We investigated the missing signals on WI MIR local controls.

Spinicelli noticed that the SLD switch was off and flipped it, turning the beam back on. We realized that the contact between the power cord and the switch box is very precarious and turning or touching the cord is enough to turn the laser off again. We carefully adjusted its position until it worked, but it is clearly a non ideal situation and we will need to replace either the cable or the box itself.

After turning the SLD back on, we noticed periodic glitches on WI_MIR_PSDF in the form of a ~1s long burst followed by two large glitches, spanning ~1 V peak to peak. This structure repeats every ~5 seconds (Fig.1).

We investigated this behavior by opening the local control box and swapping the cables between the amplifiers of the PSDF and PSDI photodiodes, both the power cables and the data cable connecting them to the photodiodes. The issue remained on PSDF, which led us to conclude that the amplifier itself was malfunctionig and we removed it to substitute its components.

Surprisingly though, the PSDF signal still shows the same glitches without the amplifier (Fig.2), meaning that the issue is likely downstream, possibly at the level of dsp electronics. We will contact Boschi to investigate.

The current situation is that the signal is disabled, with the amplifier uninstalled and currently sitting in the Roma 1 office in the office building. We will reinstall the amplifier and restore the previous situation tomorrow morning, as the components inside the optical levers box are clearly not at fault for this issue.

Critically, the PSDF signal serves as reference for the WI's alignment and it must be restored in some form before uninstalling the mirror.

During the operations I had to move a magnetic field sensor out of the way to access the optical levers box. I repositioned it as precisely as I could and informed Tringali and Fiori afterwards.

As a first step towards the commissioning of the BPL this afternoon we installed a mirror before the EOMs on EIB to send the main beam on a divergent lens (-30mm and then a beam dump), so that we will be safe while doing tests on the PZT (the risk would have been to burn something since the power density at the level of the EOMs is high).

We added 2 mirrors, 1 lens, 1 beam dump, and removed 1 iris, for a weight of about +1kg. We rebalanced the EIB and left it suspended. The PMC is scanning and the mirror at its output is flipped.

Tomorrow we will plug the PZT to the DACs and start the commissioning of the QPDs.

This morning, we upgraded the machine hosting both the database and the web component of the DMS service.

The procedure was carried out as follows:

1. The servers were stopped to prevent any further database writes.
2. The database was copied to the test environment, where the application code had already been verified and updated in preparation for the upgrade.
3. The old production machine was powered off, and the test machine was cloned and renamed using the original production hostname.
4. The new machine was moved to the same Pool as the previous production system.
5. The new machine was activated.
6. Both backend services and the web interface were verified to be fully operational.

New system configuration:

• Server: AlmaLinux 9
• Web Server: Apache 2.4 (php-fpm)
• PHP: 8.3.30
• Database: MariaDB 10.5.29
• phpMyAdmin: 5.2.3

The entire process took approximately 2.5 hours, from 09:00 LT to 11:30 LT, during which the DMS service was unavailable. Most of the time was spent copying the database, particularly the tables containing plot data.

The application code had been previously tested in the environment. No anomalies have been detected so far; however, the system will continue to be monitored over the coming days.

Two flip mirrors on the EIB ALS path, one to cut the IR seed and the other to remove only the green beam, are now installed and remotely controllable via VPM, on the TTL_inj server, under TCS section.

They are named respectevely ALS CEB IR and ALS CEB GREEN.  

During the opening of the NI tower, vacuum team observed that the ZnSe viewports show patterns as visible in Fig. 1 and Fig. 2 (Fig. 1: diagnostic viewport, Fig. 2: PAM viewport). These patterns suggest a possible delamination of the optical coatings from the window surfaces. Part of the coating material has already been collected by the vacuum team and will be analyzed via Scanning Electron Microscopy (SEM).
By visual inspection performed by Antonio and the vacuum team, no cracks in the ZnSe substrate have been identified.
A preliminary inspection of the viewports at WE and NE has been carried out by the vacuum team. It is noted that, at the end towers, only one viewport per tower is present (unlike the input towers, where two viewports are installed). The viewports appear to be in acceptable condition from the outside, although visibility is limited. The pattern is instead clearly visible from the inner side of the tower.
A further inspection of the WI viewports will be performed by the vacuum team as soon as possible.

