ITF found in COMMISSIONING Mode and LOCKED_ARMS_IR State.
All times are UTC.
07:55 - 08:35 INJ: Damper removal to allow refence beam reaching phase cameras (Melo, Tacca, #69570).
08:54 - 09:55 ISC: B4/B1p PC realignment, works on EPRB (Tacca, Guo, Bothra).
10:05 - 10:39 INJ: PC pickoff alignment (Melo, #69572).
12:09 - 13:10 ISC: Installation of PC enclosured on EPRB (Tacca, Guo, Bothra).
13:44 - 14:53 DET: Checks in DET Lab (Tacca, Guo, Bothra).

The work during the shift was the Check of Phase Camera alignment carried out by Bothra, Guo, Melo, and Tacca (see #69578).
ITF left in COMMISSIONING Mode and LOCKED_MICH_HF_DC State.

We checked the alignment of both B4 and B1p phase cameras profiting of the interferometer locked with MICH at half fringe.
Work for B4 phase camera:

• at first we removed the scanning FP and its auxiliary optics since it has not benn used for a long time (scanning FP and photodiode have been stored by Suzanne);
• then we checked the superposition of the reference and the B4 beams: even if the power on B4 is not too high, we were able to optimize the superposition between the two beams. We had to remove the neutral densities on the reference beam path since the coupling of the pick-off beam into the oprical fiber in the laser bench is good but not yet optimized (see entry 69572);
• we barely centered the photodiode and we are happy for the time being;
• we added a new cover on the bench to sheld the laser beam (see pictures 1 and 2).

Work for B1p phase camera:

• we checked the superposition of the reference and the B1p beams and it was already almost good;
• as requested by Romain, we add a beam dump on the reference beam path for the SDB1 intervention scheduled for next week (see picture 3).

Figure 4 shows the beams acquired by the phase cameras after the intervention: B4 is not perfectly centered, we will optimize its alignment once all the alignment loops are engaged in CARM NULL; B1p is showing fringes, we checkd the path of the beam on the bench and we realized that the fringes are coming from the ITF, probably due to some clipping on the suspended benches not perfectly aligned at this stages.

Next steps:

• Remove the beam dump fon the B1p path after the SDB1 intervention;
• Together with INJ people, optimize the coupling into the fiber on the laser bench for the reference beam. Don't do it before installing back neutral densities on EPRB to avoid to burn the photodiode;
• Optimize the superposition of the beams and the alignment of the photodiodes once the alignment loops are engaged in CARM NULL.

Some issues occured last week in the RDS stream on the archive_50Hz directory : as consequence  the rds Frame File list was built with some frame files not correctly handle by the Fd library .

To avoid this kind of issue, the Fm package has been upgraded in the v5r00 release

• to  check the expected frame file suffixes 
• to choose the correct frame file location as the same file could be in the online frame disk buffer or in the archive one 

After some tests, this release has been put in operation on the VirgoOnline Fm servers :

• operations performed between 2026-08-13-10h12m58-UTC and 2026-08-13-10h32m24-UTC

Since the power on the phase camera was very low, M. Tacca asked me to align the reference beam. So, I went to the LL and with the two mirrors in front of the phase camera pick-off in fiber I tried to align the beam around 12.30h LT. For the alignment, I took as reference the channel EPRB_B4_PC_CAR_PWR and the corresponding camera image. The alignment is not easily done since the mirrors are difficult to reach by hand, but some improvement could be done as shown in the attached image. 

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

On-call events -> Air Conditioning

Title: Chiamata per bassa pressione circuito aria TERMINALE NORD

Author(s): Pezzimenti

Details:

Ho ricevuto intorno alle ore 4:00 circa di sabato 8 agosto un messaggio sul telefono del reperibile, per un allarme di bassa pressione nell'edificio tecnico del Terminale Nord. Chiamando Andreazzoli Sergio (persona di riferimento in quel periodo), Ha ritenuto necessario fare un controllo il giorno seguente di buon ora, in quanto la linea comunque era supportata dall'altro compressore, ed i valori sulla linea finale di pressione erano nella norma. Arrivato sul sito, trovo il selettore rotativo MANUALE su "0" quindi SPENTO. Ho ripristinato il selettore ruotandolo su "1" quindi "ACCESO", ed il compressore è ripartito senza che effettuassi nessun'altra operazione. Ho atteso che anche quella linea tornasse nei valori di pressione stabiliti, confrontandomi sempre telefonicamente con Andreazzoli. Per sicurezza ho fatto anche un controllo al Terminale Ovest, ma non ho trovato nessuna anomalia.

