SHIFT GOAL:

The goal was to perform several CC scan at different SR angle. Nevertheless, due the not optimum condition of the MZ and OPA (waiting for the retuning) we decid to perform a couple of scan without changing the SR angle to check the SQZ alignment-

SHIFT activity:

We started at  16:00 UTC and to not interfere with the ITF and risk to unlock, we manually injected the SQZ. 

• System initial status: ITF LOW NOISE 3; SQZ_MAIN @SQZ_Locked_NO_FC

• 16:10:39 EQB1  fast shutter opened (process: SQZ_ctrl/shutter ‘open’)

After that the CC_loop was engaged and then  the AA (process: SQZ_PLL_AA/ Matrix and Filter ‘AA dither enable’).

• started a CC 4MHz phase scan @ 16:52. 

  • time per point = 6 s

  • - initial phase  = 20 degree

  • - final phase = 230 degree

  • - phase steps = 1 degree

  • - random phase = False

  • - Closed shutter sleep time = 120 s

  • - AA closed on dither = False

  • - cc loop gain   = 75000.0

N.B: No glitch during the scan, it was just before and after (see plot)

In meantime Henning checked the MZ and changed lowered again the offset at 0.035 V due to the humidity  misalignment that spoiled the contrast and induced the set point near the actuator saturation. After the Henning action we redid the scan. 

We stopped at 19.25 after that some data have been collected at the CC phase value corresponding to the SQZ and ASQZ, or better to the minimum and maximum values in the BRMS range @210 MHz and in other ranges.

Further data  and plot in the following comments.

Today after the work at  UTA in DET  (# 64079) the squeezed unlocked due to the change of th ehumidity condition (FIG1). I waited for humidity condition recovery to check and try to relock the MZ. It happened at about 10 UtC. I started to check about at 20:13.

Nevertheless on the signal it was and it is present an oscillation with for me not understood origin (FIG2) un. I tried to check the origin but I was not able to find it and understand. I leave the system with the MZ unlocked and tomorrow morning I will contact Henning to check.

Note that the ITF unlock happend when I put in pause the SQZ MAIN automation to work on SQZ system. Maybe it is my fault (FIG3)

I followed the usal procedure to align the MZ and the OPA ( https://logbook.virgo-gw.eu/virgo/?r=56246)

N.B: No walk off was done on the OPA steering to minimize the 01 and thus to improve the alignment. I just mazimized the ratio betweem 00 and 01 by checking the position of the tilting screws on the last steering before the OPA as done inthe past. And check that correspond to the maximum with the upper screw of the previous steering. In this way was not possible really improve the alignment, that require a little bit of walk of between the steering (to plan, if really needed)

This morning we made a first attempt to measure the polarization noise of the NI single bounce beam by using the B5 photodiodes. For this purpose the BS was misaligned in TX in order to send the single bounce beam along the B5 beam path on SDB1 and SDB2. Unfortunately we did not manage to send the NI single bounce beam to the B5 photodiodes, thus the measurement of polarization noise did not take place.

Fig.1 shows the explored misalignments.

Initially Andrea was misaligning the BS in TX only. BS_TX was scanned from ~50 urad (the initial position in NI single bounce) to ~-300 urad. Some beams were observed on the B5 camera when BS_TX was around -90 urad but their power was small. Then Andrea scanned the BS_TY position from -25 to +25 urad, and we could observe a beam of about 3 mW on the B5_PD2 photodiode. This is unfortunately a smaller power than the power we expect on this photodiode if the NI single bounce beam is sent to it (about 12.5 mW). Moreover this beam did not move on the B5 camera when we tried to move NI_TY, while it moved when we rotated WI_TY. This means that this beam was coming from a reflection on WI.

We were not able to find the NI single bounce beam on the B5 camera, but this is probably because we did not explore sufficiently large ranges of misalignment. To be further studied.

The status of the matching of the SC on OPo has been checked.

