ITF found DOWN and in UPGRADING Mode.
All times are UTC.
Below the activities comunicated to the Control Room:
07:32 - 10:49 NI payload assembly (Majorana, Pinto).
10:12 - 10:34 RFC Scan (Spinicelli from remote).
12:00 - 12:11 IMC Scan (De Rossi from remote).
12:26 - 12:55 Check of Newtonian Sensor at NEB (Tringali).
As soon as the power went out the first time and the ventilation system shut down, Piero Chessa and I immediately left the clean room to avoid causing any problems. When the power came back on, the ventilation system restarted, and we were trying to figure out what to do (again from outside the clean rooms) when the power went out a second time. After about 5 minutes, it came back on, but this time the ventilation system didn't restart. So we left the central building and went to the control room, where they reported no problems with the central building's ventilation system.
At this point, Davide Soldani was called, and we went with him to the central building where he had to manually restart the ventilation system. At this point, we decided to suspend all operations until the next morning to allow the clean rooms time to return to a stable state.
We continued to deploy the DAC1955 v3r3 firmware on all the DAC1955 boards use the SQZ system and driven by
- rtpc3 : the 11 DAC1955 boards have been updated
- Tolm output data flow is reduced from 37.7MB/s to 12.MB/s
Operations performed between 2026-07-08-11h36m47-UTC and 2026-07-08-15h54m33-UTC
- all the loops were opened during the time of the operations
- we checked that all the DAC1955 Tolm packets are well received by the expected DAC1955 board
- the SQB1 LC loops were successfully closed after the update . The SBE ones were not closed before the upgrade
- The FCEM LC and SBE loops were successfully closed after the update
- The FCIM LC and SBE loops were successfully closed after the update
Below the detailled list of the operations performed
- Use DaqBox v17r11 for SQB2_dbox_bench, SQB2_dbox_rack, FCEM_dbox and FCIM_dbox
- SQB2_LC server : 3 DAC1955 boards
- SQB2_DAC_PSD : DAC1955_SN161 - DBOX_SN108 - SQB2_dbox_bench : rtpc3
- SQB2_DAC_LC_LVDT_in : DAC1955_SN049 - DBOX_SN107 - SQB2_dbox_bench : rtpc3
- SQB2_DAC_LC_LVDT_out : DAC1955_SN150 - DBOX_SN096 - SQB2_dbox_rack : rtpc3
- We checked that the Tolm packects are correctly received by the DAC boards
- the SQB2_LC loops were successfully closed after the upgrade
- SQB2_SBE and EQB2_QD servers : 2 DAC1955 boards
- SQB2_DAC_SBE0 : DAC1955_SN152 - DBOX_SN095 - SQB2_dbox_rack : rtpc3
- SQB2_SBE server : ch00-ch03 : 4 channels
- EQB2_QD server : ch04-ch05 : 2 channels
- EQB2_DAC_IR_GALVO : DAC1955_SN122 - DBOX_SN110 - SQB2_dbox_rack : rtpc3 : all the channels are managed by the EQB2_QD server
- We checked that the Tolm packects are correctly received by the DAC boards
- It remains to check that the galvo loops are still running correctly
- SQB2_DAC_SBE0 : DAC1955_SN152 - DBOX_SN095 - SQB2_dbox_rack : rtpc3
- FCEM_LC and FCEM_SBE servers: 2 DAC1955 boards
- FCEM_DAC_LC0 : DAC1955_SN013 - DBOX_SN068 - FCEM_dbox : rtpc3 : all the channels are managed by the FCEM_LC server
- FCEM_DAC_SBE0 : DAC1955_SN127 - DBOX_SN069 - FCEM_dbox : rtpc3 : shared DAC board
- FCEM_SBE server : ch00-ch03 : 4 channels
- FCEM_LC server : ch04-ch07 : 4 channels
- We checked that the Tolm packects are correctly received by the DAC boards
- The FCEM LC and SBE loops were successfully colsed after the upgrade
- FCIM_LC and FCIM_SBE servers : 2 DAC1955 boards
- FCIM_DAC_LC0 : DAC1955_SN143 - DBOX_SN024 - FCIM_dbox : rtpc3 : all the channels are managed by the FCIM_LC server
- FCIM_DAC_SBE0 : DAC1955_SN125 - DBOX_SN073 - FCIM_dbox : rtpc3 : shared DAC board
- FCIM_SBE server : ch00-ch03 : 4 channels
- FCIM_LC server : ch04-ch07 : 4 channels
- We checked that the Tolm packects are correctly received by the DAC boards
- The FCIM LC and SBE loops were successfully colsed after the upgrade
- Unused DAC1955 boards : 2 boards
- FCEB_DAC_00 : DAC1955_SN014 - DBOX_SN045 - FCEM_dbox : rtpc3
- FCIB_DAC_00 : DAC1955_SN033 - DBOX_SN112 - FCIM_dbox : rtpc3
This morning I measured the modulation index of the 6MHz and 56MHz after the work on INJ/ALS started on April.