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

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

On-call events -> Air Conditioning

Title: Chiamata per bassa pressione circuito aria TERMINALE NORD

Author(s): Pezzimenti Francesco

Details:

Ho ricevuto intorno alle ore 4:00 circa di venerdi 7 agosto un messaggio sul telefono del reperibile, per un allarme di bassa pressione nell'edificio tecnico del Terminale Nord. Chiamando Andreazzoli Sergio (persona di riferimento in quel periodo), Ha ritenuto necessario fare un controllo il giorno seguente di buon ora, in quanto la linea comunque era supportata dall'altro compressore, ed i valori sulla linea finale di pressione erano nella norma. Arrivato sul sito, trovo il selettore rotativo MANUALE su "0" quindi SPENTO. Ho ripristinato il selettore ruotandolo su "1" quindi "ACCESO", ed il compressore è ripartito senza che effettuassi nessun'altra operazione. Ho atteso che anche quella linea tornasse nei valori di pressione stabiliti, confrontandomi sempre telefonicamente con Andreazzoli. Per sicurezza ho fatto anche un controllo al Terminale Ovest, ma non ho trovato nessuna anomalia.

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

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

On-call events -> Air Conditioning

Title: Chiamata per bassa pressione circuito aria TERMINALE NORD

Author(s): Pezzimenti Francesco

Details:

Ho ricevuto intorno alle ore 4:00 circa di venerdi 7 agosto un messaggio sul telefono del reperibile, per un allarme di bassa pressione nell'edificio tecnico del Terminale Nord. Chiamando Andreazzoli Sergio (persona di riferimento in quel periodo), Ha ritenuto necessario fare un controllo il giorno seguente di buon ora, in quanto la linea comunque era supportata dall'altro compressore, ed i valori sulla linea finale di pressione erano nella norma. Arrivato sul sito, trovo il selettore rotativo MANUALE su "0" quindi SPENTO. Ho ripristinato il selettore ruotandolo su "1" quindi "ACCESO", ed il compressore è ripartito senza che effettuassi nessun'altra operazione. Ho atteso che anche quella linea tornasse nei valori di pressione stabiliti, confrontandomi sempre telefonicamente con Andreazzoli. Per sicurezza ho fatto anche un controllo al Terminale Ovest, ma non ho trovato nessuna anomalia.

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

Today, around 10.30h LT we removed the beam dump after the amplifier on the laser bench to allow the work on the phase cameras. 

We (Matteo, Yuefan, and Yashwant) will enter in CEB to work on the phase cameras and confirm that there is no laser hazard to enter the building.

While we were retuning some step of the lock acquisition, the handoff of DARM to the IR was constantly failing due to an oscillation around ~70 Hz. We realized that this could be due to the missing structure at 68-72 Hz (fig.1), that we compensated in the DARM/CARM control filter while on the beating. Maybe its absence during the handoff was causing some stability issue.

We modified the controller in order to remove the resonant gain. After such modification, we succesfully performed a smooth transition to B1p 56MHz error signal.

We sligthly adjusted the beating control filter in order to recover the bandwidth and stability margins of yesterday, in order to cope with the 68-72 Hz structure, which was eating a lot of phase reducing the available margins. After the modification we recovered the situation of yesterday (performance wise). In fig.2 the comparison of CARM and DARM signal and correction spectra of yesterday (blue) and today (red) while locked on the beating.

We still don't know what is the structure of fig.1, but we know that we need that

:)

The goal of this commissioning task was to get the right configuration - arms resonant on IR beam with MICH in half fringe (HF), to get the PC reference images. This state, LOCKED_MICH_HF_DC, has been automated in the virgo system (virgoDev - Automation - userapps). It derives from the arms locked on IR (metatron state 40). Once this is achieved, the only d.o.f. to be controlled is the MICH. The LOCKED_MICH_HF_DC which is the desired state and its locking processes lives in the DRMI_LOCK.py and initialization of the locking process (gains, filter, weights, etc.) lives in DRMI_LOCK.ini.

