked with the spare ML and until now we did't observe any strange behaviour of the noise eater (as it was the case for the old ML).

However, we should check and maybe tune the crystal temperature because we are probably next to a mode hop. The instability observed yesterday (51771) is probably due to a bimodal behaviour of the ML (9th plot).

 

 

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AdV-ISC (Commissioning up to first full interferometer lock)
boldrini, casanueva, mantovani, ruggi - 16:53 Thursday 13 May 2021 (51777) Print this report
ISC shift: CARM offset reduction

Goal of the shift was to further reduce the CARM offset, after implementing the filter devised for this task.

We began the shift by measuring, as asked by OptChar, the FSR of the cavities. We first reduced the CARM offset with a 5 minutes long ramp, starting 2000 Hz on one side of the IR peak (UTC 7:35:00), and went more than 110 kHz in the opposite direction to scan two resonances. We then went back in 30 seconds (Fig.1).

We proceeded by locking CARM and DARM on the green lasers and then the CITF. The hand-off was performed smoothly multiple times, but we never managed to get closer to the IR resonance than 200 Hz.

We tried to implement the new filters, identical to the previous CARM and DARM filters with a different roll-off. In particular, introducing the new controller on DARM reinjected high frequency noise and provoked un unlock. A better filter is already under developement and will be tested in the next shifts. The structure at 150 Hz, that causes the noise seen on B7 and B8, is expected from simulations. It is also expected to move to lower frequencies by reducing the CARM offset, down to 10 Hz when we get very close to resonance. The target is to characterize the TF to evaluate whether we can reduce the offset until we can jump to the resonance, or try to compensate it with a filter.

Even if we could not reduce the CARM offset further than we already did in the past, we managed to perform the hand off smoothly and, assuming no issues arise in locking the arms and the CITF, the whole procedure can be completed in under 5 minutes. This makes it possible to elaborate a better strategy, for example by injecting noise on the DoFs in this configuration.

A few interesting observation about our repeated attempts today:

  • PRCL gain is set to 0.15 in the Metatron node. This value allows the CITF to lock, but it is too high to keep it that way. The CITF performed better after reducing it to 0.12 immediately after locking, and then again to 0.08 when reaching CARM offset = 500 Hz
  • MICH gain is set to 1.5 in the Metatron node. This value allows the CITF to lock, but it is too low to keep it that way. The CITF performed better after increasing it to 2.0 immediately after locking. No further adjustement was needed for MICH, today.
  • While the alignment of the PR seemed to be critical, as always, for locking the CITF, we managed to achieve a lock with the BS grossly misaligned multiple times, and the lock was robust enough to adjust the BS's position with the local control without breaking it.
  • About the BS, we considered closing its drift control again, but we noticed  that the B1p_6MHz quadrants did not behave well enough to be implemented ad the present moment. Further study pending. We left the BS angular control open, as the priority was give to the hand off to the IR signals for CARM and DARM.

We leave the ITF with the arms locked on the IR and everything else in DOWN, recycling mirror MISALIGNED.

 

 

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Detector Operation (Operations Report)
menzione - 15:41 Thursday 13 May 2021 (51775) Print this report
Operator Report - Morning shift

06:10 UTC - after the tuning in the safe position of SDB1, I easily locked both cavities on infrared.
The planned Commissioning activity on "ISC - CARM offset (carried out by Boldrini, Casanueva) started at 06:30 UTC and went on without major problem for the whole shift.

Parallel activities:
SQZ - activity in Det Lab

DAQ
09:00 UTC - FbTrend_10800 process crashed, killed via shell, restarted via VPM.

AdV-ALS (Green sources)
derossi, spinicelli, chiummo, melo - 12:33 Thursday 13 May 2021 (51776) Print this report
West beam green alignment

Yesterday, ISC team asked us to align the green source coming from the West Arm as they couldn't see flashes to lock the cavity. So, we went to Laser Lab to perform this operation.

We first opened all loops, put the PMC in scan then blocked the beam in the output of the LB. Then, we blocked EIB, released again the beam in the output of LB, and locked the PMC. In order to lock the arms with the green laser, RFC has to be locked. To lock the loops again, we needed to correct position of SIB1 mainly in TZ to let the automatic alignment working and restore the power of INJ_IMC_TRA_DC. At this point, we could lock the Mode Cleaner in drift control and the RFC.

