Around 08:00 UTC, we started the intervention inside the WI tower (69190). Ettore was inside the tower, Cecilia and Ilaria was under the tower, while Luciano and Diana were at the WI base tower / TCS room.

At the beginning of the activity, the VPM process TCS_PAM_WI_PowerSupply was not working properly, and several signals related to PAM on DD remained grey, including the TX/TY motor positions and the actuator voltage/current signals. Giulio came to help recover the situation.

The WI viewport was reported to be in poor condition (69192).

As reference, we used the information from the previous PAM picomotors calibration performed on April 14th, 2026 (68992). 

Following the alignment security procedure prepared by Ilaria and Marco (69189), we switched on the red alignment laser and Ettore checked its position wrt the HR surface of the WI TM. After some alignment steps with the picomotors (Fig. 1), the actuator had been left at the following final motor positions:

• TX = -21555 steps, corresponding to approximately 3.9 cm downward

• TY = -4666 steps, corresponding to approximately 0.7 cm to the left

After the alignment, the red laser was switched OFF and the heater was powered, initially at 6 V and then increased up to about 7–7.5 V, corresponding to roughly 4–4.4 A. Ettore eventually managed to see the mask near the viewport (Fig. 2).

The actuator was finally switched off at 09:41 UTC, setting the voltage back to 0 V, and the activity ended.

The DaqBox server has been updated to be able to use the "zero" or "flat"(hold) extension policy for the DAC1955 channels . The DaBox v17r11 release implements this new facility.

This new release has been deployed on the SDB2 LC and SBE control loops and the related Acl 's server has been updated accordly (SDB2_LC and SDB2_SBE)

• operations performed between 2026-06-08-08h29m21-UTC and 2026-06-08-09h02m42-UTC 

The attached plots compares the SDB2's LVDT_in and LVDT_out channels for the following conditions

• purple: 2026-05-12-02h59m42s-UTC: DAC1955 firmware v2, DaqBox server v17r3p2, Acl linear extension policy, LVDT channels sent to the DAC1955 at 100KHz
• red: 2026-05-13-01h13m04s-UTC: DAC1955 firmware v3, DaqBox server v17r10, FPGA zero extension policy, LVDT channels sent to the DAC1955 at 10KHz
• blue: 2026-06-09-00h26m22s-UTC: DAC1955 firmware v3, DaqBox server v17r11,  FPGA flat extension policy, LVDT channels sent to the DAC1955 at 10KHz
• LVDT channels  ASD from 0Hz to 25KHz
• LVDT channels  ASD zoom around 10KHz
• LVDT channels ASD from 20Hz to 50Hz

The 2 next plots show the trend of the relevant channels over 2 days, from the  2026-06-07 to 2026-06-09,  for the SDB2 LC and SBE controls

Since the 2026-06-09-14h-UTC  the SBE_SDB2_ACT_F0H started to drift and now is saturating , as consequence the SDB SBE loops are opened  

This morning, before proceeding with the alignment of the WI Point Absorber Actuator (PAM) on the HR surface of the mirror, Ettore inspected the large ZnSe viewport (158 mm diameter).

Unfortunately, the viewport shows the same coating degradation already observed on the NI side (69077). 

The inspection of the small viewport will be carried out after the payload removal.

 Replacing the viewport will require the removal of the WI PAM actuator.

Nevertheless, we proceeded with the actuator alignment as planned (see dedicated entry). Before the viewport replacement, the actuator position will be recorded with respect to the alignment plate, so that it can be reinstalled in the same position afterwards.

Yesterday afternoon (June 8th), around 16h00 utc, I entered inside the detection lab to perform some checks in preparation of a future intervention on the SDB2 minitower (before I entered the lab, Davide Soldani increased the air flux at maximum speed in the detection clean room). During this intervention we would like to use a temporary camera on SDB2 to measure beam size. For this reason I checked the cabling of the EDB_B1t camera.

In particular I unplugged the camera green cable and remove it from the EDB cable tray in order to check if we could reach the SDB2 bench with such a cable, and the result is positive. After this check I reinstalled the green cable on the EDB cable tray and replugged it to the EDB_B1t camera. I also checked after while that the camera is still working.