To control the MICH d.o.f. we need the right error signal which can be used to lock when in the optimal configuration (half-fringe). The error signal used for MICH is the combination of the signals acquired at B4 and B1p. These signals are given by:

1. SPRB_B4_DC
2. SDB2_B1p_DC

which are in a.u. and something we don't care about. Since we know the min and max of these signals we can try to optimize the error signal for our configuration using dedicated weights. The error signal for the MICH d.o.f. is given by the combination of the afforementioned signals:

LSC_B1p_SUM_NORM = SDB2_B1p_DC/(SDB2_B1p_DC + w*(SPRB_B4_DC))

where w is the weight for the B4 DC signal. This error signal should range between 0-1 which triggers the lock on the MICH d.o.f. when it is in the desired range. Figure below (pc_calib3) shows the error signal channels and the signals which it is derived from. To get the perfct half-fringe this should be 0.5 (given it ranges between 0-1). In the current algorithm, the locking of the d.o.f. is triggered when the error signal ranges from 0.4-0.6 (range). Once the error signals were defined and the process automated, we were able to achieve a relatively stable lock for the configuration. One of these locked state of this configuration along with the MICH trigger and MICH correction is shown in figure below (mich_hf_lock4). The trigger being 1 means the target d.o.f. is locked. Also in the plot we can see the correction signals, of the MICH d.o.f. which acts on the BS. We use the BS to control this dof. The range of the correction is +/-10 V. As we can see that there is a lot of correction that is being applied to keep the dof locked. The error signal also fluctuates a lot between 0.45-0.55 which means we cannot narrow down our range of the error signal as it will loose lock once the threshold is crossed. Apart from these signals also plotted are the B7 and B8 DC signals representing the power transmitted through the arm cavities. The SPRB B4 and SDB2 B1p PDs are the powers (a.u.) measured in bright and dark port of the interferometer. The lock acquisition of the MICH dof shows a ramp (figure: mich_hf_lockstep3) which is not clearly understood why. The trigger should work as relay switch (0 or 1). 

In the next days we will also elaborate on the reults from noise injection on MICH control loop used in this configuration. 

ITF found in LOCKED_ARMS_IR and COMMISSIONING mode

06:00 UTC ADC7674_SN13 in the TCS room unreachable : problem solved by changing SPF connector on TCS ADC7674_13 (Masserot, Zaza, Kraja)

07:30 UTC Recombined configuration (Arms@IR, MICH half-fringe) (Bothra, Bersanetti)

08:57 UTC earthquake in Marina di Pisa, suspended benches recovered

13:30 UTC CARM/DARM handoff to IR (Bersanetti)

Quick recap of the past activity done on NI and WI payloads:

Over the past days, after the NI and WI payloads installation, some activity concerning the optimization of the driving has been performed. We focused on reducing the coupling among the longitudinal and the angular corrections at the level of the marionette.

North Input payload:
Concerning yaw (ty) and roll (tz), the usual procedure to estimate the driving coefficients has been performed. Iterative DC corr steps in the longitudinal DoF have been applied in order to estimate the correct driving coefficients which minimized the couplings among the different DoFs.

For what it concerns the coupling between length and pitch (tx), other than DC constant coefficient (same as for ty and tz), above about 100 mHz there is an additional non negligible frequency dependent component which is mainly related to the mechanics of the payload, which couples the pitch rotation of the system for a given longitudinal force applied to the marionette.

This mechanical component is usually implemented as a filter filtering part of the Z correction going in the tx correction branch (zC-txC).
In order to estimate the new zC-txC filter we injected noise separately in the Z driving and TX driving, in different working conditions in order to estimate differences within the angular spectra for different driving implementation. Namely, relevant GPS are the following:

gpsZc=utc2gps(2026,08,05,14,05,00); durZc=2400; % noise zC in WI and NI with old compensator zC_txC
gpsZcWI=utc2gps(2026,08,05,14,48,00);durZcWI=1000;  % noise zC in WI with NO compensator zC_txC
gpsZcNI=utc2gps(2026,08,05,14,48,00);durZcNI=2400;  % noise zC in NI with NO compensator zC_txC
gpsNItxc=utc2gps(2026,08,05,15,31,30);durNItxc=2400; % noise TXc in NI
gpsWItxc=utc2gps(2026,08,05,16,40,00);durWItxc=1000; % noise TXc in WI
gpsZcNI2=utc2gps(2026,08,11,14,35,30);durZcNI2=900;  % noise zC in NI with NEW compensator zC_txC

The zC-txC filter is extracted by computing the ratio between the two measured transfer functions of TX opLev response over Zcorr and TX opLev response over TXcorr during the several noise injections.
Results of the measurements are reported in fig.1, where in blue is reported the overall zC-txC transfer function, from which the DC flat coefficient has been obtained, while in red the consequent residual frequency dependent filter, to be fitted and implemented, is reported. In fig.2 the fit of the compensator is shown.
In fig.3 are reported the comparison of the NI TX opLev signal in different time stamps, during Z corr injections, i.e. the initial condition with the older driving compensator (blue), the same signal with the compensator switched off (red), response with the new implemented global driving (both tx, ty and tz), with only the DC coefficient for txC applied (yellow). Final response with the final driving configuration with also the zC-txC frequency dependent compensation implemented, is reported in the purple trace.