I started scanning the RFC with the INJ in standalone at ~10.21.30UTC , by moving the MC on F0_Z axis for a 500µm displacement in 500µs , as usual.
The resulting modulation depth for the 6MHz and 56MHz are, respectively, ~0.19 and ~0.18, which correspond to the usual values.
We continued to deploy the DAC1955 v3r3 firmware on all the DAC1955 boards use the SQZ system and driven by
- the rtpc2 : the 9 DAC1955 boards are updated
- Tolm output data flow is reduced from 37.7MB/s to 8.4MB/s
Operations performed between 2026-07-08-05h59m01-UTC and 2026-07-08-09h22m32-UTC
- all the loops were opened during the time of the operations
- we checked that all the DAC1955 Tolm packets are well received by the expected DAC1955 board
- the SQB2 LC and SBE loops were successfully closed after the update
Below the detailled list of the operations performed
- Use DaqBox v17r11 for SQB1_dbox_bench, SQB1_dbox_rack and EQB_QD_dbox_rack
- SQB1_LC and SBE servers : 4 DAC1955 boards
- SQB1_DAC_PSD : DAC1955_SN120 - DBOX_SN103 - SQB1_dbox_bench : rtpc2
- SQB1_DAC_LC_LVDT_in : DAC1955_SN135 - DBOX_SN103 - SQB1_dbox_bench : rtpc2
- SQB1_DAC_LC_LVDT_out : DAC1955_SN144 - DBOX_SN088 - SQB1_dbox_rack : rtpc2
- SQB1_DAC_SBE0 : DAC1955_SN147 - DBOX_SN087 - SQB1_dbox_rack : rtpc2
- We checked that the Tolm packects are correctly received by the DAC boards
- The SQB1 LC and the SBE loops were successfully closed after the upgrade
- SQB1_FI server : 1 DAC1955 board
- SQB1_DAC_01 : DAC1955_SN151 - DBOX_SN088 - SQB1_dbox_rack : rtpc2
- We checked that the Tolm packect is correctly received by the DAC board
- EQB1_QD server : 1 DAC1955 board
- EQB1_DAC_03 : DAC1955_SN148 - DBOX_SN091 - SQB1_dbox_rack : rtpc2
- We checked that the Tolm packects are correctly received by the DAC boards
- It remains to check that the galvo loops are still running correctly
- EQB1_HD_AA server : 2 DAC1955 boards
- EQB1_DAC_01 : DAC1955_SN149 - DBOX_SN089 - SQB1_dbox_rack : rtpc2
- EQB1_DAC_02 : DAC1955_SN146 - DBOX_SN091 - SQB1_dbox_rack : rtpc2
- We checked that the Tolm packects are correctly received by the DAC boards
- EDB_QD_AA and EDB_QD_MM servers : 1 DAC1955 board
- EDB_DAC3 : DAC1955_SN119 - DBOX_SN075 - EDB_dbox_rack : rtpc2
- EDB_QD_AA server : EDB_DAC3 : ch00-ch03 : 4 channels
- EDB_QD_MM server : EDB_DAC3 : ch04-ch07 : 4 channels
- We checked that the Tolm packect is correctly received by the DAC board
- It remains to check that the galvo loops are still running correctly
- EDB_DAC3 : DAC1955_SN119 - DBOX_SN075 - EDB_dbox_rack : rtpc2
We continued to deploy the DAC1955 v3r3 firmware on all the DAC1955 boards use the SQZ system and driven by
- the rtpc23 : 1 DAC1955 board updated
- Tolm output data flow is reduced from 4.2MB/s to 0.42MB/s
- the rtpc1: 2 DAC1955 boards updated
- The total Tolm output data flow reduced from 54.5MB/s to 11MB/s
Operations performed between 2026-07-08-05h14m16-UTC and 2026-07-08-05h44m40-UTC
- all the loops were opened during the time of the operations
- we checked that all the DAC1955 Tolm packets are well received by the expected DAC1955 board
Below the detailled list of the operations performed :
- Use DaqBox v17r11 for SQZ_DBOX_DET_EERoom server
- SQZ_PLL_AA server : 1 DAC1955 board
- SQZ_DAC2 : DAC1955_SN032 - DBOX_SN058 - SQZ_DBOX_DET_EERoom : rtpc23