I measured the needed cable length from the camera board #13 installed on the DAQ box #51 (under the EDB bench) up to the SDB2 minitower and estimated that we need a cable length of 6 m. To be noted that the power supply cable of EDB_B1t camera is 10 m long (according to the sticker attached  to the cable). The camera EDB_B1t model is Smartek GC1281XM-S90 (with large power supply connector).

During the inspection of the EDB bench, I noticed that there is cable plugged on the service mezzanine #10 (DAQ box 51) that is not plugged on the other side. This cable is reaching the extremity of the EDB bench (towards SDB2) and could be useful if one wanted to add a photodiode on the EDB bench to monitor the 1064 nm light reflected by the dichroic mirror located on the Hartmann Wavefront sensing beam path.

I profited from my presence in the detection lab to check the 2 inches optics stored in the rack. Here are the optics I could find : W208, W213, W216, W205, W203, W231, W232, V205, V206, V207. There is also an optics contained inside a package labelled W202 but I could not see the SN written on the optics itself. Additionnally, there is a beam splitter uncoated (R=8%), and there seems to be a commercial beam splitter R=90% (not the one we usually install on the detection benches) and there is a laseroptik box containing an optics with the label R=30%.

Some comments on the test involving the opening of the valves in the DET laboratory are reported below. The main actions performed during the test are summarized as follows:

• The AHU operating mode was changed from automatic to manual. In this configuration, the supply and return air fan speeds were fixed at values of 27.4 Hz and 13.8 Hz, respectively.
• All supply and return air distribution valves were switched from automatic mode, corresponding to the specific openings reported in Table of elog 68181, to a fixed opening of 5%.
• Additional tests were performed by varying the opening percentage only for the valves serving the Mini-Tower Area A (DET area), while the remaining valves were kept fixed at 5% opening and the fan frequencies were maintained at fixed values.
• At the end of the test, all valves and the AHU were restored to automatic operation.

Figures 1, 2, 3, 4 show zoomed views of the acoustic spectra measured by the microphone ENV_EDB_MIC during the transition from automatic operation to fixed fan frequencies and valve openings. The frequency ranges displayed are: Figure 1 (1–100 Hz), Figure 2 (100–400 Hz), Figure 3 (400–700 Hz), and Figure 4 (700–1000 Hz).

The colored curves correspond to three different operating configurations of the AHU system:

• black curve: supply and return fans, as well as all valves, operating in automatic mode.
• red curve: supply and return fan frequencies fixed at 27.4 Hz and 13.8 Hz, respectively, while all valves remained in automatic mode.
• blue curve: same fan configuration as the red curve, with all supply and return air distribution valves additionally set to a fixed opening of 5%.

Figures 5, 6, 7, 8 report the corresponding reduction factors with respect to the reference configuration (AHU operating in automatic mode).

Overall, fixing the supply and return fan frequencies does not significantly modify the acoustic spectrum, although a moderate reduction is observed in several frequency bands. A more pronounced effect is obtained when all supply and return air distribution valves are set to a fixed opening of 5%.
The ASD comparison shows a reduction of several broad acoustic structures, particularly below 400 Hz. This observation is confirmed by the reduction factor analysis, which reaches values between 2 and 5 over extended frequency regions. Above 400 Hz, the impact of the modified AHU configuration becomes less evident.
Moreover, the time-frequency maps of Figure 9 and 10, show the presence of several non-stationary spectral features above 300 Hz whose amplitude and frequency evolve throughout this part of the test. Consequently, the large reduction factors observed at specific frequencies are influenced by the temporal evolution of these spectral structures in addition to the changes introduced in the AHU operating configuration.
Overall, the results suggest that the reduction of the valve openings has an impact on the acoustic environment than fixing the fan frequencies alone, providing a measurable reduction of the acoustic noise level, particularly below 400 Hz.

