This morning we performed spot magnetic measurements in the area where the new environmental monitoring stations will be installed. Excavation works in this area are scheduled to start after the Easter break.

Measurements were carried out by placing the magnetic probe approximately at the center of the area and then repositioning it to different locations at a distance of about 8 m from the center within the marked perimeter, Figure 1. The magnetic field was measured using a Bartington Mag-03MC100 sensor (range ±100 μT, calibration factor 100 mV/μT), connected to a portable data logger. The probe was consistently oriented with its z-axis (ch-3) pointing towards North during the campaign. For each position, spectral measurements were acquired and stored.

During the measurements performed at WEB and CEB, we observed the presence of a noise source, switching on and off in a non-regular manner.

This behaviour was identified through the magnetic spectra: when the source was not active, only the X-axis (ch1-x) showed a significant reduction of the noise floor, reaching values of a few pT/√Hz for frequencies above ~90–200 Hz. The Y and Z axes did not show any noticeable variation and remained unchanged regardless of the source activity, Figure 2.

The fact that this feature was not observed in the North position could be related to the source being continuously active during that specific measurement. 

It is worth mentioning that agricultural activities were ongoing in the vicinity of the site during all the measurements.

In addition, distinct spectral features are observed around ~23 Hz and ~32 Hz, consistently present in all the acquired measurements, Figure 3.

Below, we report the spectral amplitudes of the main power-related lines at 50 Hz and its harmonics (150 Hz and 250 Hz). The values have been converted into magnetic field units using the sensor calibration factor, corresponding to 1 μV = 0.01 nT. 
For some positions, measurements were taken both when the magnetic noise source was active and when it was inactive, since its disappearance was noted during data acquisition, thus allowing both conditions to be recorded. In addition, dedicated measurements were performed by placing the probe in proximity to the external magnetometers.

***************** NEB ************************************

********************* WEB**************************

************************ CEB **************************************

***************External magnetometers*****************

In line with the planning detailed here:

https://indico.igwn.org/event/7/

Today we proceeded with the 2nd Computing core services shutdown starting at 12:00 and with UPS electrical shutdown in the Control Building lasting one hour starting around 13:00.

The new UPS serving the Computing Room has been put in operation and Computing core services has been progressively restored during the afternoon and made available around 18:00.

To proceed quickly with some test of the authentication chain the Cm and VPM hosting machines (olserver111 and olserver113) has heen restarted and the Cm servers for Cascina, CascinaLV, CascinaTest, CascinaLVTest (and their corresponding VPM servers) have been restarted without problems.

The rest of detector computing and storage services are being restarted with the goal to be ready early tomorrow morning to resume the DAQ chain possibly until making operative the Detector Monitoring System.

On Monday, March 30, we transported the WI PA actuator from Rome Tor Vergata to the site. Thanks to Fabrizio, we unloaded the actuator at the entrance of the Central Building, leaving it there until the following day before moving it to the TCS room.
During the maintenance day on Tuesday, March 31, we mounted the lifting frame used to sling the actuator to the overhead crane (Fig. 1). Fabio then helped us operate the crane and move the actuator toward the TCS room (see Fig. 2).
We placed the actuator on a trolley and moved it inside the TCS room. There, we installed the heater source and its paraboloid inside the actuator structure (Fig. 3), then left it in the TCS room properly covered with plastic film (Fig. 4).

The ITF was found in DOWN and UPGRADING mode with the controlled shutdown in progress.

All subsystems were placed in a safe state by their respective experts, and the DAQ was shut down at approximately 16:00 UTC.