Then, we aligned the green beam coming from the west arm on the photodiode, looking at the signal ALS_WARM_CEB_BEAT_DC. Since the photodiode was quite misaligned, we only had small flashes. We then improved the alignement and, when the flashes were high enough, ISC team locked the green (plot 1) and we left the alignment in that position.

To put the system again in operation, we opened again the loops, put the PMC in scan, blocked the beam in the output of LB and resuspended the EIB bench, since the position of the bench remained almost the same. Then, we released the beam in the output of EIB, locked the PMC and realigned the Mode Cleaner putting it back in the original position (touching the controls of SIB1). Finally, we locked again all the loops, and left the laser lab.

However, ISC team reported that the flashes of the green coming from the West had disapperead again. We realized that probably when we realigned the position of SIB1 for restoring the full power of IMC_TRA, we lost the alignment of the green (plot 2). So, we went back to laser lab, opened the loops and blocked the bench again. However, instead of aligning the Mode Clenear, this time we changed the set points of the BPC and aligned the green beam from West (plot 3). FInally, we put everything back in place (resuspended EIB, closed all loops, etc..)

We left the laser lab around 18h local time.

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Detector Operation (Operations Report)
menzione - 8:21 Thursday 13 May 2021 (51774) Print this report
Operator Report - initial shift

ITF State: Cavities unlocked.
ITF Mode: Not Locked.
Quick Summary: IMC and RFC locked (IB AA still disabled); all Suspensions loops closed; all SBEs loops closed. SDB2 Stepping Motors still on, tracking loop Open.
Activities ongoing since this morning: No activity is known so far in the control room. 

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AdV-ISC (Commissioning up to first full interferometer lock)
bersanetti, maggiore, amagazzu - 1:26 Thursday 13 May 2021 (51771) Print this report
ISC shift: CARM/DARM handoff to B7/B8

The goal of the shift was to study the handoff of CARM/DARM from the beating signals to the B7/B8 DC recombinations while still having around 300 Hz of CARM offset.

After the work in the Laser Lab ended, there was the need to restart the green at NEB, and then another realignment of the ALS WARM in CEB was needed. After that we could recover the lock acquisition (a tuning of the lock thresholds for both North and West ALS was needed) and we could start the activity, around 16:00 UTC:

  • We relocked the arms in the CARM/DARM basis on the beating signals on resonance for the IR at 16:20 UTC; one minute later, a + 3 kHz offset was added to CARM;
  • at this moment we had some short instability of the INJ system, with a couple of unlocks and the MC transmitted power going down for a short time; the system then recovered itself;
  • we went back to the same configuration again at 16:37 UTC (when we unlocked) and then at 16:47 UTC;
  • we started to work on the DRMI which, after a first pre-alignment of both the SR and PR mirrors, could lock rather easily and in a reproducible way for the entire shift, without any change in loop parameter, up to the 3f handoff of both the LSC and ASC loops; after a short unsuccessfull test, the BS drift control was left open for the rest of the shift;
  • once starting to reduce the CARM offset, the only change of gain which was needed was for PRCL, from 0.15 to 0.06; MICH could benefit from a higher gain (UGF ~ 12 Hz) but doing so increased the unlocks due to saturations, so it was tested only twice and the loop was kept with such UGF in following trials;
  • for the most part of the shift, we could reliably move from 3 kHz CARM offset to 300 Hz in a single 10 s long ramp, while decreasing the PRCL gain and blocking the B1p and B4 triggers at the same time;
  • then we started to study the handoff of CARM and DARM to respectively LSC_B7_B8_DC_SUM_SQRT and LSC_B7_B8_DC_DIF_NORM; while doing this we suffered from an unlock at around 18:24 UTC; the cause is not clear, but we observed the NI_F7 and NI_PAY flags on the DMS becoming grey just after this event;
  • we continued this study, and we made the handoff of DARM at 19:10:10 UTC, using the DARM UGF line and recent measurements for the sensing and offset changes; we unlocked while doing the same for CARM;
  • we made another handoff of DARM at 19:47:50 UTC, and we unlocked shortly after, maybe because of the big 150 Hz noise present on the B7/B8 reconstructed signals; there is the already seen noise bump in the 100-200 Hz region, but the highest noise was at 150 Hz sharp;
  • at around 20:18:50 UTC we did another handoff, this time of CARM; then at 20:23:05 UTC we also made the DARM one, immediately reducing the line amplitude to decrease the noise; again, we unlocked shortly after; about this handoff:
    • Figure 1 shows the timeline;
    • Figure 2 shows the spectra of the Err/Corr signals when both CARM/DARM where on the beating signals (purple traces) and on the B7/B8 reconstructed signals (blue traces); the 87.1 Hz line in DARM is the UGF line we injected;
    • Figure 3 shows the DARM spectrum in four different cases: BLACK: DARM on beating signal, CARM on beating signal; PURPLE: DARM on B7/B8, CARM on beating signal (bump and 150 Hz noise as described above); GREEN: DARM on beating signal, CARM already on B7/B8; BLUE: DARM on B7/B8, CARM already on B7/B8;
    • in all the trials, the DARM UGF remained constant, around 14-15 Hz;
    • the parameters for the change of calibration and offset could vary by a 10-20% for each different trial, which could be related to the uncertainty we have on the determination of the IR resonance with the beating signals; it could be worth to check and calibrate those reconstructed signals while still locked on the IR, in a similar way to what we do with the beating signals themselves; this would require putting some offsets on the single arms lock in order to move away a bit from the IR resonance, so we need to check if it is feasible at all.