- we checked that the Tolm packect is correctly received by the DAC board
- SQZ_CTRL server : 2 DAC1955 boards
- SQZ_DAC0 : DAC1955_SN070 - DBOX_SN092 - SQZ_DBOX : rtpc1
- SQZ_DAC1 : DAC1955_SN112 - DBOX_SN093 - SQZ_DBOX : rtpc1
- we checked that the Tolm packects are correctly received by the DAC boards
We left CEB clean room at 12:50 LT.
Erratum: The mirror used to align the master laser with the SL cavity is LB_M1, not LB_M2. Horizontally, the screw was turned anti-clockwise, and vertical screw was turned clockwise. The final linearity bandwidth after re-alignment is 1.9 MHz, not 1.0 MHz.
The method used to measure the linearity bandwidth of the slave laser is expalined in post 66249.
We are entering again the CEB clean room. 9.30 LT
We left CEB clean room at 12:50 LT.
We left the CEB clean room at 21.00 LT. Tomorrow morning we will continue.
Before measuring the locking bandwidth, the OLTF of the IMC was measured, and a 14° phase margin was measured.
We measure the locking bandwidth, which is the linearity zone between the SL cavlty length and the error signal. Initially, it was measured at 0.9 MHz
After turning the LB_M2 mirror horizonally, we managed to increase the bandwidth up to 1.3 MHz. After that, we measured the IMC OLTF again, and found a 19° phase marging.
After that, we tried to realign LB_M2 vertically, we managed to reach a 1.0 MHz bandwidth. The UGF of the IMC OLTF was 92kHz with a 23° phase margin. In order to increase the UGF, we diminished to IMC loop attenuator value from 11dB to 9dB, which increase the main gain of the loop. The new UGF is 120kHz with a 20° phase margin. The two plots shows the OLTF of the IMC with the attenuator at 11dB and at 9 dB.
Other subject: In order to stabilize the TY degree of freedom EIB, we moved the the water tubes of IPC1. It improves the TY value and releases a bit the actuator 0.
Erratum: The mirror used to align the master laser with the SL cavity is LB_M1, not LB_M2. Horizontally, the screw was turned anti-clockwise, and vertical screw was turned clockwise. The final linearity bandwidth after re-alignment is 1.9 MHz, not 1.0 MHz.
The method used to measure the linearity bandwidth of the slave laser is expalined in post 66249.
ITF DOWN in UPGRADING mode.
planned activities communicated to the control room:
- Realignment of Master Laser wrt Slave Laser, OLTF measurements (Gosselin, Lagabbe)
- WI tower baffle installation (Ballester, Erbanni, Francescon, Gherardini)
- EIB step-motor adjustment. EIB - SAS motor control not responding, issue temporarily fixed but if will be addressed again by Bertolini during the next maintenance (Bertolini, Carbognani, Gosselin)
Figure 1. The B4 phase camera has an apparent offset in the sideband power measurement when no light and no reference beam is present on the phase camera. The offset is around 25e-6 in the not normalized channels. This offset has been present for at least the past three years, and has been relatively stable over that period.
Figure 2. That offset is comparable to the sideband power in single bounce, especially when the input power is low, as in this example with 11W of input power. The signal of the phase camera for the 6MHz increases only by a factor 2, in the single bounce configuration, compared to the dip in the middle which is at 25e-6 corresponding to no beam arriving on the phase camera.
