On Tuesday morning we completed the realignment of the BPC loop. We started by zeroing the corrections sent to the actuators and centering the DC offset on the amplifier, in order to maximise the actuator dynamics.

With the PMC locked and the BPC loop closed, we used the M6 and M8 mirrors on EIB to center the BPC QPDs. The loop closed easily in full bandwidth, with less than 1V of correction per DoF. The power measured at the output of EIB_M9 was around 29W, similar to what we measured before the April intervention.

We then closed the BCP at the usual setpoints, and coarsely realigne MC and SIB1 in order to relock the IMC. Despite the presence of peaks above 8-10W (the power threshold for the rampauto) we didn't succeed in relocking.

We found a phase shift of almost 45° on the demodulated error signal, most probably due to the swap of the 22 MHz EOM with its spare. The new value for the phase is 2.85. A finer tuning will likely be performed once the IMC recovery is complete.

Today, the OLTF of the IMC under these new conditions was measured (see Fig. 1), showing an UGF of less than 90 kHz and ~23° of phase margin, significantly lower than the last measurement at the end of April.  This may be a direct consequence of the chiller and the slave laser issue from early May, with the SL not being properly seeded by the ML beam. For the time being, we will not work on improving the SL loop.

With the IMC locked, we checked the IMC working point (new value: −0.85), realigned the IMC cavity, and measured the new AA sensing matrix and angular galvo offsets. The AA has been closed in full bandwidth. Moreover, the RFC locked directly after closing the IMC AA.

Some remarks, though:

• The longitudinal working point is smaller with respect to the last measurement.
• The AA error signals show quite large offsets across all channels.
• The IBz loop, which links BPC_X to the Z position of the SIB1 bench when the IMC is locked, is currently not working. The BPC X DoF, however, works correctly when using the BPC QPD error signal. For the time being, we have manually adjusted the X setpoint to minimise the IBz signal. We will investigate further to identify the origin of the problem.

This morning, we tested a Güralp 3ESPC seismometer at the North end building. The sensor has been purchased for the deployment of the external environmental monitoring stations.

The Güralp 3ESPC was temporarily connected in place of the NEB reference Güralp seismometer and installed close to the electronics racks, Figure 1.
A dedicated interface device was developed to lock, unlock, and center the sensor masses, Figure 2. During the test, the masses were first unlocked to verify the correct operation of the instrument and were then locked again using the same interface.

Figure 3 compares the spectra measured by the tested seismometer (blue curve, ENV*SEIS_*) and by another Güralp seismometer (orange curve, ENV*SEIS*T*) installed close to the tiltmeter. The two sensors show a very good agreement at low frequencies, with high coherence below approximately 5-10 Hz. At higher frequencies, the tested sensor exhibits a slightly higher noise level, most likely because it was temporarily installed close to the electronics racks. 

Overall, the test confirms the correct operation of the seismometer.

The change in SDB1 TX and TY set point is understandable. After the update the set points are exactly as written in the configuration file. Before the update the set points were most likely still the floating set points that are corresponding to where the beam actually was before the interferometer beam was disable a few months ago. A drift of a few urad is usual between the static set point and the floating set points.

ITF DOWN in UPGRADING mode.

Activities communicated to the control room:

• NI and WI instrumented baffles checks (Ballester, Gargiulo, Gherardini, Pasqualetti)
• MC cavity lock (De Rossi, Gosselin, Lagabbe, Spinicelli)
• Seismometer test at NE (Gherardini, Fiori, Tringali)
• DAC1955 v3 firmware deployment on rtpc8/9 (SWEB) (Masserot)
• NI Payload preparation (Vocca, Travasso)

From Monday June 15 to Thursday June 18, we worked in the installation of new instrumented baffles and the replacement of the existing BafFlanges in the NI and WI towers. In all tasks in the tower, the IFAE team was assisted by Julien Gargiula, Nicola Menzione, Cecilia Zaza. Feedthrough and internal cabling were installed by Fabio Gherardini.

On June 15 morning we proceeded to several tasks in parallel:

• Install drawers in NI rack #2, unit 32 (David). (image 1)
• Assemble white boxes (Otger). (image 2)
• Cleaning of the big structure, installation bars and several small pieces (Alex and Lluïsa-M. with the guidance of Nicola and Cecilia). (image 3)
• Add PT100 and "clips" to baffles preassembled on May 4/5. (Noel, Jose & Pepe).
• Run electronic tests (again): all OK, but one cable found faulty (David, Pepe), taken to Vincenzo for repair (Lluïsa-M.).
• Replace crooked antenna (Pepe).
• Disassemble NI BafFlange (Noel & Jose).
• Prepare everything for the afternoon installation in the tower (Alex, Noel & Jose).