THe MM > 99%

Dec 22th  morning shift

in the following time is in UTC

• 8:23  we started to open the Shutter on SQB1
• Move ToITF_RetroRef 1200000 step(s) backward in  QB1_Pico.
• N.B: To completely open the shutter we gave more than 2000000 backward. The pico motor has a big hysteresis expecially going backward, so the steps number is not the same in the two directions.
• 8:35 ITF unlock
• 10.14 We asket to Henning to retune the OPA, since the level was lower than the previous day, nevertheless, due to the humidity, during the shift the OPA efficiency continued to decreasy (see attached pictures)
• Mag max 1.49,min 0.58;  after optimization. N.B.: OPA DC max 1.85 V, yesterday was 2.0 Vùù
• 10.53 SQZ tuned and again SQZ_INJECTION
• 10.56 con_scan started   (LOW_NOISE_2)
• We realized that  we cannot use the automatic scan when the SR is completely aligned, since some steps of the process cause big glitches in ITF (the opening and closing the SQZ fast shutter). We decide to go on with the manual injection and phase scan,
• 11.19.40 start SHOT NOISE acquisition  (33.6 Mpc) (SQZ_LOCKED)
• 11.29     stop
• OPerator opened the loop SR_TX and TY before opened the SQZ shutter, to avoid glitches on ITF
• 11.29.30  SQZ_INJECTED (to open the shutter )
• 11.33.54 SR loops closed by operator 
• 11.37.14 manual scan started (from 0.349 rad to 4.01 rad, 1200 s)  (on VPM
• N.B. OPA DC ~1.61 V
  •        SQZ @ 1.6 rad  min 
  •        ASQZ@ 2.77 rad ma MAg 1.2 mV
• 12.14 phi@1.6 rad
• 12.23 phi@2.77 rad 
• 13:49 sr LINE 
• 13:54 manual scan started (from 0.349 rad to 4.01 rad, 1800 s)  (on VPM)

N.B.: DATA to anilize, pictures to add.

Observation: since in the ITF status with the SR completerly aligned at that time did not engaghed  the BS TY loop, relative big fluctuation of the cmrr and thus of BNS range were present. This suggested to perform  slow and longer phase scan for the injection. We were not able to do it at that time, due to the unlock of ITF at the end of the loop, after we realized this issue, Nevertheless the frequency of the peridic glithecd that occur, in any case could compromise the scan.

In the following the procedure for the manual scan

PROCEDURE for MANUAL SCAN with SR aligned (ITF in low Noise two)

N.B.: SInce in this condition the BS is not controlled (check the exat loop that does not work fine), fluctuations in the cmrr and thus in BNS range are induced (frequency ~3 on 5 min)

• Take 10 minutes data (SHOT NOISE)

• Open the SR_TX and TY loops

• Ask in SQZ_MAIN  for SQZ_injected

• Close the SR loops

• On VPM, Squeezer, SQZ_PLL_AA/Fast CC Phase/ B1 4MHz Phase

• Set 0.349 rad with 2s ramp time to set the system at the initial phase

We prepared the system for the squeezing injection:

RR has been rised and realigned to have the maximum SQZ on HD

h 19.45 utc

ASZ 8.4   

SQZ -5.5  (1.95)

Mag max 8.3 mV

Min     2.95 mV  => Pgain =2.81 => 9dB

h 19.47 utc: RR_Y +300000

RR_H/V to maximize mag

Mag_max=8.35 mV, ASZ=8.45;  (phi_CC= 0.87 red )

Mag_min=2.94 mV  SQZ=-5.6  (phi_CC=2.3 rad)  (19.40 utc)

The shift aims to inject the FIS into the ITF. The idea was to work in LOW_NOISE_2 because in this state we had all the LSC dither lines on and all the slow tuning loops of the ITF on. This ITF state was useful during the SR angular position movement. We switched to LOW_NOISE_3 only at the end of the shift.

Preparatory work

• At the beginning of the shift we checked the SQZ level generated with the HD Detector on EQB1, i.e. we measured the EQB1_HD_DIFF_RF_4MHz_mag signal  @UTC 9:36.  (4 MHz_max = 8.34 mV, 4MHz_min = 3.14mV; i.e. 8.27 dB)

• @ UTC 9:42 We rotated the HWP2 on SQB1 to send the SQZ beam toward the ITF.

• @UTC 9:53 We closed the AA loop on B1 4 MHz.

• @ UTC 10:00 The LO was shuttered and the final position of the slow shutter on SQB1 was -1600000 steps to maximize the B1 4 MHz mag.

Problem with the CC phase

When we closed the CC loop and the AA loop of SQZ into the ITF (on B1) we realized that the squeezing phase was unstable. Initially, we suspected a problem in the computation of the demodulation phase by the DAQ. Thus we contacted Alain and we did the following checks:

• We looked at the SQZ_CC_8MHz_mag, dfreq and dphi and we did not notice any problem in the SQZ 8MHz reference readout

• We checked the fluctuation of the CC phase into the ITF by looking the B1_PD1_4MHz_Q and mag and we realized a strong correlation with the SQZ_PumpPhase_Error channel

• We cross-checked also with the EQB1_HD_Detector trying to measure the SQZ level with it but we found the same problem.

• We realized that the pump phase Error signal was not more around zero and that the SQZ_PumpPhase_HV_Monitor channel was not feeding any voltage to the PZT HV amplifiers

• We realized that the PumpPhase Realay on the rack was disconnected. We reconnected it and it started to work all normally

N.B. This issue was because we worked with SQZ_MAIN in READY_FOR_FIS_INJECTION. The right procedure is work with SQZ_MAIN in SQZ_LOCKED

After that, we could properly inject SQZ into the ITF.

FIS Injection with SR aligned

• @ UTC 11:45 We took 5 min of shot noise reference.