Starting from the 9th of April, Angelo pointed out some slow glitches appeared  in the VAC_TOWERIB_MG1_CH4 channel.

I ve taken the set of data from the 9th of April up to now and I ve automatically detected the gitches, see Figure 1.

I' ve then compute the rate of the glitches, figure 2, and I' ve tried to correlate them with some temperature probes that Maria provided me

namely 'ENV_IB_F0_TE2';'ENV_IB_F4_TE1';'ENV_IB_F4_TE2';'ENV_IB_F7_TE1';'ENV_IB_F7_TE2'

no correlation has been found with these channels

investigations still on-going

Today, after the dismountling of the two baffles in front of the mirror (HR side) by L. Naticchioni e M. Ricci, I applied First Contact on the payload HR surface.

Before applying the FC, I inspected a bit the surface and I could spot many dust particles (Figs. 1 to 2). I could also find a big scratch on the upper left side of the mirror (Fig. 3). Moreover, it was possible to observe by eye the big point absorber found previously with the thermocamera (VIR-0106A-26) roughly at 9 cm to the right wr.t. the center of the mirror (Fig. 4). Measuring it on the picture, a slight more precise estimation is 8 cm, instead of 9 cm.

Figs. 5 to 7  show the FC application process and the completed work. 

ITF found in UPGRADING Mode and DOWN State.
All times are UTC.
06:57 TCS Chillers refill (Ciardelli).
08:21 West arm large valves opened (Vacuum team).
From 09:02 to 09:07 TCS WI CO2 Power Checks (Operator).
From 09:26 to 09:29 TCS WI Thermal Camera References (Operator).

During the shift the West Arm IR was recovered and ALS green was checked (Spinicelli, Pinto, Casanueva, De Rossi, see #69072).
ITF left in UPGRADING Mode and DOWN State, measurements on the PR suspension ongoing (Boschi).

TCS WI CO2 Power Checks:

Today we have checked the green lock after the installation of the source in the EIB bench. The motivation of this action was to reduce the amount of fiber used in the propagation of the green, since the air conditioning in the Laser Lab was producing noise that was strongly polluting the error signals.

We first aligned the west arm and locked the infrared without major problems. Then we locked the green in reflection of the west arm, which locked without major problems as well. At this point we checked the signals seen by the PDs in teh central building (ALS CEB WARM BEAT 154MHz). There is no saturation, we have slightly improved the "mag", and the spectrum of the error signal that we used (_dFreq) has improved a lot at high frequencies where we were dominated by the air conditioning noise (see Figure 1). The rms has improved by a factor 4 (our-of-loop).

We will have to wait to have both arms to check the passage to CARM/DARM but the target will be to increase the UGF of these loops. In order to check that we are no longer limited by the ambient noise we will make a test of turning off the air conditioning.

After the successfull deploiement for the WEB NCAL , we continue to use this new firmware on WEB and NEB PCal system and for the NEB NCal one.

Below the list of the operations performed:

• WEB PCAL system
  • Update the DAC1955-SN11 (WEB_PCAL_DAC) located in the DBOX-SN49 with the v3r3 release for the FPGA firmware and the DSP code
  • Update the WEB_PCal_fast Acl server 
  • Update the WEB_PCAL_DAC part in the SWEB_dbox_rack DBox server and reconfigure it 
  • After these operations the WEB_PCAL loop was successfully close
  • operations performed between 2026-05-05-06h49m50-UTC and 2026-05-05-07h27m54-UTC 
• NEB NCAL and PCAL systems update
  • Update the VPM Online configuration to use the DaqBox v17r9 for the SNEB_dbox_{bench,rack} servers
  • Update the DAC1955_SN6 (NEB_DAC_NCAL0) ) located in the DBOX-SN118 with the v3r3 release for the FPGA firmware and the DSP code
  • Update the DAC1955_SN18 (NEB_DAC_NCAL_TCS) located in the DBOX-SN119 with the v3r3 release for the FPGA firmware and the DSP code
  • Update the DAC1955_SN121 (NEB_DAC_PCAL) located in the DBOX-SN35 with the v3r3 release for the FPGA firmware and the DSP code 
  • Update the NEB_NCal server configuration
  • Update the NEB_PCal server configuration  and  the NEB_NNC_Tilt server configuration
    • these 2 servers are sharing the same DAC1955_SN121 (NEB_DAC_PCAL) but each one sends a Tolm packet  related to its used channels
  • Update the SNEB_dbox_rack configuration to set the related DAC1955 boards configuration
  • operations performed between 2026-05-05-08h28m20-UTC and 2026-05-05-09h39m12-UTC
  • After these operations only  the NEB NCAL loops were tested and all were successfully closed 
  • for the NEB_rtpc, the output data flow related to the DAC1955 boards was reduced from 29.4MB/s to 19.3MB/s 

We have re-verified the angular and longitudinal WPs after the work of today.

The new values of the angular WP are close to zero but the horizontal FF. We will investigate the reason for this difference in the following days.

NF H: -0.02

NF V: -0.075

FF H: -0.62

FF V: -0.05

Instead the longitudinal WP remained quite large as measured last week (-1.7V).

Last Thursday a large longitudinal working point offset was observed in the IMC locking loop. In addition, the RF QPD in near field used for IMC alignment did not appear to behave correctly.

Given the significant mode mismatch previously measured (~13%), we redistributed the power by reducing the PMC input by 20% and compensating with IPC1, with the aim of modifying the thermal lens in the EOM and Faraday. Following this change, the mismatch improved to ~9%.

In parallel, a peak at 0.8 Hz was identified in the RF QPD spectra. Maria and Irene performed a Bruco analysis and found coherence with MC TY, suggesting that the feature originates from the AA matrix.

We then optimized the IMC alignment and remeasured the sensing matrix. The 0.8 Hz peak on the horizontal signals was significantly reduced (see comparison plot between Apr 10, this morning before power reduction, and now). However, the longitudinal working point remains large and comparable to last week. Checks of the 22 MHz signal and the RF photodiode after the EOM (EOM_EAB_TRA) do not show any increase in amplitude modulation, leaving this effect unexplained.

To further investigate the mode mismatch, beam profile measurements were performed on EIB after M5 under two thermal conditions: current configuration and with PMC_TRA increased by 20% (as earlier this morning). The goal was to identify possible thermal lensing, including its position and focal length.

Measurements (around 17:17 LT, low PMC power, 29.6 W after EIB M5, IPC1 = -54250 step, ~4.4 mW sampled after M5) :

z from M5 (mm)   ellipticity  beam width (um)

85        97      1280 um
135    98%      1290 
185      100     1380
235      100     1420
 285                1470
 335                1480      (1530)

After increasing PMC_TRA by 20% (17:24 LT, ~5.3 mW sampled),

      85mm      97%                  1260
            135       98                   1305
            185       99                   1360
            235       97                   1405
            285       96-97              1490
            335       98                   1520

The measurement sequence ended at 17:37 LT, and the system was returned to low PMC power at 17:44 LT (IPC1 = -51500).
 

A preliminary analysis of the beam profiles indicates a waist of ~508 µm located at -0.49 mm from M5 in the low-power case, and ~444 µm at the same position in the high-power case (+20%). Using the known waist at the output of the LB (639 µm at 13 cm from EIB), these results can be reproduced by introducing a thermal lens in the third EOM with a focal length of ~1090 mm (low power) and ~900 mm (high power). The variation in focal length is consistent with a linear dependence on absorbed power. Quantitatively, this would correspond to an effective absorption on the order of ~2000 ppm, significantly larger than the expected 50 ppm/cm for a 20 mm crystal.To be followed.