In the afternoon:

• Move equipment to NI rack (David & Otger).
• Move the instrumented baffle to NI tower. (images 4 and 5)
• Installation finished by 5 pm (Noel, Jose & Alex). The baffle is measured to be at 10 mm (uncertainty of +- 1 mm) from the flange with a deviation from the vertical plane of +- 0.1°. (image 6)
• Equipment moved to NI (Pepe, David and Otger).

On June 16 morning:

• Install the cable connecting the midpoint to the feedthrough (Fabio).
• Otger and David read the first data. Everything looks OK.
• Alex, Noel, Maria & Piernicola measure the transfer function (TF) with accelerometers. (images 7 and 8)
• In parallel Jose and Pepe assemble the second baffle. (image 9)
• In parallel Otger and David discuss computing requirements with Erin Seder.

In the afternoon:

• Once we get the OK from Maria regarding the TF data, the new BafFlange is installed in the NI tower (Noel, Jose and Alex). (image 10)
• In parallel Alex and David check electrical connections of the second baffle in the clean room.
• Install external cabling of the WI (Pepe).

On June 17 morning:

• Nicola and Cecilia clean the WI tower.
• Once finished, Alex, Noel and Jose disassemble the WI BafFlange and install the second instrumented baffle. The baffle is measured to be at 10 mm (uncertainty of +- 1 mm) from the flange with a deviation from the vertical plane of +- 0.1°. (image 11)
• Pepe and David check that power is reaching the baffle properly.
• Otger and David start readout tests.

In the afternoon:

• Struggling with WI baffle readout, half baffle does not produce signal. Problem due to external cable, fixed. Everything is OK now. Install WI inner tube and back baffle.

On June 18 morning:

• (Noel, Alex and Piernicola) TF measurements of the WI baffle. (image 12)
• Once we get the OK from Piernicola regarding the TF data, the new BafFlange is installed in the WI tower (Noel, Jose and Alex). (images 13 and 14)
• Installation in the towers finished. (images 15 and 16)

In the early afternoon:

• Experiencing problems to set up the WI system, requiring several attempts to get it. Once connection is obtained there are no data lost and data make sense. External cables checked and found OK. Will request checking the cable connecting the midpoint to the feedthrough and continue the debugging remotely.

 
The problems disappeared after replacement of the mid connector. See entries  https://logbook.virgo-gw.eu/virgo/?r=69271 and https://logbook.virgo-gw.eu/virgo/?r=69276.

We deployed the DAC1955 v3r3 firmware on almost all the DAC1955 boards used for the SDB1, SDB2 et EDB systems.

• rtpc13 : the 2 DAC1955 boards are updated
  • Tolm output data flow reduced from 4.2MB/s to  0.42MB/s
• rtpc1   : 9 DAC1955 boards over the 13  are updated  
  • it remains the 2 related to the SQZ and the  2 driven by the EDB server
  • Tolm output data flow reduced from 54.5MB/s  to 20.6MB/s 

Operations performed the 2026-06-31  between 2026-06-30-06h56m23-UTC and 2026-06-30-15h16m55-UTC

• all the loops were opened during the time of the operations
• and successfully closed at the end

Below the detailled list of the DAC1955 boards updated and the related ACL's server

• SDB2_LC  and SDB2_SBE were already done for the 3 DAC1955 used
  • SDB2_DAC_LC_LVDT_out : DAC1955_SN019 - DBOX_SN028 - SDB_EDB_dbox_rack    : rtpc1 
  • SDB2_DAC_LC_LVDT_in   : DAC1955_SN069 - DBOX_SN106 - SDB2_dbox_bench        : rtpc13
  • SDB2_DAC_SBE0              : DAC1955_SN022 - DBOX_SN027 - SDB_EDB_dbox_rack    : rtpc1
  • loops successfully closed  
• EDB_PC (Phase Camera)  : 1 DAC1955
  •  SDB2_DAC_EDB0             :  DAC1955_SN023 - DBOX_SN027 - SDB_EDB_dbox_rack    : rtpc1
  • plot showing the DAC1955 input channels and the Phase camera related outputs
• SDB1_FI : 1 DAC1955
  • SDB1_DAC                        : DAC1955_SN042 - DBOX_SN016 - SDB_EDB_dbox_rack     : rtpc1
  • we checks that the Tolm packect is correctly received by the DAC board
• SDB2_Quadrants : 1 DAC1955
  • SDB2_DAC_galvo              : DAC1955_SN101 - DBOX_SN105 - SDB2_dbox_bench         : rtpc13
  • we checks that the Tolm packect is correctly received by the DAC board: It remains to check that the galvo loops are correctly running
• SDB1_OMC, SDB1_Quadrants and SDB1_FAST_SHUTTER : 1 DAC1955
  • SDB1_DAC_OMC_B5        : DAC1955_SN021 - DBOX_SN030 - SDB_EDB_dbox_rack     : rtpc1
  • plot showing  the successfull OMC temperature stabilization and the presence of the PZT modulation line
  • we checks the B5 quadrant VBias are OK 
  • It remains to check the FAST_SHUTTER is correctly running 
• SDB1_LC :  3 DAC1955
  • SDB1_DAC_LC_LVDT_out  : DAC1955_SN012 - DBOX_SN028 - SDB_EDB_dbox_rack     : rtpc1
  • SDB1_DAC_LC_LVDT_in    : DAC1955_SN025 - DBOX_SN016 - SDB_EDB_dbox_rack     : rtpc1
  • SDB1_DAC_MAR                 : DAC1955_SN048 - DBOX_SN030 - SDB_EDB_dbox_rack     : rtpc1 
  •  the loops were successfully closed but the TX and TY set points have a little bit shifted, the experts must check
• the EDB_DAC2 board installed bu not yet used has been updated too
  • EDB_DAC2                           : DAC1955_SN055 -  DBOX_SN113 - SDB_EDB_dbox_rack     : rtpc1