• @UTC 11:51 We set the SQZ_MAIN Metatron node in SQZ_LOCKED and we run a CC phase scan with the script /virgoDev/AEI_SQZ/coh_scan.py  (strange not reliable image phase scan01). At the beginning of the scan the filter cavity unlocked and an huge glitch spoiled the sensitivity in the first part. Thus we repeated it.

• @UTC 11:56 we performed another CC phase scan but @12:03 UTC the ITF unlocked during it

• @UTC 13:35 we could perfom a good phase scan (Figure 2). The last part was spoiled by huge glitches. Probably the filter cavity unlocked again. During the scan we measured 4.2 dB of SQZ. We measured between 4.2dB and 5 dB of ASQZ (2.7rad) and between 0.8 dB and 1.1 dB of SQZ(1.3 rad) depending from the observed frequency band

• During the phase scan we looked at the channel SQZ_B1_PD1_4MHz_I_rms that corresponds to the in-loop residual phase noise of the CC loop and we observed that its value changed by more than a factor 2 during the scan (as expected). We tried thus to optimize the gain. We decided to not perform a noise injection (next time could be useful) but we tried to test different gains. Starting from 14:13 UTC we explored a region between 15000 and 100000 and we found an optimal gain at 80000. We did not observe any difference in the Hrec BRMS and in the detected SQZ level. From now on we worked with CC gain =80000 and we saved it in the SQZ_MAIN.ini config file.

• @UTC 14:44:30  we performed another phase scan with the CC GAIN = 80000 and CC dither line off we found a strange behaviour in the data probably due to a glitch and we dropped the data.

• We tried to run another CC phase scan but @15:10 UTC the ITF unlocked

At 15:40 UTC the ITF relocked. We decided to not to perform other phase scan but to take SQZ, ASQZ and Shot noise reference, then misalign the SR mirror (figure 3)

• @UTC 15:59 After 15 min the ITF locked and we started acquiring 2 minutes of shot noise

• @UTC 16:06  Acquisition of 5 minutes in SQZ (1.1 rad) 

• @UTC 16:13  Acquisition of 5 minutes in ASQZ (2.7 rad) 

• @UTC 16:20  Acquisition stopped

FIS Injection with SR misaligned

• @UTC 16:42:50 We started the SR mirror misalignment procedure: we open the SR angular controls and we moved it by steps of 0.1 urad with the GUI. 

• @UTC 17:22 SR misalignment finished (11 steps) TY +1.1urad (Figure 4)

Once the SR was misaligned we used the same phase for SQZ, ASQZ that we used for SR aligned:

• @UTC 17:30 ASQZ injection 2.7 rad( 5 min). We measured about 3dB of ASQZ

• @UTC 17:37 SQZ 1.1 rad (5 min). We measured about 0 dB of SQZ

• @UTC 17:56 we started a phase scan + shot noise reference (Figure 5).

After the scan we left the system with SQZ injected 

• @UTC 18:43  SQZ injection  0.666 rad

• @UTC 18:51  LOW NOISE 3 + SQZ

• @UTC 19:00 ITF Status in autorelock failsafe 

• @UTC 21:36 +0.1urad with SR TY

• @UTC 21:40 0.8rad CC phase

• @UTC 22:12 0.5rad CC phase

• @UTC 22:40 SQZ Off (Figure 6)

• @UTC 22:57 SQZ Injected no CC dither line

At the end of the shift, we realized that the glitches were due to the unlock of FLT and usually were caused by a mistuned threshold (LockFlag) in the automation. We fixed it we changed the maxGR level from 6V to 5.5V in the SQZ_FLT.ini file.

This is a brief entry the full one will follow in the next days.

Today we injected SQZ in normal configuration: SR aligned ando also with SR Misaligned by +1.1urad in TY.

The SR misalignment was completed at 17:22 UTC. Then we started the characterization with Injections and a phase scan.

At 18:43 we started a long run of SQZ injected with SR misaligned

At 18:50 we put the ITF in LN3

At 19:00 UTC we put the ITF STATUS node in autorelock filesafe

The maximum range reached during the injection was 48.8 Mpc.

We left the system in the following way:

• ITF_LOCK: LOW_NOISE_3
• ITF_STATUS: Autorelock filesafe
• SQZ_MAIN: SQZ_INJECTED
• SQB1_Shutter: Open
• SR_TY: Misaligned by +1.1urad 

THis afternoon we prepared the system for the tomorrow injection by checking the alignment of the SQZ on HD (4 MHz maximization from FC and from RR on HD).