Both in the yellow and in the purple plots, the coupling reductions is evident with respect to the initial conditions, apart from mainly the region of the pendulum resonances, namely 0.4 and 0.7 Hz.

For reference, in fig.4 and 5, response of NI TY and TZ local control signals at the same gps time stamps are reported.

West Input payload:
Driving optimization has been performed as well for the WI pay. Result of the activity can be appreciated by looking at the clean data, while locked on the arms, in particular the TFs between the angular corrections and the longitudinal one before (blue) and after (red) the activity, see fig.6.
Concerning zC-txC frequency dependent compensator, same measurement done for NI has been done also for WI, by obtaining similar response to be fitted (fig.7). This compensator has not been implemented.

In the next future, we will explore the option to investigate further the length 2 pitch coupling, in particular in the region of the resonances, if there is a way to improve it.

We went to investigate in TCS room and DAQ room and found the following:

TSC room ADC7674_SN13 link0 : TX light red instead of green

DAQ room , Rack 15, MxDx SN12 link21 : RX arrow (DOWN arrow) ligh off instead of on

Since we already were in DAQ room, we first unplugged/replugged the fiber and tried to change the SPF connector, with no results. Moving on to TCS room, we changed the SPF connector with a spare one, the TX light went back to green and the data were restored shortly after.

An earthquake (3.7 mag) coming from Marina di Pisa unlocked the INJ system this morning at 8.57 UTC as EIB started to shake a lot. After some time the system recovered by itself. 

Some settlement earthquakes could disturb the system soon.

Cecilia fixed the issue by making the investigations and by replacing the fauly optical transceiver at the ADC7674 SN23 level  .

Operation performed at  2026-08-12-07h28m38-UTC

Since 026-08-12-01h12m40-UTC the ADC7674_SN13(TCS_ADC_Moni0), located in the TCS room, is unreachable via the Tolm network .

As consequence, the follwing servers became blue in the VPM interface: SUSP_SBE_Tpro, SUSP_Fb, TCS_CEB  and PyTCS 

Below the report  of the SUSP_Fb Tolmframebuilder, collecting the data sent by the TSC_ADC_Moni0 :

2026-08-12-01h12m37-UTC>WARNING-[TolmFrameBuilder::ControlMerging] frame: 1470532375.600000000: merging is triggered on timeout (internal 1470532375.962515050 > max 1470532375.960000000)
2026-08-12-01h12m37-UTC>WARNING-[TfbSubFrame::Fill] GPS: 1470532375.600000000 - Source TCS_ADC_Moni0_0: 452/2000 missing packet(s), 0 data break(s) (missing data are at the end of the vector)
2026-08-12-01h12m38-UTC>INFO...-[TfbSourceManager::Clean] source TCS_ADC_Moni0_0 (1595:v05) has stopped -> waiting for data...
2026-08-12-01h12m38-UTC>INFO...-[TfbSourceManager::Clean] source TCS_ADC_Moni0_Monitoring (1601:v01) has stopped -> waiting for data...
2026-08-12-01h12m38-UTC>INFO...-[TfbSourceManager::Reporting] Sources reporting: / nSrc: 57, missing(2): TCS_ADC_Moni0_0, TCS_ADC_Moni0_Monitoring
2026-08-12-01h12m38-UTC>INFO...-CfgReachState> Active(Active) Ok

The faulty ADC7674 SN13 is located in a VME 21slots crate with the 3 others TCS ADC7674 boards.

The 3 others ADC7674 data are correctly received, so someone should check first the optical transceivers at boths sides

• TSC room ADC7674_SN13 link0
• DAQ room , Rack 15, MxDx SN12 link21 

ITF found in LOCKING_ARMS_IR State and COMMISSIONING Mode.
All times are UTC.
07:50 - 08:20 INJ: IMC OLTF (Melo, #69545). 
08:31 - 08:51 DET: OMC Lock in SINGLE_BOUNCE_NI, locked from 08:44 to 08:49 (operator, see Fig 1).
08:52 - 09:13 DET: OMC Scan in SINGLE_BOUNCE_NI (operator, see Fig 2).
09:13 - 09:17 INJ: Chiller refill (Melo, #69549).
09:27 - 09:42 DAQ: Solving timing issues on SQZ DaqBoxes (Masserot, Pacaoud, #69548).
09:37 - 10:12 TCS: Thermal Camera References (operator).
09:20 - 09:40 INJ: RFC OLTF (Melo, Ruggi, #69546).
09:50 - 10:11 SQZ: Block SQZ beams towards SQB1 (Sorrentino, 69550).