**** Mini-tower A area (DET area) ****

Figures 11, 12, 13, 14 show zoomed views of the acoustic spectra in the same frequency ranges reported previously, measured while varying the opening of the MiniTower A return air valves (50%, 90%, and 5%) and keeping the supply air valves fixed at 5% opening. 
The acoustic spectra measured during the MiniTower A valve scan show that all tested manual configurations provide a reduction of the broadband acoustic noise with respect to the nominal automatic operation (black curve), particularly below 400 Hz. The configuration with the return valve set to 90% opening (blue curve) generally provides the lowest acoustic ASD over a large fraction of the investigated frequency range. In contrast, the configuration with the return valve set to 50% (yellow curve) introduces several additional narrow-band features above 400 Hz.
The time-frequency analysis (Figures 15, 16, 17) confirms that several spectral structures appearing above approximately 400 Hz are correlated with specific valve configurations and evolve following the changes introduced during the test.
Moreover, Figure 17 shows that the group of spectral lines observed in the 600–1k Hz region during the configuration with the return air valve set to 90% disappears approximately five minutes after switching the valve opening from 90% to 5% (10:15 UTC). 

Figures 18, 19, 20, 21 show the acoustic spectra measured during the last part of the test, where the return air valve opening was kept fixed at 5% and the supply air valve opening was varied between 50%, 90%, and 5%.
The comparison shows that the configuration with both supply and return air valves set to 5% (red curve) provides the lowest acoustic ASD over most of the investigated frequency range. This reduction is particularly visible between 100 and 400 Hz, where several broad structures observed in automatic mode and in the configurations with larger supply valve openings are significantly reduced. The same configuration also reduces the level of several spectral structures, especially in the 300–650 Hz region as shown in the spectrograms Figure 22, 23, 24.
In contrast, the configurations with the supply valve set to 50% (yellow curve) or 90% (blue curve) show higher acoustic levels and are often comparable to, or above, the automatic-mode reference.

An additional TF map (Figure 25) during the restoration of the MiniTower B valves to automatic operation (11:45 UTC) shows the reappearance of several narrow-band spectral features that had previously disappeared when both MiniTower A and MiniTower B valves were operated in manual mode. The temporal coincidence suggests that these structures may be associated with the airflow distribution of the MiniTower B branch. This behavior is particularly visible for the spectral features observed between approximately 300 Hz and 650 Hz.

**** Summary ****

Figures 26,27,28, 29 show the acoustic spectra for the nominal automatic operation (black curve), the configuration with all valves fixed at 5% opening (gray curve), and the two most favorable Mini-Tower A configurations identified during the test: supply valve at 5% with return valve at 90% (red curve), and supply valve at 5% with return valve at 5% (blue curve).

• The comparison shows that the nominal automatic operation is not the quietest configuration.
• The configuration with all valves fixed at 5% opening also provides a reduction in some bands, but it introduces additional narrow-band structures, especially above 400 Hz. This suggests that forcing all valves to the same low opening is not necessarily the optimal acoustic configuration.
• Among the tested configurations, the most favorable ones are those with the Mini-Tower A supply valve fixed at 5%, namely supply 5% / return 90% and supply 5% / return 5%. However, the nominally identical 5% / 5% configuration obtained during the return-valve scan (return fixed at 5% and supply varied) resulted in lower acoustic levels than the 5% / 5% configuration obtained during the supply-valve scan (supply fixed at 5% and return varied). This indicates that the acoustic response may depend not only on the final valve openings, but also on the sequence of valve adjustments and/or on the airflow stabilization time.

The results suggest that an optimized valve configuration could reduce the acoustic noise in the DET area with respect to the nominal automatic operation. Further dedicated tests are required to verify the reproducibility of the most promising configurations and to assess their long-term impact on the stability of the clean-room environmental parameters.

Tomorrow (June 9), we plan to access the NI tower to perform preliminary measurements and instrumentation checks in preparation for the mechanical transfer function measurement of the instrumented baffle. 
The activity is subject to final confirmation.

Today around 15h10 UTC (after having checked that the gate valve between NE and NI is closed and without any window; for people working on the NI tower), the NE Pcal laser has been switched on to 1.3 W (figure 1). The Rx sphere is still absent and will be installed tomorrow morning.

The relative calibration of the Tx_PD1 and Tx_PD2 photodiodes seems to have changed by about 0.5% since the last time the Pcal was on, in December 2025 (see figure 2). This is not related to a change in the offset (see figure 3).