We left the RR raised,

ASQZ= 7 dB

4 MHZ mag ~ 7,2 mV

The goal of the shift were:

• Recovery of the alignment after the shutdown and the decrease of the power
• Re-tuning of the automation SQZ_MAIN 
• Tuning of SQB1 and SDB1 HWPs

Actions performed:

• 15:26 UTC SQB1 Shutter Open with -1350000 steps
• We measured the level of SQZ on the HD detector during the opening of the shutter and it was at 4.5 dB and did not change during the opening
• We realized that the SQZ level gnerated by the OPA was very low 7dB.
• We contacted Henning and he retuned the temperature of the OPA
• After the tuning we measured with the parametric gain 7.5 dB of generated SQZ and 4.8 dB of SQZ with HD detector
• At 15:51 UTC we rotated the SQB1 HWP2 to inject SQZ light into the ITF
• The interferometer unlocked and we also realized that the OPA was no more able to relock
• Fiodor spotted that in the DET lab the humidity was very unstable and for this reason the OPA was too Misaligned (Fig1) 
• At 16:28 UTC Henning Changed the MZ offset at 0.05V and we could relock again the OPA. After this tuning we were generating about 8.5 dB of SQZ. During the rest of the shift the level of SQZ was decreasing due to the humidity drift
• After the relock We started to Inject the Squeezing into the ITF: we open the fast shutter and we found the right CC DAC offset that allows us to close the CC loop on B1, i.e 0.285V.
• We started to realign with the CC closed, the SQZ phase in ASQZ, i.e. 2.8 rad and by sending ramps to SQB1_MIRROR1,2_X,Y We could arrive at maximum 0.8mV of magnitude on B1_4MHz
• We tried to move horizontally SQB1 from -3500um to -2850 um and the level of mag increased up to 1.5 mV then the ITF unlocked again
• We profit of this situation to tune the SDB1 OFI HWP:
  • we set the DAC offset at 0.26V to have a beat note on HD between ITF spurious beam and the LO at about 650 Hz
  • we rotated SQB1_HWP_2 to send all the SQZ light again toward HD detector
  • Looking EQB1_HD_DIFF_AUDIO we moved by 100-200 steps per time the SDB1 OFI HWP, in total +550 steps with the aim to decrease the beat note on the spectum
• We did the same with the SQB1_HWP1 waveplate and we moved it in total by -450 steps
• In total we rotated by about 1deg each HWP reducing the beat note on HD by more than a factor 10. All these operation were performed in Carm nulll 1f
• After that the ITF relocked and we were able to close the CC loop gain 25000 and the AA loop reaching a 4MHz mag of about 1.72 mV. 
• We did the following measurements (fig 2 SQZ,ASQZ,Shot in spectrum and fig 3 in time domain):
  • ASQ @ 18:57 UTC phase 2.8 rad
  • SQZ @ 19:02 UTC phase 1.2 rad
  • Shot @ 19:08 UTC
  • We closed the LO shutter at 19:06 UTC
  • SQZ @ 19:23 UTC from shot to SQZ the BNS range increased by 0.5 Mpc
• We retuned also the slow CC loop. The demodulation phase was changed from 5.2 to 4.7 rad and the dither line was increased from 0.0005 to 0.001V
• The ITF unlocked and we tested the automation finding problems in reaching the state ready for FIS Injection. We realized that when the SQZ_CTRL setted the use of the ITF_Status to 1 the SHG unlocked. We modify the Squeezer locking matrix to avoid this.
• After that we where able to inject FIS into the ITF with the automation.
• We set the automation in SQZ_LOCKED and we performed a CC phase scan at 20:45 UTC (fig 4) From the phase scan we realized that the CC dither demod phase was wrong by 90 deg and we put it at 6.2 rad 
• After the phase scan we left the system in SQZ_INJECTED

The recovery of QNR is completed, the measured level of SQZ in the sensitivity was not high but the sensitivity curve was not optimized at high frequencies

We left the shutter open in SQZ_INJECTED. Here the instruction to remove it and close the shutter https://wiki.virgo-gw.eu/AdvancedVirgoPlus/QNRTutorialsSQB1_Sutter

Today we managed to recover the lock of the three PLLs.
First of all we noticed doing an "ll | grep PLL" in the folder ""/dev" of "phasecam1" PC that the MAIN and CC PLL board were not seen by the computer.
Also the DDS board g25squeeze5 was not reachable by remote. Checked doing "ping g25squeeze5"
To solve the problems Fiodor went in DET Eroom on the rack 5 and he switched on and off the PLL board and the DDS board. After that we had also to restart the phasecam1 PC because the PLL was seen as root. 
After that we managed to switch on the VPM server Py_PLL_MAIN, Py_PLL_SC and Py_PLL_CC. Moreover the EQB1_DDS_aux0 was switched on.
Then we noticed that the PDU processes were still off and we restarted them
We noticed allso that the Mach Zhender interferometer of the SQZ source was unlocked and we relocked it.
Finally we put the SQZ_MAIN metatron node in DOWN and we start to lock the PLL.
We noticed that the MAIN_PLL was lockable but toonoise. Thus we decided to lock only SC and CC PLL.
After managing to lock them we tried again to lock the MAIN PLL. The lock was still noise but possible in the right position.
We spotted that the possible problem was due to high noise in the 80MHz reference for the AOM. We asked to Mattieu to check it in INJ_EROOM
He switched off on both the DDS board and the Wenzel and it worked again,