All the DAQ servers have been stopped . Operation complete at 15h41m-UTC 

Note:  the DaqBox server running configurations stored in ~virgorun/.local/share/DaqBox have been moved in the ~virgorun/.local/share/DaqBox/20260325-ComputingShutdown directory to ensure the full reconfiguration of these DaqBoxes at the recovery time 

We completed the Acl v1r39p17 version deployment 

• SQZ rtpcs: rtpc2 (trend plot), rtpc3 (trend plot) and rtpc23  (trend plot)
  • All the LC and SBE loops were already openned by Marco between the  2026-03-23-23h58m42-UTC and 2026-03-23-23h59m27-UTC
  • Operations performed between 2026-03-24-07h11m30-UTC and 2026-03-24-07h22m09-UTC
• INJ rtpc: rtpc19 (trend plot)
  • The EIB bench has been blocked by Matthieu around 7h10-UTC
  • Operations performed between 2026-03-24-07h22m46-UTC and 2026-03-24-07h26m43-UTC

The Acl update on the SUSP rtpc(rtpc4) has been postponed after the computing shutdown, in agreement with the TCS and commissioning coordinators

ITF Found in LOW_NOISE_3_ALIGNED State and COMMISSIONING Mode.
All times are UTC.
07:00 ITF manually in DOWN state to start the powering off of the ITF for the upcoming controlled shutdown.
07:13 Earthquake in Fosdinovo (MS), ML 4.0 (INGV);
08:27 Set PAUSE to nodes: ITF_LOCK (Operator), SQZ_FLT (Operator), and DET_MAIN  (Gouaty);
08:32 Opened position loops via VPM of: SIB2_SBE, SDB2_SBE, SNEB_SBE, SWEB_SBE, since they opened themself between 7:44 and 7:50 maybe related to the Earthquake in Fosdinovo (MS);
08:44 UPGRADING Mode set;
08:52 INJ OFF (INJ PMC FLIP set to "UP") (Gosselin);
8:55 - 09:03 TCS Lasers all off (Melo) and Chillers Guardian system off (Ballardin), see entry #68947; 
09:10 - 10:38 Shelved TCS Flags in DMS: mean_TCS_NI_CO2_PWRLAS_10, mean_TCS_WI_CO2_PWRLAS_10, mean_TCS__GUA_WI_FLOW_10, mean_TCS__GUA_NI_FLOW_10, mean_TCS__GUA_BCK_FLOW_10, TCS__GUA_Rules, mean_TCS__GUA_BCK_TE_10, mean_TCS__GUA_NI_TE_10, and and mean_TCS__GUA_WI_TE_10 up to 07-04-2026 09:00 UTC (Operator under request of Nardecchia);
09:46 NI/WI Etalon loops open (Operator);
09:54 Opened SBE_EIB position loops: PID and Actuation (Operator);
09:58 Set PAUSE to nodes: OMC_LOCK, and ITF_CONDITIONS (Operator);
10:29 - 10:37 Automation Metatron nodes VPM process turned off (Bersanetti);
The larger part of the VPM processes has been shutted down during the morning and the afternoon;
ITF left in DOWN State and UPGRADING Mode;

Relevant logbook entries reporting switchoff sequences:
- TCS actuators in CB switched OFF (#68947, and #68947);

WE RH  and NE RH have been turned off at 14.28 UTC and 14.29 UTC, respectively.

Immediately after it the related processes on the VPM have been stopped as well. 

Switch-off sequence:

• 08:22 UTC – SR RH OFF
• 08:24 UTC – PR CHRoCC OFF (7200 s ramp)
• 09:00–09:02 UTC – CO₂ CH lasers OFF
• 09:02–09:03 UTC – CO₂ main laser OFF
• 09:03 UTC – Guardian system disabled and CO₂ chiller OFF

Note: outputs disabled; power supplies left ON.

We checked that the loops were working well after the ACL update.

We sent SQZ_MAIN SQZ_LOCKED_NO_FC and it went at the first attempr

We then aligned the filter cavity but we had to modify some of the code lines in the FC Alignment interface.