If that is a real offset, then in single bounce the power of the sidebands is overestimated by a factor, and the sideband gain is under estimated by a factor 2. It would also affect the measurement of the sideband modulation depth that use single bounce beam data and the ratio between the sideband and the carrier power as measured by the phase camera.
Analyzing data from the reference period at 11W used in the O4 detector paper (VIR-0710G-24), on Dec 10, 2023. The 6MHz modulation depth without compenstating for the offset is 0.21, while by subtracting the offset it becomes 0.15. However, the modulation depth measured simultanously with the B1p camera is 0.19, much closer to the value without subtracting the offset, and the B1p camera is not affected by the offset issue because the power is much higher, so the offset is always negligible compared to the sideband power in single bounce.
Similarly the 56MHz sideband has modulation depth of 0.21 on B4 without correcting for the offset, and 0.14-0.16 after correcting for the offset, while on the B1p phase camer it is 0.19-0.20.
/users/mwas/PC/PC_modulation_depth/SB_mod_depth.m
Figure 3-5 The OMC was scanned a few days later on Dec 19. The carrier TEM00 power is 0.0272 and the 56MHz sideband power is 0.29e-3, which correspond to a modulation depth of sqrt(4*0.29e-3/0.0272) = 0.206, which agrees with the B4 phase camera measuremetn without offset correction.
It appears that the offset visible in the phase camera does not affect significantly the sideband power measurement despite the offset being equal to half of the sideband power measured value on a single bounce beam.
Looking at the phase camer code and raw data, this offset is likely the average value of numerical noise.
Figure 6 shows the raw phase camera data at a time when no beam is present, and it is clearly a digital noise with an integer number of counts between 0 and 3. Looking at the computation of the sideband power in /virgoApp/PyALP/v3r0/src/main.py, it is the average value of the square of that channel over one second.
Figure 7 for comparison shows the same raw data when the interferometer is full locked. This is only available in raw full data so we do not have recent data, but there were some times which have been archived. I did not search the archive extensively, but I do not expect we have archived single bounce raw full data. The power of the sideband in single bounce should be a factor 5e-2*0.5^2/20 smaller, where 5e-2 is the PR transmission, 0.5 the BS reflectivity and 20 the sideband gain, which means the amplitude as measured by the phase camera should be a factor 40 smaller in single bounce than with a full interferometer, corresponding to up to 15 counts. Given that the average is looking at the square of the PC raw channel, mostly the times when the value is large count in the average, and these will be less affected by a digital noise of a few counts around 15, especially if that noise becomes symmetrical once the signal is no longer at the zero rail of the digital output.
This might be an explanation why the offset is not affecting so much the measurement of the sideband power, but that depends on how that digital noise behaves when there is a small but not zero signal. It will be easier to confirm once we get back a single bounce beam to have access to PC raw data in single bounce.
Luca, Angelo and Fabio are entering the WI tower to install the 'tower baffle'
- DAQ: SQZ new DAC1955 firmware update;
As soon as the power went out the first time and the ventilation system shut down, Piero Chessa and I immediately left the clean room to avoid causing any problems. When the power came back on, the ventilation system restarted, and we were trying to figure out what to do (again from outside the clean rooms) when the power went out a second time. After about 5 minutes, it came back on, but this time the ventilation system didn't restart. So we left the central building and went to the control room, where they reported no problems with the central building's ventilation system.
At this point, Davide Soldani was called, and we went with him to the central building where he had to manually restart the ventilation system. At this point, we decided to suspend all operations until the next morning to allow the clean rooms time to return to a stable state.
On July 6, we tried to improve the AOM alignment by turning the LB_M10 mirror, located just before the AOM on the laser bench. The first order beam power generated by the AOM was measured using a calorimeter. The PCM was re-aligned. We managed to get 2.6 W on the 1st order beam. The setup to measure the 1st order power is shown in the following image.
It is not clear if we were actually improving the 1st order power, since the separation between the 0th and 1st order as small. We though that the 1st order beam was clipped by the prism located just before the PMC. We tried to move the prism, in order to make sure that the whole 1st order, and only the 1st order beam arrives on the calorimeter.