We leave the SQZ_MAIN in FLT_DOWN state.
The new set point of the thre PLLs are in fig 1 

In addition Fiodor switched also on the EDB QPDs and the Rhode and Schwartz generator of EQB1.
Next steps before the relock of the filter cavity is:
- switch on EQB2 Galvos
- update the set points of all the actuators on EQB1 and SQB1 from VPM

Today I restardted the QNR recovery, by carring out the first steps done at the past shut-down (# 60276,  points 1-6, ), that are the electronic reswitching on. THe only point that I did not carried out is the EQB1 and EQB2 QBDs restarting, since it seemed ok. The next day I will check better.

The actuator EQB1_GR_M5 and M7 has been unloaded (M7Y was satureted)

The aim of the shift was to check the performance of the FIS injection with the new B1 PDs

List of the activities:

As first action of the shift we measured the Squeezer parametric gain with the HD detector. We had 9mV max and 2.64 mV min  of HD 4 MHz mag. This correspond to a parametric gain of 3.41, i.e. 10.6dB o SQZ produced by the OPA

At 14:55 UTC we started to open the SQB1 Shutter and to rotate the SQB1 HWP2 half waveplate.

At 15:30 UTC with the automation in SQZ_INJECTED we closed the CC and AA loop and we realigned the SQZ beam toward the ITF

At 15:36 UTC we took the shot noise reference

At 15:44:30 UTC we started a phase scan. From the phase scan we measure roughly 6dB of ASQZ and less than 1dB of SQZ. See fig 1.

We found out that the angle of max SQZ level was 1.2 rad and the angle of max ASQZ level was 2.65 rad.

We measured ASQZ at 16:37 UTC and SQZ at 16:44 UTC. In figure 2 you can see in violet ASQZ, in BROWN shot noise taken at the end of the phae scan (16:10 UTC)  and in RED shot noise taken at 15:36 UTC. In green SQZ taken at 16:44 UTC. You can see that the level of the shot noise is different in both the case.

Thus we decided to take longer data stretches of Shot noise and SQZ:

• figure 3: SQZ ingected up to  17 and 30, than shot noise. You can see that at the beginning the noise in hrec was higher and with a lot of fluctuations. Near the closure of the shutter it was better. When we closed the shutter you can see the step in the noise in Hrec. This is compatible with about 1 dB of SQZ. The cause of the noise was probably an high technical noise in the interferometer. It is also interesting that the 4MHz mag decreased by a factor 2%, but it is not enough to explain the high fluctuations at the beginning of the plot. Moreover are evident some correlation between the movement of SDB1 and the level of the  magnitude, and also some correlation between the coupling of the frequency noise in the ITF (SSFS) and the level of measured squeezing
• figure 4: after the shot noise data we injected again squeezing. The level of the noise in hrec is similar to what we found at the end of the SQZ data in the first part of fig 3.
• At 19 we injected ASQZ and we started to check the alignment, to be sure that the change in the B1 4MHz magnitude was not due to some clipping. We did the following acrions 
  • move SQB1 bench in horizontal X to see inf we could improve the level of the 4MHz mag on B1 (no effect)
  • move the Picomotors on M32 and M33 (small improvement)
  • move the retroreflector on SQB1 (small improvement)
  • optimize the SQB1 HWP1 to decrease the power of the spurious beam from the ITF on EQB1. This was done by looking the beat note of the LO and this beam on HD Detector (open LO Shutter, Put fast DAC offset at 20 mV, rotate SQB1 HWP2 to send all toward HD, improve SQB1 HWP1, come back with SQB1 HWP2)
  • At 20:21 UTC all these operation were concluded
• Figure 5 SQZ (0.9dB at 18:45UTC), ASQZ (5.8 dB at 19:15 UTC), Shot (at 18 UTC).
• Figure 6 the same of figure 5 in time domain

Some observations:

• This time we injected 2dB of more SQZ wrt the last shift. We measure 2dB more of ASQZ but the same level of SQZ (maybe less). We had the impression that the technical noises at high frequency are higher than during the last shift
• Figure 7. Comparison of B1 DC and B1 DC_NULL between new and old PDs. In the case of B1_DC null the noise is lower because the dark noise of PDs is lower, but B1_DC has the sane level. This seems due to the fact that the high frequency was not limited only by the dark noise of B1 PDs. Now the distance between B1_DC and B1_DC_NULL is higher wrt the older PDS, See fig 8.
• We checked also the noise in Hrec during the last night, no SQZ inkected. And you can see that the level of hrec had oscillations compatible with an injection of 0.8 dB of SQZ (Fig 9). All these are probably evidence that we are still not shot noise limited.
• When we removed the SQZ the sensitivity dropped of about 1 Mpc. Some effect is visible (fig 10)