During the operations, we updated by msitake the firmware of one mezzanine(id 3) of a DBOX (SN23) used for the SPRL local control : we restored the correct firmware and after the SPRB LC were successfully closed  too  

ITF found in DOWN State and UPGRADING Mode.
All times are UTC.
07:35 DAC1955 on rtpc1 firmware update (Masserot). 
08:00 - 10:14 INJ LAB activity (Spinicelli, Lagabbe).
09:24 INJ LAB AHU set to portata nominale (Operator).
10:16 INJ LAB AHU set back to portata ridotta (Operator).
14:17 Travasso, Vocca, and Benedetti ended the activity on the payload scheduled for today.

We first realigned the beam manually on the BPC QPDs and brought it back to its nominal setpoints. We then worked on the EIB balancing and successfully closed the loop.

From the control room, we attempted to lock the BPC, but the loop would not close. Investigations revealed that only one of the PZTs was actually responding. Further checks showed that some of the LEMO connectors on the box used to add the output resistance required for the low-pass filter had been damaged during resistance measurements performed a few weeks ago. Roberto repaired it, and all four PZTs are now responding normally.

However, the manual alignment performed in the morning had been carried out with incorrect PZT settings, leaving the beam significantly displaced from its nominal position. We will need to return to the laser lab tomorrow to repeat the manual alignment.

We also worked on the alignment of the IMC cavity. We managed to obtain flashes up to 5–6 W, but we have not yet relocked the cavity. This work will continue once the BPC loop is closed.

For the night, the PMC was left scanning (with a 1.5 V offset applied to its error signal), and the mirror at its output was flipped.

Work will resume tomorrow.

ITF DOWN in UPGRADING mode.

Activities communicated to the control room:
- 06:30 UTC Control Building air ducts (Soldani)  In progress...
- 09:00 UTC - IMC relock preparation (Gosselin, Spinicelli, Lagabbe).  ACS set in portata nominale.
- 11:45 UTC - IMC relock (Gosselin, Spinicelli, Lagabbe).  ACS set again in portata ridotta.
- 09:00 UTC - Fallen mirror anchors debonding (Vocca, Travasso). In progress...

After the daily meeting I went in the central building to place some laser safety labels on the taped viewports of SIB1 PR and SPRB towers, 
To be noted that since last week the viewport of SPRB used to extract the B4 phase camera beam has been tapped (first picture). 

ITF found DOWN in UPGRADING mode

Activities communicated to the control room:

Laser safety panels placed on SIB1 tower, PR tower, SPRB tower (Gosselin)
TCS auxiliary lasers cooling system  - work in progress (Ciardelli, Menzione)
LLab door troubleshooting - repair in progress (Marano)

We measured again the powers:

- at the input of the EOMs --> 43 W 09:27:45 (PMC TRA 0.53 V)

- after the 3 EOMs --> 41.6 W at 09:17:30 UTC (PMC TRA 0.53 V) --> 3% losses

- after M5 -- > 36.05 W at 09:51:25 UTC --> 16% losses

Optimization of the transmitted power

• tuning of the half waveplate at the input of the EOMs to maximize the power after M5--> we increased from 36.05 W to 37.45 W after M5
• tried to maximize again the power transmitted by IPC 1 --> no improvement
• small movements with BPL to see if we improve the transmission with the beam alignment in the EOMs --> with setpoints xset = -430 and the others to 0 we obtained 42.5 W after the EOMs at 12:21:45 (0.535 PMC TRA)
• zeroing of the corrections on PZT of LB M14 mirror (we moved the screw with loop closed to reduce the corrections of INJ BPL PZT LB M14H/V CORR) and recentering of the near field QPD to set the shift X from -300 to 0 (loop open and DC on we moved the h screw of the mirror just before BPL QN to bring INJ BPL X ERR from -300 to 0, and then changed the setpoint to 0 in the cfg file). Now all the setpoints are 0 and the corrections have been reduced to <1 V

