We noticed that the movements of the PMC piezo are correlated with the output power of the PMC. This correlation is due to an offset in the PMC lock signal, which keeps the the transmitted signal away from its maximum.
At 9:52 utc, we changed the offset in the ISYS_acl config file from -0.12 to -0.015 V. This set the central value of the PDH error signal to 0 V as wanted. However the PMC control loop brings the control loop signal to -22 mV instead of 0 V. So the correlation is still present after this intervention.
To correct the offset, we used the method descibed in gitlab. Instead of injecting a 270 Hz line, the injected signal is at 123 Hz (frequency written in the config file) with 0.05V amplitude.
By setting the offset level to -0.025 V, the 123 Hz line on PMC_tra was minimized. And the coherence at low frequency diminished.

We continued to deploy the DAC1955 v3r3 firmware on all the DAC1955 boards used at the NEB and WEB, execpt the ALS ones:
Operations performed between 2026-07-01-09h11m50-UTC and 2026-07-01-18h43m53-UTC
Below the detailled list of the DAC1955 boards updated and the related ACL's servers at WEB
Below the detailled list of the DAC1955 boards updated and the related ACL's servers at NEB
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:
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:
In the afternoon:
On June 16 morning:
In the afternoon:
On June 17 morning:
In the afternoon:
On June 18 morning:
In the early afternoon:
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.
Operations performed the 2026-06-31 between 2026-06-30-06h56m23-UTC and 2026-06-30-15h16m55-UTC
Below the detailled list of the DAC1955 boards updated and the related ACL's server
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
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 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.
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.
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)