The work on CARM/DARM handoff to IR went on during the afternoon. 
TCS: Power Checks skipped (requested by experts).

ITF left in COMMISSIONING Mode and LOCKED_MICH_HF_DC State with work on recombined configuration (Arms@IR, MICH half-fringe) (Bothra, Bersanetti) ongoing.

After the recent Free Space implementation, today we tested new control filters for CARM and DARM while locked on the beating signals. The idea was to make more robust the lock on the green by increasing the bandwidth of the loops.
In fig.1 is reported the comparison of the OLTF of DARM (for reference) with the older controllers (blue), the extracted model (red) and the new open loop TF with the new controller. We were able to increase the accuracy pushing up the badwidth to ~25 Hz (G.M. of a factor 2), by adjusting the roll-off in order to not renintroduce too much correction noise. To be noted that there's still margin to increase the bandwidth without occurring towards corr saturations, in case it is needed (see fig.3).

In fig.2 is reported the plant measurements. Both in DARM and CARM a notch strutcture at around 70 Hz was present. After some digging in Acl we found that in CEB_ALS process, filters for CARM and DARM (double structure at 68 and 72 Hz) are implemented in order to compensate some INJ structure (?). During the controller design we compensated this structure with a resonant gain at the same frequencies and Qs, so to gain more phase at that region.

In fig.3 are reported the first comparison of DARM and CARM signals and corrections spectra before and after the implementation of the new control filters. In order to reduce the bump visible at ~50 Hz and to reach the declared factor 2 of gain margin, we slightly adjusted the loop gains accordingly.

N.B.

modification performed (automation side) are the following:

• DARM/CARM control filter: ALS_Arm_control4 -> ALS_Arm_control5;
• carm_gain_boost_final: 0.006 -> 0.0138;
• darm_gain_boost_final: 0.018 -> 0.0138;
• darm_line_ampl: 0.07 -> 0.03;

I noticed that the pixel size of the camera SDB2_B1s2_Cam set in the configuration of DET_Img_CEB is wrong. It is currently defined as 5.2 um (the pixel size of the Smartek CMOS  GC1281XM-S90-NoCG). However this camera is not a CMOS one. Instead this camera is a Smarteck CCD GC1392M-A90-NoCG, for which the pixel size is 6.45 um.

The consequence of this mistake is that the beam size extracted from the camera images is underestimated by a factor 5.2/6.45 = 0.806 (almost 20%).

This mistake is probably present since 09/07/2019 when the B1s2 camera was replaced ( https://logbook.virgo-gw.eu/virgo/?r=46309 ).

We will fix this mistake next week when we will have the opportunity to restart the process DET_Img_CEB.

This morning around 10 UTC I put two dumpers in front of the output windows of the EQB1 bench. This will prevent any beam to reach SQB1.

There was the following DBoxes with the timing_error not at zero , this appeared around 08h50m-UTC for most of them:

• EDB_DBOX_OMC (SN075) and EDB_DBOX_SQZ(SN120) managed by the EDB_QD_dbox_rack server
  • Related to EDB_DBOX_SQZ(SN120), the demodulation board SN38 (mezzanine3) appeared as not available for the DaqBox server, but was weel reachable from the DBox ARM CPU
    • from the DBox ARM CPU; the command /home/daqbox/virgo/App/DaqBox/v8r3/scripts/daqbox_main_fpga_reset.sh  was executed and after the the faultymezzanine was recovered
  • The reconfiguration of these DBoxes allowed to recover the synchronization with the Timing system
• SQB1_DBOX_Up (SN103) and SQB1_DBOX_Up(SN104)  managed by the SQB1_dbox_bench server
  • the LC and SBE SQB1 controls were openned 
  • The reconfiguration of these DBoxes alloweed to recover the synchronization with the Timing system
  • the LC and SBE SQB1 controls were successfully closed after these operations
• EQB1_DBOX_03 (SN091) managed by the SQB1_dbox_rack server and the SQZ_DBOX_O2 managed by the  SQZ_DBOX_DET_EERoom server
  • The reconfiguration of these DBoxes allowed to recover the synchronization with the Timing system

After these operations, all the faulty DBOxes are synchronized  as well the FAST_DAC mezzanines . The attached plot show the trend of the issues