This reduces a bit the RMS of the PSTAB_PDd_AC photodiode signal. However, we still don't know if the improvement was due to a better alignment in the AOM, or if the PMC alignment was improved.
On july 7,
The oltf of the pstab was measured using the spectral-analyser application of the Moku-Pro. The Moku generates a chirp signal whose amplitude and frequency range can be tuned by the user. The chirp signal was injected in the "perturb" channel.
Initially, the UGF was measured at ~45kHz. By turning the "piezo gain" controller in the image below, we increased the gain of the loop, and so the UGF. The new ugf value is 67kHz, with a 60° phase margin.
The morning was dedicated to weekly maintenance started at 6:00UTC, here a list of the activity reported to the control room:
- standard vacuum refill from 6:00UTC to 10:00UTC (VAC Team);
- cleaning of central building (Menzione with external firm: from 6:00UTC to 10:00UTC);
- PAY: NI payload assembly;
- INJ: IMC lock/alignment commissioning, in progress;
Air Conditioning
at around 7:55UTC I put back the injection area air conditioning system in "portata ridotta", I set back the "portata nominale" at 13:55UTC.
On July 22 the INGV team (Filippo Greco, Alfio Alex Messina, Luca Timoteo Mirabella) with the EGO support (Lorenzo Lunghini, Fabrizio Rossi) will install the quantum gravimeter (presently at 1500W fiber lab: https://logbook.virgo-gw.eu/virgo/?r=68692) inside the WEB experimental hall. The foreseen location is along the South wall of the building. The operation might take the entire day.
Yesterday I recovered a bit the SQZ system in view of the DAC firmware upgrade.
1) PLLs. I managed to lock only CC PLL. SC PLL need a check from site, I don't finde the beat note remotely. Main PLL: in order to relock it we shoulde change by about 2GHz the frequency of all the SQZ laser, because according to INJ crew the last FMODERR tuning moved by 1.2mm the end mirror of IMC. This is a longer work because we should also check if the CC laser in the new position will have again multimode behaviour. I did not do it yesterday
2) HD AA, and CC loop. Are perfectly working and we managed to measure 8.5dB of ASQZ and 6dB of SQZ deflecting the SQZ beam on SQB1 retroreflector
3) FCIM, FCEM and SQB1 bench are recovered both position and angular loops.
Some sidenotes:
After the upgrade from cent OS to Alma Linux I had to partially rewrite all the SQZ GUIs because the PyQt4 now are no more available. I did the porting to PyQt5
Olwin does not work now anymore. It works only on ctrl1
ITF DOWN in UPGRADING mode.
planned activities communicated to the control room:
- 08:20 - 10:10 UTC - NI tower baffle repositioning (VAC team, Gherardini)
- 13:50 UTC - BPC and IMC loops recovery activity in Laser Lab (Spinicelli, LaGabbe, DeRossi). UTA INJ set in Portata Nominale.
We continued to deploy the DAC1955 v3r3 firmware on all the DAC1955 boards used from the rtpc6 .
Due to some contraints related to the EPRB phase camera, sharing the same DAC1955 board with the SPRB SBE control, only the 2 DAC1955 boards used for the SPRB LC controls and the SPRB Quadrant galvo loops have been updated.
- On the rtpc6, the Tolm output data flow was reduced from 12.6MB/s to 6.2MB/s
Operations performed between 2026-07-03-07h04m45-UTC and 2026-07-03-08h07m33-UTC
- all the loops were opened during the time of the operations
- and successfully closed at the end
Below the detailled list of the operations performed:
- Use DaqBox v17r11 for SPRB_dbox_bench and SPRB_dbox_rack server
- SPRB_LC and SRPB_Quadrants : 2 DAC1955 boards
- SPRB_DAC_LC_LVDT_in : DAC1955_SN008 - DBOX_SN005 - SPRB_dbox_bench : rtpc6 shared between the LC and Quadrant galvo loops
- SPRB_DAC_LC_LVDT_out : DAC1955_SN016 - DBOX_SN023 - SPRB_dbox_rack : rtpc6 used only for the LC loops
- the LC and the SBE loops were successfully closed after the upgrade
- We checks that the Tolm packect, related to the Quadrant galvo loop, was correctly received by the shared DAC1955 board (SN008)