During the latest part of the shift the INJ system started again to have troubles, with frequent, slow dips on the PMC power, followed by some PSTAB instability; then the system recovered just as slowly, or immediately in case the IMC unlocked.

While doing this I noticed the ALS reflected powers (ALS_*EB_PD_REFL_LP) being quite higher than usual and following a strange trend. In Figure 4 there is such trend: the first jumps on the BEAT_DC signals are due to the lock/unlock of the ALS, but the trend is visible. The trend of the PMC power is opposite to the one of the ALS_CEB_PD_GREEN_MONI signal (zoom in Figure 5).

In agreement with the INJ crew, we left all the locking nodes in DOWN, and also INJ_MAIN in DOWN and paused.

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AdV-SVS (Pre-commissioning)
sorrentino, mehmet, vahlbruch - 0:47 Thursday 13 May 2021 (51773) Print this report
Squeezing measurement on EQB1

After the tuning of AEI squeezer, a test of squeezing level  was done on the external homodyne detector with the squeezed beam folded on the EQB1 delay line. With the CC beam prealigned on the LO beam with the AA servo, and with CC loop engaged at moderate gain (=1000, DSP filter 0), the measured anti-squeezing was about 5 dB and squeezing was slightlyu more than 2 dB. In Fig 1 the blue spectra are without squeezing, yellow with anti-squeezing, magenta with squeezing. The visibility of BAB-LO contrast was previouly measured to be about 92%.

After the accidental misalignment of the squeezed beam, it was not possible to reliably engage the automatic alignment, and we could not repeat the measurement with a better tuning of the CC loop. The squeezer was switched back to BAB mode today around 16:20 UTC.

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AdV-FLT (Pre-commissioning)
bertolini - 0:20 Thursday 13 May 2021 (51772) Print this report
Comment to FCIM DDS module problem (51769)

After the replacement of the DDS with the function generator, i have re-calibrated the LVDTs by injecting white noise between 0.05-0.2Hz in Z and measuring the transfer function between LVDT-Z and Trillium-Z. Then i have centered the IP using the step motors and close the position loops for the night. In FCIM the new guardian is already implemented.

AdV-SVS (Pre-commissioning)
sorrentino, garaventa - 0:20 Thursday 13 May 2021 (51768) Print this report
HD misaligned

Yesterday morning the 4 MHz beat note between LO and CC at the homodyne detector was suddenly lost at 7:38 UTC, see first picture. Since the DC readout of the HD photodiode did not change, this was likely due to a misalignment of the squeezing beam reaching the homodyne detector: at the same time the green beam was sent from EQB1 to SQB1 by flipping a movable retro-reflection mirror quite close to the delay line on the IR optical path. The misalignment is probably due to a mechanical contact between the flip mirror and the translation stage of the delay line.

To recover the alignment we observed the subcarrier beam, which was previously well aligned on the OPA, on the HD cameras. We had to move the DL_M4 mirror horizontally by 24000 picomotor counts to bring the beam within the range of the automatic alignment on the LO beam, see second picture.