We locked the FC both with only the mirror and also with the laser. We updated the gains. SQZ_CC GAIN=4 and LFC_Z_GAIN = 6 instead SQZ_CC GAIN=1.55 and LFC_Z_GAIN = 6

We also run a SQZ CC Phase can with SR tuned at 17:34 UTC CC GAIN 40000. We also noticed that the CC sensing noise is dominant above 100 Hz

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Once the detuning of SR started we open the shutter, we set 4.1 rad of SQZ angle and we run autoalignment loop for more than one hour. Then we did the following measurement:

• 20:24 UTC phase scan, some issue in the phase
• 21:07 UTC a\other phase scan and a long stretch of shot noise
• 22:16 UTC SQZ injection with phase equal to 4.25 rad
• 23:44 UTC stop injection and AA loop dither line

ITF found in COMMISSIONING, LN3_ALIGNED
17:00 UTC tuned squeezing phase scan (Vardaro)
18:05 UTC detuned phase scan: SRCL set set to 11
18:30 UTC HVAC oncall called due to a boiler failure at 1500W. Intervention scheduled for tomorrow morning, flag shelved for the night.
22:00 UTC At the end of the shift I left the ITF in COMMISSIONING, LN3_ALIGNED

The following report has been submitted to the On-call interface.

On-call events -> Air Conditioning

Title: WAB boiler failure

Author(s): andreazzoli

Details:

Due to the oil-fired boiler shutting down, the water temperature in the hot water circuit has dropped to 20 °C (set to 50 °C).
Boiler operation has been restored. The system is operational but requires a more thorough inspection, which will be carried out tomorrow morning. Soldani D. has been informed.

* Note that any files attached to this report are available in the On-call interface.

ITF Found in LOCKING_ARMS_BEAT_DRMI_1F State and COMMISSIONING Mode.
All times are UTC.
07:00 MAINTENANCE started.
07:09 Acl Update step 3 Started (Masserot).
07: 20 INJ beam blocked for INJ Acl Update (Gosselin, remote), then I requested DOWN to INJ_MAIN Metatron node and I paused ITF_LOCK.
07:27 Acl Update step 3 Completed for INJ and SQZ, while TCS, and SAT postponed afted the shutdown (Masserot, #68939).
07:35  INJ beam block removed (Gosselin, remote).
07:43 INJ in IMC_RESTORED.
10:43 ITF in LOCKED_ARMS_IR.
11:00 MAINTENANCE ended.
12:57 ITF in LOW_NOISE_3_ALIGNED;

Task performed by the operator during the maintenance:
- From 08:25 to 8:35 OMC Lock;
- From 08:38 to 08:59 OMC Scan;
- 09:08 TCS Chillers Refill;
- 09:18 TCS Thermal Camera Reference;
- 11:15 TCS Power Checks at the Pickoff:

This line's amplitude continuously decreased and cannot be clearly seen after midnight today.

In the injection alignment strategy, the vertical setpoint of the BPC is still defined by the DC NF QPD located on the EIB.

This morning, we performed a quick test to check whether this vertical setpoint has any impact on the RFC alignment. We shifted the beam by approximately 1300 µm and observed an increase in the RFC transmission of about 15% (see figure attached).

During the final steps, we also noticed that IMC_TRA increased to 18.2 W, then dropped to 17.4 W before the system eventually unlocked. Observing the reflected beam, it was clear that the beam was misaligned on the IMC, and its transmission was unstable.

We then returned the BPC vertical setpoint to its initial position.

Although this does not necessarily mean that the RFC misalignment originates from this vertical shift, it would be worth dedicating more time to investigate whether a different IMC alignment, combined with a higher BPC Y setpoint, could lead to improved RFC transmission.

All NCals have been stopped during the maintenance.

I expect this bump to be due to the squeezer shutter being opened but the squeezing not being injected. From what I remember the shutter on SDB1 towards squeezing was openend on March 12-13, then closed for the weekend and reopned in the middle of the week. And it has remained opened since then.

This wandering line was likely already present in the March 13 data, but not in the March 12 data, i.e., during the first recovery after the electrical shutdown. The onset of the source may therefore be uncorrelated with the shutdown.

I am attaching two plots showing the median-normalized spectrogram of the strain: one covering March 12–13, and another starting from March 18, where the spectral line is particularly visible with the better sensitivity in the detuned SR configuration achieved in recent days.

Could be related to this issue found in the past: #61815?