We left the system in SQZ_INJECTED and the shutter open on SQB1. We are injecting SQZ all the night (fig11 preliminary data). At 21:15 UTC we closed the SLOW CC Loop (we forgot before) and we increase the CC gain from 20000 to 35000 (we did not update this value in SQZ_MAIN.ini file)

To remove SQZ injection put SQZ_MAIN in ready for FIS injection and close SQB1 shutter: (SQB1 pico, PM34_NC by plus (800000-1000000) steps)

On Wednesday morning we replace the silicon wafer for the dust contamination on

• EQB1:  vertical and orizonthal near the HD (there are not other samples on EQB1)
• EDB: vertical and orizonthal sample

Yesterday morning the Mach Zehnder in the SQZ BOX has been  realignment foollowing the same procedure described in 60285 and in 56246. Again was sufficient to act only on the lower red knob of the MZ mirror shown in the first picture of 56246.

Attached the results.

SC on OPO alignment

Misalignment measured: ~ 1.5 % (see attached plot)

It is visible on the HD_cams: where the relative position of the LO and SC on them is shown.
(The AA loop maximize the overlap between the SQZ beam and LO).

Due to the lowering of the FC green transmission in long time,we decide to check the AOM alignment.

The power at the out of EQB1 FI was about 21.4 +/- 0.2 mW against the about 24.5 mW that we had in the past, after the last AOM optimization.

https://logbook.virgo-gw.eu/virgo/?r=54093

I reoptimized the alignment having the following power budget of the green on EQB1 (+/- 0.2 mW) :

• GR    input AOM                 45,5 mW
• GR    single pass AOM       32.2  mW 
• GR    input FI/double pass   27.1 mW 
• GR    input FI/double pass  25.5 mW 
• GR    output FI                     24,8 mW  

Just after, I discarged the GR BPC actuator, M5 and M7 (V=0 V for all) and I  realignment of the FC, reaching a maximum in trasmission   FCEB_GR_PD~6.95 V

Nevertheless by engaging the AA, the trasmission was lowered to 6.67 V.  I tried to recovery the maximum acting on SQB2M1 an SQB1 M11, but  without success .I had not a lot of time to do this, so further action are needed.

This morning we installed and tested the shutter on SQB1. The shutter was installed between the last mirror and the windows towards the detection bench (red circle in fig 1).

First of all, we weighed all the components to counterbalance the weight:
1045 g shutter + cable + screws
90g clamps
190 g beam dumper (to trap the back reflection)

total weight: 1325g

Removed counterweight 2018 g, 221 g, 28g
Added counterweight 942 g

We put the automation in DOWN and we opened the SC. We rotated the HWP 2 on SQB1 (+18000 steps) to have a transmitted signal from the FI and intercept the beam with the new shutter.
After centering the shutter we tested it moving up and down:

starting point 96 mm 

-600000 steps: 86 mm (negative steps remove the shutter)
+700000 steps: 97 mm (positive steps raise up the shutter)
-600000 steps: 89 mm

We recommend always +-700000 steps to raise up and remove the shutter.

Yesterday afternonn we opened SQB1 and  mounted the dedicated blocking system. WIth the latest,  we also recover the bench alignment  to prepare the shutter installation (beam in the right position  to be injected in  ITF is s needed ) and the centering of the SQB1 cameras.

Aafter the black out  on Thursday 18th  and  Monday 22th May and  after the OPA and MZ realignment   (# https://logbook.virgo-gw.eu/virgo/?r=60285), we continued witht the system recovery on Tuesday 23th aftrnoon and wednesday 24th morning, i.e.:  HD alignment from FC and DL.

We remember that the standard procedure to align the HD is  first to align the beam from FC on HD by acting on  HD_M5 and M6  mirrors (M4 is used for the CC loop),  common to all the three available paths  (from FC, from RR and from DL)    and then to align  the DL mirrors (DL_M4 and M5 on VPM EQB1_ThorAct, DL_M2 and M7 on the Optocad scheme attached) to  overlapp on the HD  the  beam coming from DL path with the LO. In other words, the referece position for the HD mirrors M5 and M6 are given by the beam coming from FC. Moreover this beam fix even the position fo SQB1_M13 mirror that send the beam from SQB1 to EQB1_M6  (N.B:   HD_M6  can be remotely aligned by VPM, EQB1_HD_AA; HD_M5 by VPM EQB1_ThorAct, SQB1_M13 by VPM SQB1_pico) .

For this reason, before to proceed on the DL alignment, we recovered the IR alignment on FC, the SC on OPA and then the alignent on HD both from FC and DL.