We remeasured the input power and the power after the 3 EOMs getting 42.4/43.1 --> 2% losses in the 3 EOMs

power after M5 37.8 W --> 13% losses in the line EOMs + IPC + Faraday isolator

Since the biggest part of the losses occurr in the line IPC +Faraday we proceeded then measuring the power after M5 and better aligning the beam with the mirror just before the IPC. We also inspected the optics with a dentist's mirror and nothing strange was noticed

We got 39.3 W after M5. 39.3/43.1  (a second measurement of the power gave 38.3 W after M5, since it is slightly dependent on the beam impinging point on the calorimeter) --> 9-11% losses in the line EOMs + IPC + Faraday isolator

Characterization of the beam after M5 (to be compared with the last measurement done on the 4th of May 2026 #69064). 

Beam profiler used: DataRay, power 4mW after M5 (reduced with IPC1) + filter OD 7, light in the LL switched off

545 um (instead of 508 um on the 4th of May, to be checked the PMC TRA value) at z= -0.54 for M5

Realignment and calibration of EIB POUTto be checked

Set IPC1 back as before at 30W

nb: for the high power measurements we used the ophir calorimeter (avg 10s) with a diverging lens -30 mm in front of it (we do not have the serial number of the lens, maybe it is custom, but it seems to have an AR coating)

ITF found DOWN in UPGRADING mode with several loops opened due to the earthquake occurred in Venezuela (Mag 7.5).

planned activities communicated to the control room:
- TCS chiller at 1500W - 07:00 UTC - in progress... (Ciardelli, Zaza)
- EOM contamination checks - 08:00 UTC - in progress... (De Rossi, Lagabbe, Spinicelli)
- Ethernet cable installation from TCS room  to CEB hall - 12:00 - 13:00 UTC - (Vacuum team)

Air Conditioning
In order to allow the activity in Laser Lab, at 08:00 UTC, I set UTA INJ in Portata Nominale, following the new procedure.

SBE
Benches loops recovered after the earthquake:
SDB1_ID, SIB2, SPRB_SBE, SWEB_SBE, SNEB_SBE, SDB2_SBE.
For SDB2 and SNEB I had also to recover the vertical positions via stepping motors.

SUSP
Suspensions loops recovered after the earthquake:
NE (ID and LC), WE (ID and LC), SR (ID and LC),

SUSP
(25-06-2026 07:00 - 25-06-2026 08:30) From remote
Status: Ended
Description: At 07:00 UTC I tried to close MC loops but the signals in all dof diverged, so I re-opened it and contacted Susp expert who fixed the problem.

To measure the losses in the chain containing the EOMs, the Faraday and the IPC1 on EIB, the power was measured with a calorimeter, preceded by a f=-50mm devergent lens (newport KBC043)

• Before the EOMs, the measured power was 32.6 W at 12:58:30 UTC.
• After the EIB_M5 mirror, the power was 24.0 W at 14:01:00 UTC

We tried to measure the power without the divergent lens,

• Before the EOMs, P=42.1 W at 14:13:50 UTC
• After EIB_M5, P=30.5 W at 13:02:45 UTC

In every measurements, the output voltage of the PMC_TRA photodiode was stable around 0.53 V. The BPL was closed. It appears that the presence of the lens changes the measurement by 25%, probably due to an absorption or an uncoaded surface or the variation of the beam size on the calorimeter. So we decided to use another lens f=-30mm. 

• Before the EOMs: P= 42.8 W at ???
• After EIB_M5 P=30.1 W at 14:31:40 UTC

The estimated losses of the whole chain is 30%.

We recentered the beam on the BPL quadrant, with the PMC cavity locked, we closed and open the BPL loop, so the piezos are roughly at the position that send the beam into the EOM. Then we move the QN quadrant vertically until the Y signal is cancelled, and the QF until TX signal is cancelled. Then all the setpoints of the BPL are set to 0 urad and 0 um.

After that,we tried to rotate IPC1 while measuring the power after EIB_M5 in order to maximize the measured power. We managed to reach a power of 34.6 W, which corresponds to a 20% loss. Then we changed the horizontal shift setpoint (X_SET signal) in order to maximize the power measured by the calorimeter. By seting X_SET to -200 um, we reaached a 35.6 W power. Which correspond to a 16 % power loss. The others degrees of freedom remains untouched. 

Below the list of the activities communicated in control room:

- INJ: EOM contamination test;

Air Conditioning
from 12:40UTC to 15:40UTC I set the injection area air conditioning system in "Portata Nominale" to allow the work on EOM.

SBE
recovery of SWEB vertical correction with F1 step motors from 7:30UTC to 7:40UTC.