To measure the frequnecy response of the plant of the BPL, a broad band noise (up to 500 Hz) has been injected on the piezo signal, after the driving matrix. The amplitude of the noise was 0.1 V, each injection lasted at least 3 min. the injection times were:

• EIB_M1BH -> 13:23:00
• EIB_M1BV -> 13:28:00
• LB_M14H -> 13:32:00
• LB_M14V -> 13:38:00

The frequency response from the injected noise to the piezo response was computed. On every piezo, a pole around 3.0 +/-0.1 Hz was measured, and on every quadrants, a zero at 1.0 +/- 0.1 Hz, and a pole at 11.0 +/- 0.3 Hz.

To compensate for the  measured plant frequency response, a QPD_flatten filter was added after the normalized quadrant signals, and PZT_flatten filter was added after the driving matrix before the piezos. The DC gain of both filter is 1.

The parameters of the filters are:

ACL_FILTER_SET     "BPL_PZT_flatten"    1     1    0.01    20
ACL_FILTER_ZEROS   "BPL_PZT_flatten"      3      0
ACL_FILTER_POLES   "BPL_PZT_flatten"      500    0

ACL_FILTER_SET     "BPL_QPD_flatten"    1     1    0.01    20
ACL_FILTER_POLES   "BPL_QPD_flatten"    1     0
ACL_FILTER_ZEROS   "BPL_QPD_flatten"    11     0

All the control filters have been replaced by a simple integrator with a 2nd order pole at 200 Hz.

ACL_FILTER_SET        "BPL_tiltx_flt"        1             -50     1     20    
ACL_FILTER_POLES    "BPL_tiltx_flt"        0            0
ACL_FILTER_POLES    "BPL_tiltx_flt"        200            0.707

The loop can close with the filter. The frequency response must be measured again to make sure that the new plant response is flat.

The noise measured  on the QPD signal is lower than before.

The HWS-DET SLED has been switched off at 13:32 UTC.

A question is how stable are states of CARM offset reduction over long times (~1h), in case this could be used for measuring the input mirror absorption instead of using CARM NULL 1F as the state from which to unlock from.

Figure 1 and 2 shows the statistics for step 2 (index=90) and step 3 (index=95) for 6 months from Sep 1 2023 to Mar 1 2024. The 6-month of commissioning when the input power was reduced from 25W to 12W, and then increased in two steps to 17W before the start of IR1. In blue are the "successful" steps, in the sense that the next step of the lock acquisition is a higher index, and in red are the "failed" steps, in the sense that the next step has a lower index (unlocked).

During that period most step 2 and step 3 transition were successful, and a few of the step 3 states had a duration of a few thousands seconds. This shows that it is possible to stay in step 3 long enough to have a useful input mirror absorption measurement. However, it doesn't show if that can be done reliably and repeatebly. The two cases of the interferometer remaining for long time in step 3 are on Oct 29 and on Nov 20.

Figure 3 and 4 show the same but for the period of 18 months from Sep 1 2022 to Mar 1 2024. So includes a lot of the time when we had trouble locking the interferometer. In this case there is many more failed steps, but still in each duration bin there is more successful than failed steps. There hasn't been more attempts of staying in one of those states for a few thousands seconds, so it doesn't add more information on the long term stability of those states.

/users/mwas/ISC/TCStuning_trend_20260222/longTermTrendIndex.m

SWEB_50Hz server crash 

The SWEB_50Hz server,  used to extend the frame dt from 0.2s to 1s and to build the online 50Hz channels for the  channels related to this tag  "V1:SWEB* V1:SBE_SWEB_* V1:Sa_WE* V1:SA_WE*  V1:FCEB_*  V1:FCEM_* V1:SBE_FCEM_* ", crashed yesterday morning  at 2026-06-07-09h19m53-UTC .

It has been restarted only this morning at 2026-06-08-06h22m00-UTC .

As consequence the channels related to this tag "V1:SWEB* V1:SBE_SWEB_* V1:Sa_WE* V1:SA_WE*  V1:FCEB_*  V1:FCEM_* V1:SBE_FCEM_* " are missing for all the streams (raw, raw_full, rds, trend and trend100s) from 2026-06-07-09h19m53-UTC to 2026-06-08-06h22m00-UTC 

Trend100s for 2022,2023 and 2024

On request of the commissioning team, the trend100s data have been computed using the trend ones for the following years; 2022, 2023 and 2024.