SC on OPA alignment

The squeezer was in BAB mode, i.e. locked on orthogonal polarization (p-pol). To perform the alignement  we put the OPA in p-pol scan and locked to  the SQZ_OPA_PD_DC channel,since the relative PD is sensitive to the SC transmitted by the The SC was completely misaligned (see pictures SCvsBAB that show the relative position od the BAB ans SC on HD). This correspond to null  beating signal on  EQB1_HD_RF_DEMOD DataDisplay channel (signal from the  the photodiode placed ijust after the EQB1_FI when the IR shutter (the shutter is a mirror that deviates the IR from the main squeezing path to this photodiode). In this situation was not possible recovery the alignment by acting by renote on the SC_M1 and M2 piezo by VPM (SC_M1 and SC_M3 on VPM EQB1_HD_AA, respectiviely), but an on bench intervation was needed. Due to this, the SC_M1 and SC_M2 piezo were unloaded, by putting all to 0 V) An alignment of less then 1% (~0.8 %) was reached. COrresponding the RF signal on PD_RF_DEMOD passed from the dark value of about 4.4 V to the minimum of ~ 1.8 V

N.B: SC_M1 and SC_M3 piezos saturation @ 5V (no beam shift observed for voltage > 5 V)

BAB reflected by FC on HD

After the OPA relignment, the IR on FC was completely misaligned. We proceeded as usual (see comment to this report), first by looking to the reflected beam from the FC on EQB2_IR_PD and Cam and to the IR transmission.

Before to proceed with the  HD realignment, we restored the IR alignment on FC,  with  the BAB plus  SC in trasmission @ ~14.2 V ( TEM00 peak @ 'SC PLL frequency = 100092300   (VPM, EQB1_DDS_PLL ).  The Hd alignment was done using only the BAB and as usual, first, by   overlapping it on LO on HD_FF_cam and NF_cam and then by maximizing the HD contrast on EQB1_PD_MONI and HA_PD1, using EQB1_M6, M5 and SQB1_M13 (FIG2-4). We do not performed the fine alignment, since it can be done in SQZ mode with the 4 MHz beat amplitude mazimization.

BAB  by DL  on HD alignment

The alignment of the DL required an 'on bench operation' to restore the beam on all the mirrors (it was yet out after the third). This operation was done Tuesday afternon, in the time slot 16.00-17.15 cest. Then a  fine overlapp to the LO on HD to maximize the CNT was done by remote acting on VPM, EQB1_ThorAct, DL_M4 and DL_M5 - corrisponding to DL_M2 and DL_M7 on the attached OPTOCAD scheme - (FIG5 and 6).

THe DL were not yet recovered after the additional  EQB1 leg installation, so that it was completely misaligned to require the by hand on bench operation. Since our reference for the HD mirrors is after the OPA relignment even the IR On FC required alignment and

• N.B.: DL  ON/OFF: on VPM it is possible to insert or remove the DL with a bottom. Sometimes it does not work and we have to act via terminal by connecting to  'telnet apusqueeze1 5000'. Remember: DL OFF: position 0; DL ON: position -50)

Squeezer translational stages

during the squeezer alignment we have experienced communication errors between the PI_stage processes and the actuators. AEI team used the PI GUI under Windows virtual machine for the alignment.

We will take the opportunity for the debug and migration of the PI_stage process. Luca agreed to lead the migration process.

Any test involving the squeezer actuators  should be discussed with the AEI team. Before a test which risks to move randomly the actuators, all lasers must be shut down to avoid sweeping laser beams randomly over components inside the box.

MZ realignment:

       This morning we proceeded with the realignment of  the squeezer pump power MZ stabilizer   as  did one year ago (#https://logbook.virgo-gw.eu/virgo/?r=56246) and the OPO tining.

       The starting state for MZ was with a contratrast from  ~0.7 Vp-p to ~ 1.6 Vp-p around the mean value of 1.2 (see attached plot).

We acted again on the same actuator (see pictures in

OPA tuning

        Then we proceeded with the OPA. In this case, maybe due to the humidity state,we were not able to improuve the alignemnt. We decide to leave the system as it is and wait for the humidity (more) and temperature observaton in the next two weeks  to eventually act again. (Only the screws on the last steering before the OPA were moved - see picture in #https://logbook.virgo-gw.eu/virgo/?r=56246 )

Rough extimation comparing the peak to peak power:

• OPA misalignment: ~ 7%
• OPA mismatch: ~ 1%

P.S:: Before to start a problem on the remote control of the squeezer translational stages was solved (a dedicate report will follow)

The recovery of QNR system after the electrical blackout was performed on Thursday 18 May and Monday 22.