The Acl's servers running on the following rtpcs have been restarted with the Acl release v1r39p17

• ASL rtpcs : rtpc22 (trend plot), rtpc24(trend plot)and rtpc10 (trend plot)
  • Operations performed between 2026-03-23-06h22m00-UTC and  2026-03-23-06h39m45-UTC
  • the ITF has been unlocked at 2026-03-23-06h30m21-UTC  to performed the update of the Acl's rtpc server.
  • After these operations the ITF has been successfully locked upto LOW_NOISE_3_ALIGNED  at  2026-03-23-07h10m46-UTC
  • ITF unlocked  2026-03-23-07h23m08-UTC to continue the Acl deployment 
• SPRB and LNFS rtpc: rtpc6 (trend plot)
  • LC and SBE loops openned 
  • Operations performed between 2026-03-23-07h25m14-UTC and 2026-03-23-07h33m42-UTC
  • LC and SBE loops successfully closed 
  • After these operations the ITF has been successfully locked upto CARM_NULL_1F  at  2026-03-23-07h45m21-UTC
  • ITF unlocked  2026-03-23-07h47m16-UTC to continue the Acl deployment
• SWEB  rtpc: rtpc9 (trend plot)
  • LC, SBE, PCAL and NCAL loops openned
  • Operations performed between 2026-03-23-07h47m55-UTC and 2026-03-23-07h59m27-UTC
  • LC, SBE, PCAL and NCAL loops successfully closed
  • After these operations the ITF has been successfully locked upto LOW_NOISE_3_ALIGNED at  2026-03-23-08h30m48-UTC
  •  ITF unlocked  2026-03-23-08h31m17-UTC to continue the Acl deployment
• SIB2 rtpc: rtpc18 (trend plot)
  • LC and SBE loops openned 
  • Operations performed between 2026-03-23-08h32m26-UTC and 2026-03-23-08h34m43-UTC
  • LC and SBE loops successfully closed
  • After these operations the ITF has been successfully locked upto CARM_NULL_1F at  2026-03-23-08h48m12-UTC
  •  ITF unlocked  2026-03-23-08h48m58-UTC to continue the Acl deployment
• SDB1, SDB2  rtpcs: rtpc1(trend plot) and rtpc13 (trend plot)
  • LC(SDB1,SDB2), SBE(SDB2) and OMC  loops openned 
  • Operations performed between 2026-03-23-08h50m27-UTC and 2026-03-23-09h00m26-UTC 
  • LC(SDB1,SDB2), SBE(SDB2) and OMC  loops successfully closed
  • After these operations the ITF has been successfully locked upto CARM_NULL_1F at 2026-03-23-09h17m-UTC , and to LOW_NOISE_3_ALIGNED at  2026-03-23-09h42m24-UTC

Acl 's upgrade  second block complete 

A faint but large spectral artifact (bump) can be seen wandering around the 50 Hz mains spectral lines as one can see on figure 1. This artifact can go down to around 40 Hz and seems to have appeared around march 17th/18th. It was not present at the beginning of february for instance.
Recent BruCo reports do not seem to find any coherent channels with it.

ITF found at CARM_NULL_!F, relocking up to LN3_ALIGNED. COMMISSIONING mode.

The planned activity on "Acl Update step 2 (Masserot)" went on without major issues from 07:00 to 10:00 UTC.
Infrastructure civil works by external company, close to MC building, from 11:00 to 13:00 UTC. ITF remained stable locked at LN3_ALIGNED.

considering all the channels:

DQ_BRMSMon_BRMS_SEA_SEIS_100mHz_200mHz_ENV_CEB_SEIS_N_mean. 

DQ_BRMSMon_BRMS_SEA_SEIS_100mHz_200mHz_ENV_CEB_SEIS_V_mean

DQ_BRMSMon_BRMS_SEA_SEIS_100mHz_200mHz_ENV_CEB_SEIS_W_mean

DQ_BRMSMon_BRMS_SEA_SEIS_300mHz_500mHz_ENV_CEB_SEIS_N_mean

DQ_BRMSMon_BRMS_SEA_SEIS_300mHz_500mHz_ENV_CEB_SEIS_V_mean

DQ_BRMSMon_BRMS_SEA_SEIS_300mHz_500mHz_ENV_CEB_SEIS_W_mean

we can set the limits for which it is more probable to be not locked than locked