Additional activity : 

Realignment and calibration of EIB POUT : 34.5 W on the channel with 0.485 PMC_TRA_DC  while 29.6 W have been measured.

This afternoon we put in operation the DAC1955 v3r3 firmware for the NCAL WE . After the upgrade; the WEB NCAL loops, frequency and phase, were successfully closed.

Below the details of the operations:

• use DaqBox v17r9 version for the  WEB rtpc DaqBox servers
• update the DAC1955 SN53 (DBox SN121) and DAC1955 SN73 (DBox SN 175) firmware qnd DSP code with the v3r3 release
  • The DAC1955 chips are now running  at 400KHz instead of 100KHz previously,  with an analog anti-image filter cut-off unchanged at 20KHz
• update the SWEB_dbox_rack configuration and the WEB_NCal one
• operations complete at 2026-05-04-14h46m00-UTC

ITF found in down and in Upgrading mode.

Below the list of the activities communicatd in control room:

• NI payload intervention; in progress.
• Instrumented baffles installation; in progress.

Cal

At around 11:30 UTC Alain started to work at WE Pcal.

Susp

At 12:34 UTC we had a problem with the DSP BPC board. I contacted Valerio and he fixed the problem performing the download of the code.

SBE

The DMS was reporting that SPRB_SBE vertical correction was close to saturation; I recovered it using the stepper motors.

A few more observations concerning the test of April 23:

• at some point, while the AHU was off, we stopped the water flux by closing the valves located inside the CEB AHU room. Unespectly we measured an increased acoustic noise in the range 50 to 100 Hz (Figure 1)
• between 8:49 and 11:13 UTC, while the AHU was off, we closed all air valves of ducts (all set to 0%). In principle we would expect some change in the position of low frequency spectral peaks, if they were associated to acoustic modes of the air ducts. We did not notice any change (Figure 2).
• acoustic spectrograms show some peaks changing frequency, mostly above a few hundred Hz. They seem correlated to the frequency of the SUPPLY fan (Figures 3 and 4). Yet, we then notice that similar ones are present also when the HVAC was running in MANUAL modes (that is when both fans frequency fixed): Figure 5. Could they be associated to the air flow regulators instead?

- IMC alignment and measurement of the new AA sensing matrix

- IMC longitudinal wp. The offset on the IMC PDH error signal appears to be quite large (-1.6 V, see attached plot). However, with this offset the IMC lock is very unstable, so we left the old one -0.07 V. To be understood why the scan gives such large offset (maybe on monday we will check the alignment in the EOM? on the IMC refl photodiode?)

- IMC Fmoderr. We made it with the automation and it was very close to the optimal wp

- IMC angular wp --> we found an issue on the NF V RF quadrant.  We did the usual scans of the galvo working points (scanning the offsets of the galvos) and look at the coupling between error signal and frequency noise (TF between perturb at 1111Hz and the Quadrant signal (the demodulated quadrature I). We observed a strange behaviour for te NF V (non linearity: changes slope around the 0). See plots 2 and 3 which compare current scan (30 Apr 13:17:02 UTC) with an old one (10 Apr 2026 10:03:10 UTC): the magnitude doesn't go to zero and the phase behaviour looks strange. We then went in the LL Atrium and unpowered and powered again the NF QPD electronic box and made another scan at utc2gps(2026,04,30,15,05,08) from -0.5 to 0.5 in 300s (plot 6 and 7), which was still bad. To be investigated next week.

- IMC OLTF we found 96 kHz UGF and 30 deg phase margin. We added 1 dB to get 107 kHz and 23 deg phase margin (plot 8)

In the meanwhile we prepared the Acl code ISYS_BPL for the bench pointing loop. We still have to plug the PZTs to the DAC (we need prior to find a solution to block the beam before the EOMs while testing the PZTs, since the risk would be to burn something)

Here attached some pictures of the EIB after the installation.