Images attached to this report
Detector Operation (Operations Report)
amagazzu - 0:04 Thursday 13 May 2021 (51770) Print this report
Operator Report - Afternoon shift

The first part of the shift was dedicated to the conclusion of the ISYS activity in Laser Lab. The INJ system was back online from 14:45 UTC, but further tunings were required in Laser Lab to restore the ALS Green beam.
From 16:00 UTC the planned ISC activity, CARM offset, carried out by Bersanetti and Maggiore, started.
From 19:21 to 19:37 UTC the Commissioning Crew noticed that the Input Mode cleaner power was fluctuating ( see attached plot #1 ), it returned to its nominal behavior soon after.
The ISC activity was concluded at 21:00 UTC, but the IMC power started to fluctuate again, going down to the power of 17.5 W ( see attached plot #2 ). I contacted the INJ Oncall (Spinicelli) and in agreement with him, I left INJ_MAIN in Pause and the Mode Cleaner in Drift Control.

Other activities carried out during the shift

  • SQZ work in DET Lab (SQZ Team);
  • Work from remote on FCIM_SBE (Bertolini).

Air Conditioning
At 14:50 UTC I switched the UTA INJ back to "Portata Ridotta".

DAQ
- EnvMoni restarted at 14:36 UTC to update mean(ENV..ESQB1_HU,30) flag thresholds.
- From 15:55 UTC to 16:55 UTC TCSMoni was restarted multiple times under request of Nardecchia to update the related TCS flags.

DET
At 15:00 UTC I verified SDB1 Safe position. The values were still correct since this morning, no further tuning required.

ISYS
(12-05-2021 21:20 - 12-05-2021 21:50) From remote
Status: Ended
Description: The Output Power of the Input Mode Cleaner started heavily fluctuating.
Actions undertaken: Spinicelli investigated from remote the issue, as a safety precaution INJ_MAIN was left in pause and he put the IMC in Drift control for the Night.

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AdV-FLT (Pre-commissioning)
bertolini, capocasa, guo - 22:27 Wednesday 12 May 2021 (51769) Print this report
FCIM DDS module problem

Last week, we changed the power supply for the FCIM crate to an independent power supply (see entry 51645)

It didn’t help to solve the jump issue and we found that the coil current monitor channels  became very noisy for marionette vertical coils and mirror coils (pic1). This situation never appeared in the past. So we changed the power supply back to it original one, and the excess of noise disappeared.  

Then we tried to recover the system, starting from the control of the bench but we found that the DDS board was not working anymore. To confirm the problem is the DDS board and not the crate, we plugged the FCIM DDS module to the SQB2 crate, there was still no output signals. So at this moment we are providing the 10kHz signal for LVDT with an external signal generator. (Pic2) Under this condition, we checked again the coil current monitor signals, the jumps still exist (pic3).  We are still suspecting that the electric problems are coming from the crate. A spare crate has been sent from Nikhef this Monday, we expect it to arrive before Friday.

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Comments to this report:
bertolini - 0:20 Thursday 13 May 2021 (51772) Print this report

After the replacement of the DDS with the function generator, i have re-calibrated the LVDTs by injecting white noise between 0.05-0.2Hz in Z and measuring the transfer function between LVDT-Z and Trillium-Z. Then i have centered the IP using the step motors and close the position loops for the night. In FCIM the new guardian is already implemented.

AdV-SIN (Installation)
capocasa, polini, vardaro - 19:15 Wednesday 12 May 2021 (51759) Print this report
Test PSDs from ICCUB
We checked with the Ohm meter the resistances of the SUB-D15 cable connected to the PSD #2. The resistances of the 4 pins is 2.8 MOhm, the grounds and power supplies seems to be in the right position on the connector. We checked also that the ADC LEMO 3 pins connectors pin-out is working.
We connected the cables to the ADC and DAC of the electronic laboratory on site and we checked that the DAC pin-out was correct. The used DAC was a 10V DAC, while on the bench we will have a 20V DAC, so for the test we sent +/-5V instead of +/-10V.
We noticed that the PSD sensor was rotated by 45 degrees with respect to the design of the datasheet. This was taken into account also on the config file of the DAQ, attached here.
To test the PSD we mounted it on a bread board, sending a fiber laser on it through a focusing lens and a steering mirror (as in the attached picture 1).
We managed to reconstruct the signals as shown in picture 2: we moved first in vertical and then in horizontal.
We conclude that the PSDs are working and ready to be installed.
Images attached to this report
Non-image files attached to this report
AdV-DET (Commissioning)
ruggi - 18:41 Wednesday 12 May 2021 (51767) Print this report
Comment to SDB2 - SDB1 issue (51633)