The FbTrend100s server configuration has been updated to use the full disk space available , operation performed the 2026-06-05-12h56m05-UTC

On Friday afternoon, we tried to rebalance EIB by moving some of the counterweight on the top of it. We also tried to remove/attenuate some of the mechanical shortcuts still present (mainly water pipes and RF-QPD cables).

At the end, we managed to obtain a quite good position for all the DoF but the Z one. Anyway, we could close the loop in the nominal position, with a couple of actuators with high correction.We kept the beam blocked on the laser bench for the weekend.

From a message received from our external collaborator Renato Romero:

Friday June 5th at 17:30 UTC the 1 Hz comb disturbance stopped completely: Figure 1

Interestingly, in the subsequent minutes are again well visible the disturbances that we attribute to trains: Figure 2

The problem of the PDU server was that the TANGO PDU server was also up and running and was interfering with the current server. Tango instance has been stopped, problem resolved.

ITF DOWN in UPGRADING mode.

Palnned activities:

• WI controls opened from remote by Boschi (13:15 UTC)
• WI venting (started at 13:30UTC)
• BPL Commissioning (in progress...)
• TCS Chiller assembly & test (in progress...)
• NI PAY assembly concluded (L. Naticchioni, E. Benedetti, H. Vocca, F. Travasso, A. Piluso, M. Montani, F. Piergiovanni)
• 13:12 UTC - PduServer process restarted via VPM following the procedure descripted in the entry.

This morning at around 1AM UTC the external magnetometer detected a decrease (but not disappearence) of the comb noise intensity.

We investigated further the 1Hz comb noise, which is still present.

Last Friday (May 29) we performed some measurements with one Bartington 3D Magnetometer and the portable spectrum analyzer CoCo80x.

First we found that the noise was present and quite intense close to the vacuum pipe of the W arm. Figure 1 shows the probe position in the first measurement: its tip was approximately 1 cm from the chamber at 900W and so approximately 0.6m from the tube center, the X axis was oriented along the tube, Y was vertical and Z was radial to the tube. In this position, the 1Hz comb field is oriented mainly along Y, being consistent with the field radiated by a current flowing along the tube. This is shown in Figure 2. The intensity is similar to what measured by similar sensors positioned close to vac chambers in CEB: that is a few nT/sqrt for the 1 Hz peak - compare with Figure 3 which uses the same 20s fft window.

The same Figure 2 shows recordings when the same probe was positioned by doubling the distance from the tube center: the field orientation is as well along Y and the intensity approximately halves. This looks consistent with a field being emitted by the beam tube. We then positioned the probe on the tunnel floor (which is the 3rd plot in Figure 2): the intensity is rougly the came but now the B field vector is oriented at 45 deg in the plane perpendicular to the tube, which also looks consistent with a field emitted by the tube.  Yet, when positioning the probe close to the tunnel roof a large signal is noticed (Figure 4). No measured amplification at the ethernet switch box and cables running along the tunnel wall.

We then repeated the measurement close to the tube at 1800W and 2700W: the emitted comb is there with similar intensity and orientation characteristics (Figure 5). This seems to contraddict the hypothesis that the noisy current is generated in CEB and decays flowing outwards along the tubes. While at 1800W we also sniffed the vacuum pump station as well as cables but found no amplification. At 2700W we also took again a measurement close to the tunnel roof, this time being outside. Interestingly the noise disappeared from the probe when positioning the probe in the middle of the nearby road (green track in Figure 5).

We finally took some measurements in the central external area: Figure 6. The comb is present! The signal is particularly intense close to the methan gas pipe tube nearby the guardiania. Il looks that one such pipe runs inside the EGO site along the South fence. We also moved in the external road and towards the location (approx. 100m before the EGO gate) where the SNAM company performed heavy works between February 5th untill the first week of April (Thank you Maria fro recording the dates). The noise level is more or less the same when moving the probe on a tripod at 1.5m above the ground (Figure 6).

Our suspect is that the source of the noise might be related to galvanic anticorrosion currents in the methan pipes, which in the past produced a non stationary 5Hz comb: https://logbook.virgo-gw.eu/virgo/?r=55542. This time instead the noise  is very stationary: the comb is extremely narrow and consistent with a GPS synch device.

A more stringent proof could come from measuring a few km away from EGO, in the locations explored in the past.