The following electronic was reswitched on:

1. Squeezer Main Laser, Squeezer CC Laser and EQB1 Subcarrier Laser
2. The 4 DDS box on the rack 5 (restarted off-on to update the IP address): g25squeeze4, g25squeeeze5, g25squeeze5 and g25squeeze7
3. The EQB1, EDB and EQB2 QPDs were restarted, both the BIAS and the Power supply
4. The 80MHz generator for the phase camera+PLL AOM was restarded via g25squeeze2 DAQ BOX
5. The 80 MHz generator used for the Main PLL was re switched on with the following parameters:
   • Frequency 80 MHz
   •  Amplitude 0 dBm
   • Frequency modulation External
   • Frequency modulation DC
   • Frequency modulation slope 44 kHz
6. The 78 MHz generator used for FMODERR loop was restored with the following parameters:
   • Frequency 78.919655  MHz
   • Amplitude pk-pk 0.9V
   • Modulation FM
   • Tuning range 600 Hz
   • Remember to switch on the output and the modulation (both the led below buttons should be on)

Part 1 - The suspended benches and mirrors are controlled again:

On thursday 18 the first action performed was the control of SQB1, SQB2, FCIM, FCEM

• SQB1:
  • we checked in the VIM the position of the DOF and we found that the setpoint in the config file were not updated in particular LC_X -3700 (last position) and LC_Y -550 (last position), we saved in the config file LC_X and we updated online LC_Y (still not saved)
  • we opened the tracking loop (SDB1 was uncontrolled)
  • we closed the angular controls
  • we closed the position controls
• SQB2: 
  • position are checked and are ok
  • we opened the tracking loops
  • closed the angular controls
  • closed te position controls
• FCIM, FCEM: 
  • with a trend we found the last position of FCIM and FCEM MAR_TX and MAR_TY when the cavity was aligned and we set it online
  • we closed the Local controls MAR_TX, MAR_TY and MAR_TZ
  • we closed the position controls of the inverted pendulum

On Monday 22 May we closed again the tracking loops of SQB1 (once SDB1 was controlled) and SQB2 once (NI was controlled). We aligned also the filter cavity maximizing the flashes in transmission.

In the meantime Henning rechecked the squeezer and the BAB was restored. A problem on SQZ Translation stages occured we could not move them anymore (up to now we can not switch from BAB to SQZ)

Part 2 - Recovery of PLLs

• Until the recovery of the INJ system we could only try to lock the CC and SC PLLs:
  • CC PLL: once restarted the CC laser it worked at the first attempt (SQZ_MAIN in LOCKED_PLL_CC _STAND_ALONE)
  • SC PLL: was not working thus we realized that the hardware was still off. Once we also switched off-on the noise eater 2 times and we could lock the PLL at the first attempt
  • MAIN PLL: once the RFC was locked we performed the following actions
    • Try to lock the PLL without succes
    • With the MUX out we checked the value of LO and RF input (looking the EQB1_MAIN_PLL_STATUS). For the LO we had a good signal for RF no. 
    • We disconnected the LO cable and we realized that was the generator. So RF cable is the beat note this means that the beat note was not present
    • We checked the Photodiode EQB1_MAIN_PLL_PD1_DC and PD2_PDC and we realized that a part of the power was missing probably the pick-off of the inj laser
    • ALS was present thus the beam in the fiber was present, thus after some investigation and with the help of Mattieu we realized that probaby the RF generator of the PLL+Phase camera AOM was not restored
    • I reconfigured the channel 1 of the g25squeeze2 DDS at 80 MHz 
    • After that we regained the missing power on the MAIN_PLL_PD1_DC and PD2_DC and the PLL locked at the first attempt

Part 3 recovery of the filter cavity

• Once the three PLLs were locked again we realigned the filter cavity and we relocked it. A huge noise was present thus we forced in the SQZ_CC_Ctrl process the filter0, the FC_Error signal based on GR_PD 
• The Filter cavity relocked but once we engaged the AA the filter cavity misaligned
• After some investigations we realized that no power on EQB1 QPDs was present. Thus we asked to Fabio to check if the QPDs were on after the ENEL Failure. He reswitched on all the QPDs and the AA worked again
• We put a Scan on PLL SC and we unlocked and relocked the cavity until we found SC flashes in transmission
• We maximized the SC flashes in transmission closing the PY_SQZ_IR loop using SC_PLL as actuator
• We closed IR_AA loop
• We manually closed the FMODERR loop and helping it putting a DC offset od 3.2V then we removed it with a120s ramp
• We performed FMODERR and we reached the state FLT_IR_AA_FMODERR_TUNED. We set 0 Hz detuning in SQZ_FLT.ini for FMODERR
• We religned SC into OPA using the SC AA loop
• We maximized the tranmission of the SC into OPA using M21 and M22 with the IR AA closed. We reached again 14.7V of IR transmission BAB+ SC, i.e. 13.6 V of SC and 1.1V of BAB
• We left for the night the filer cavity in loked IR_AA FMODERR_TUNED

Still to do:

• Update the setpoint of SQB1 MIRROR1 and 2 after the blackout
• Update the demodulation phases of SQB1 AA loop with ITF
• Realign the HD detector with SQZ beam
• The reflected beam from FLT seems clipped on EQB1 cam, to be checked
• The SQZ translation stages are still not working