It could be useful to analyse also another event, occurred on April 28, which affected PR and WI top stage control at the same time. In this case the data were not permanently lost as for SDB1, so it could be something totally different. In that case, PR and WI loops stopped working at the same time, and their re-activation required the removal of a NAN from some variable. The source is not known, but I think we can say that, at least for one of the two, the problem arrived from outside. Which doesn't mean 'global control' (LSC_CORR appeared to be zero also in that case), or DAQ. Thinking about the data distribution was a simple answer I gave to me, given that something similar (in the effect) happened days before, in coincidence with a timing problem triggered by an ADC failure at WE (in that case Alain gave in advance a warning about possible drawbacks on GIPC data). The second hint was the fact that a DAQ activity was ongoing (according to the operator).

I'm not doing any diagnosis: just giving information, which I forgot to write in the logbook in the right moment.

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AdV-DET (Commissioning)
bertolini, bonnand - 17:01 Wednesday 12 May 2021 (51761) Print this report
Comment to SNEB large movements (51757)

Romain checked the SNEB_LC controls carefully and concluded that the large TZ displacement was caused by the large X displacement of the MultiSAS (triggered by the large microseismic activity of this morning). It also appeared that the bench was moving substantially more than the ground pointing to some ongoing issue with the top stage controls. Lowering the control gain did not help, so that we decided to disable the inertial control of SBE along X and use only the LVDTs to damp the chain modes and compensate for drifts. After this action we observed a huge reduction of the X motion (Plot1: showing the RMS motion of the bench is compared to RMS motion of the ground for which we took the corresponding SAT F0 LVDT signal.) that was beneficial also, as expected, for reducing the bench angular motion in TZ (Plot3).

In order to further improve the X control we engaged the tracking wrt NE SAT by using the VPM button, but we could not observe any improvement. Therefore we checked the tracking section of the SBE config file and it turned out that the tracking action is still tied to the trigger logic used in O3 based on the arm cavity power. We disabled then the trigger such that now the tracking can be really engaged on the VPM (manually). The effect of the tracking along X can be seen in Plot 2: the error signal (SNEB_F0_x) shrinks significantly and no excess motion of the bench wrt to ground is longer visible. Further work on the SBE controls is needed to improve the performance, especially in Z.

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AdV-DAQ (Calibration)
lagabbe, melo - 16:59 Wednesday 12 May 2021 (51766) Print this report
Comment to Improvement of WE PCal fast process (51738)

The maximum output current of the voltage generator (which supply the photodiodes) is 300mA on each channel. When we increase the power of the laser above 2W, the control loop don't work anymore but the output current of  the voltage generator is aroud 120mW, thus the generator is not saturated. The problem comes from somewhere else.

We opened the control loop and make the laser power command increase from 1.5 to 2W in 30s. As we can see on the figure https://logbook.virgo-gw.eu/virgo/uploads/51766_1620831007_pb_clipping_laser.png the power reflected by the end-mirror measered by Tx_PD1_DC, cannot be above 1.9W even if the command is still increasing. There must be a clipping somwhere.

That is why the control loop is not working when the power command is above 1.8W

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AdV-ISC (Commissioning up to first full interferometer lock)
ruggi - 16:54 Wednesday 12 May 2021 (51765) Print this report
Estimated plant of CARM/DARM loops with B7/B8 error signals

Looking at the data collected on monday morning, with the ITF ready for the hand-off of CARM DARM to B7/B8 sgnals, I tried to estimate the plant of those two loops with the new error signals. The opportunity is given by the fact that the beating signals, in loop at that moment, are enough noisier than the corresponding signals extracted combining B7_DC and B8_DC, so that the transfer functions from the corrections to the out-of-loop errors are directly measurable profiting of this natural noise injection.

The results, shown in the attached plots, are well in accordance with the simplest possible model (1/f^2), and no other evident structure is visible, al least up to 30 Hz. At higher frequency the coherence is low and the result is not totally clear. Anyway, a loop with 20 Hz UGF seems that can be designed assuming a simple plant.

From the measurements, calibration factors for the new signals can be extracted:

-10 for LSC_B7_B8_DC_SUM_SQRT

-20 for LSC_B7_B8_DC_DIF_NORM

Applying those factors to the new signals, the plants should result quite similar to the ones of the beating signals.

All this was already quite obvious, given that the hand-off was already done quite smoothly. It wants to be just an additional information for the development of a robust control to be used at that step.

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AdV-DAQ (Calibration)
lagabbe, masserot - 16:47 Wednesday 12 May 2021 (51762) Print this report
Comment to Improvement of WE PCal fast process (51738)
  • We compare the open-loop and closed-loop-transfert-function of the old loop filter, and the new one:

On all the figures below, the input power is 1.5W + noise, the noise is a noise of 1 mW/sqrt(Hz) below 1kHz and 0.1 mw/sqrt(Hz) above 3kHz

On the figure https://logbook.virgo-gw.eu/virgo/uploads/51762_1620829999_WE_filter_OLTF_CLTF.png : the open-loop-transfert-functions are shown on left and, the closed-loop transfert-functions are on the right. The base filter is in blue and the boost is in purple.

The unitary gain frequency of the base filter is 1kHz, the phase associated is 1.4rad (80°), the UGF of boost filter is 6kHz, the phase associated is 0.4rad (24°)

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AdV-DET (Commissioning)
masserot - 16:45 Wednesday 12 May 2021 (51764) Print this report
Comment to SDB2 - SDB1 issue (51633)

The SUSP_SBE_LC server propagate some Sa channels to some SBE controls (SNEB,SWEB and SDB2) . Here the logfie content of this server when

  • the Sa_OB data  were lost  the 2021-04-27-03h33m44-UTC>WARNING-AcAdcChCheck> Sa_OB_F0_Z - start delayed or missing at GPS1303529641-970704850

  • the Sa_OB data were back  the 2021-04-28-14h24m08-UTC>WARNING-AcAdcChCheck> Sa_OB_F0_Z - Sa_OB_F0_Z delayed or missing from GPS1303529641-970704850 for more or less 125424(s) - nLoop 1254230294@10000Hz

The following plots shows the LSC_{PR,BS,NI,WI,NE,WE}_CORR  channels sent by the LSC_Acl server to each ITF towers and the forwarded one, if any, as SC_{(PR,BS,NE,WE} _MIR_LSC_CORR .  The same data sent to the Sc DSP is sent to the DAQ too .

During these events the ITF was unlocked , as consequence the corrections were at zero and the Sc DSP forwarded corrections remains at zero : so no NAN was forwarded by the Sc DSPs to  the DAQ

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AdV-DET (Commissioning)
bonnand - 16:36 Wednesday 12 May 2021 (51763) Print this report
Comment to SNEB large movements (51757)

The issue of oscillation at SNEB is not due to the 4V on 2 of the vertical coils, we can have up to 10 V on these coils.

Other benches works fine with a similar voltage send to the vertical coils.

We worked on the issue with Alessandro at the end of the morning and we managed to reduced the oscillation of the bench in X, see plot attached .

A detailled entry will be posted later by Alessandro.

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AdV-ISC (Commissioning up to first full interferometer lock)
boldrini, casanueva - 16:00 Wednesday 12 May 2021 (51760) Print this report
ISC shift: CARM offset reduction

The goal of the shift was to test the filter for the hand off to the IR signals and continue the CARM offset reduction.

We began the shift by aligning the green laser on the North arm, but even after reaching what appeared to be a good alignment, we noticed a residual motion of the spot on the photodiode given by a particularly wide oscillation of SNEB on X (Fig.1). We alerted the SBE staff and they concluded their intervention a few hours later.

In the meantime, we tried to do the same with the West arm, but we noticed that while the reflection of the green laser signaled a good alignment, the transmission did not, which suggested a bad alignment of the green laser on its collimator in the laser lab. We alerted the INJ staff, and they finished the recovery shortly after the daily meeting.

Furthermore, the green laser is currently deactivated on NE.

Unfortunately, due to the combination of all of these problems, we were not able to do anything at all during our shift.

We leave the ITF with every node in DOWN, since the TMs on the arms need to be realigned after the intervention in the laser lab.

Images attached to this report
Detector Operation (Operations Report)
menzione - 15:56 Wednesday 12 May 2021 (51755) Print this report
Operator Report - Morning shift

The planned activity on ISC CARM offset, carried out by Boldrini, Casanueva started at 07:00 UTC and went on till SNEB oscillations (large movements) occurred. Experts contacted and fixed the problem at 10:33 UTC.
Meanwhile, according with the crew, the ISC activity has been interrupted at 10:00 UTC to allow ISYS crew to solve a problem on transmission and realign the collimator.
ISYS activities still in progress in Laser lab.

Parallel transparent activities:
- SQZ - Checks in DET Lab, for the whole shift, by Sorrentino 
- SBE - Bertolini tuned a bit the SNEB control on Z degree of freedom from 13:00 to 13:30 UTC.
- DAQ - SQB1 DBOX_Bench, VPN Processes (Masserot from remote) 

Air Conditioning
13:20 UTC - UTA INJ in portata nominale

DAQ
08:27, 09:10 UTC - SQB2 _Fb process crashed/restarted

DET
06:55 UTC - SDB1 in safe position

On-line Computing & Storage
NEB_Eurotherm still unreachable.

SBE
07:17, 09:36 UTC - SWEB PCal laser OFF, under request of ISC team.
09:00 / 10:33 UTC - SNEB oscillations in particular along X degree of freedom. (SBE experts from remote: Bulten, Bonnand, Bertolini)

SBE
(12-05-2021 09:00 - 12-05-2021 09:30) From remote
Status: Ended
Description: SNEB oscillations along X degree of freedom

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AdV-DET (Commissioning)
bulten - 10:57 Wednesday 12 May 2021 (51757) Print this report
SNEB large movements
The operator called me to inspect the large motions of the SNEB bench. I think these are due to the angular control; low-noise is disabled in the SNEB_LC process due to the large-TY error.
However, the vertical coils are above 4 V and the horizontal coils only at 0.7 V. Therefore, this error can only be reset by moving the counter masses on the bench; the vertical back-left and front right coils are at +4.2 and -4.2 V; so the bench has a a tilt both in Tx and Tz. I think the counter masses need to be moved and then the low-noise loop activated.
I asked the operator to contact the LAPP group.
Comments to this report:
bonnand - 16:36 Wednesday 12 May 2021 (51763) Print this report

The issue of oscillation at SNEB is not due to the 4V on 2 of the vertical coils, we can have up to 10 V on these coils.

Other benches works fine with a similar voltage send to the vertical coils.

We worked on the issue with Alessandro at the end of the morning and we managed to reduced the oscillation of the bench in X, see plot attached .

A detailled entry will be posted later by Alessandro.

Images attached to this comment
bertolini, bonnand - 17:01 Wednesday 12 May 2021 (51761) Print this report

Romain checked the SNEB_LC controls carefully and concluded that the large TZ displacement was caused by the large X displacement of the MultiSAS (triggered by the large microseismic activity of this morning). It also appeared that the bench was moving substantially more than the ground pointing to some ongoing issue with the top stage controls. Lowering the control gain did not help, so that we decided to disable the inertial control of SBE along X and use only the LVDTs to damp the chain modes and compensate for drifts. After this action we observed a huge reduction of the X motion (Plot1: showing the RMS motion of the bench is compared to RMS motion of the ground for which we took the corresponding SAT F0 LVDT signal.) that was beneficial also, as expected, for reducing the bench angular motion in TZ (Plot3).

In order to further improve the X control we engaged the tracking wrt NE SAT by using the VPM button, but we could not observe any improvement. Therefore we checked the tracking section of the SBE config file and it turned out that the tracking action is still tied to the trigger logic used in O3 based on the arm cavity power. We disabled then the trigger such that now the tracking can be really engaged on the VPM (manually). The effect of the tracking along X can be seen in Plot 2: the error signal (SNEB_F0_x) shrinks significantly and no excess motion of the bench wrt to ground is longer visible. Further work on the SBE controls is needed to improve the performance, especially in Z.

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