As observed by Federico, the metronix magnetometer in MCB is having an issue starting from 2023 October 2 UTC 00:03:03 (Figure 1). The signal looks corrupted (Figure 2).  This does not seem an issue with the ADC and neither with the driving electronics, since other channels sharing the same boards are fine. We will investigate further at next maintenance.

This fauty condition was not signalled by the DMS DeadChannel since the associated rms was smaller than the set threshold. The rms threshold has been updated (0.35 to 1 nT) and this channel temporary shelved.

This morning we realized that the name of  two channels of the episensor placed on the Laser Bench are not in agreement with naming convention. The same happen for the single axis episensor placed on the south-flange of SIB1.

To solve this problem:

- the channels: ENV_LS_SEIS_X and ENV_LB_SEIS_Z were exchanged;

- the channel ENV_IB_SEIS_Z was changed to ENV_IB_SEIS_X.

In figure 1 the coherence between the horizontal channels of the episensors placed on Laser Bench and External Injection Bench are compared before and after the change. The coherences of the sensor on the flange, with both ther sensors on the benches, before (figure 2) and after (figure 3) the change .are also reported.

Around 9:30 UTC we moved the ENV_DT_TURBO_MAG magnetometer closer to the DT turbo pump body, as illustrated in the attached picture. The read axis is X (radial direction).

Previous locations are described in https://logbook.virgo-gw.eu/virgo/?r=63394

Figure 1 shows a spectrum at 401 Hz of this sensor compared to the magnetometer on the DT tower base. The sensor on the pump body measures a quite intense 401 Hz line (approx 500 nT/sqrtHz). Yet, it does not see the sideband structures which are seen by the DT magnetometer and which were sensed close to the turbo cable.

This morning, during the work to restart the tiltmeter, we installed a couple of auxiliary probes. In particular: a seismometer, placed very close to the tiltmeter (see photo), and a couple of temperature probes inside the tiltmeter vacuum chamber. The new seismometer channels are: ENV_NEB_SEISM_T_N, ENV_NEB_SEISM_T_W and ENV_NEB_SEISM_T_V, with the usual orientation, while the temperature channels are: ENV_NEB_TILT_VAC_TE (probe placed on the chamber wall) and ENV_NEB_TILT_JOINT_TE (probe placed close to one of the suspended arm's joints). In the plot the coherence between the two seismometers and a comparison of the spectra are shown. A good coherence is visible up to about 10 Hz.

Since October 17 the weather station at WEB was producing flat (== zero). Today we fixed the problem. The problem has been tracked to the ethernet bridge, in particular to a faulty cable (Fernando). Having fixed this the meteo station device was able to reply to the "ping ethenv-web". It was also needed to stop/restart the dedicated server  BcMeteoWe in VPM (Rosario).

The red flag in the DMS "Flat channel" section is now cleared.

This afternoon the slow monitoring module ENV-NI (not working since last 2 June) was repaired. During the cheks after the installation, I realized that by connecting the probe ENV_NE_F3_TE2, the module stuked (probably this was the cause of the initial mulfunctioning), so I left it unconnected. The remaining probes seems ok. The temperature inside the NI tower are now again available.

We switched off/on the Large WEB coil interface module and the the ethernet connection recovered (ping relais2-3). The LargeWEBCoil server in VPM is now active. We verified also the the ON and OFF of the coil works.

The "cross-talk" problem is something that Rosario knew it might happen for "mixed" NEXUS boxes like the one to which microphone ENV_WEB_MIC and two accelerometers, ENV_WE_ACC_Z and ENV_WE_CT_ACC_Z, are connected.

Today we  disconnected the microphone (ENV_WEB_MIC) from the "mixed" NEXUS box and connected it to the second "microphone only" NEXUS box which currently powers ENV_WE_ALS_MIC.

The cross talk clearly reduced and apparently disappeared (Figures 1 and 2). Channels ENV_WE_ACC_Z and ENV_WE_CT_ACC_Z are cleaner now and resemble what we expect from those accelerometers, like the 1/sqrt(f) intrinsic noise below  10 Hz or so. Also we checked (Figure 2) that hall microphone ENV_WEB_MIC looks unchanged (meaning that before it was not copying noise from the accelerometers), and also ENV_WE_ALS_MIC looks unchanged (meaning that there is no apparent cross talk between the two microphones now sharing the second NEXUS).

Today around 8:10 CET, the ENV_CEB_MAG{N,W,V} magnetometers have been dispaced from their position on the TCS room terrace to the wall behind the filter cavity tube (figure 2), and their acquisition from the TCSroom to the DET electronic lab. The acquisiton is back to  DET_ADC7674 ...Moni1 (ADC #44) Ch: 8,9,10. The improvement in noise is evident (figure 1) in a wide frequency range.

The North magnetometer is under the "wheeled lockers" on their front side, because the in the rear it was saturated by 50Hz.

This morning, at about 8:00 UTC, we moved one of the CEB magnetometers from the TCSR roof to the corresponding ground level, in the corner under the stairs (see photo). We did this test to understand if the large magnetic noise level detected in the new position of the magnetometers, could be mitigated by moving the probes in a different position. The displaced magnetometer was ENV_CEB_MAG_W and was oriented in the same way of ENV_CEB_MAG_N, left on the TCSR root (btw, we found that the horizontal probes were in the wrong orientation, with the North and West axes exchanged).

Unfortunately, the noise level, at the ground level position, was even worst. In figure 1 the spectra of the two magnetometers are compared: the noise detected on the ground (red curve) is larger respect to the one collected on the initial position (blue curve). We also tried different positions, in particular in the space around the BS, not too close to metallic structures as in the initial one, but no relevant noise reduction was found (figure 2 and 3). There was no time to test other position: we will check possible alternative during next weeks.

At the end we moved again the magnetometer in its initial position, on the TCSR roof, this time with the right orientation...

Yesterday I left the system in FDS meassurement metatron state. In this state the SC PLL is locked but the automation does not control its status.

We can see that the filter cavity and the other PLLs remained locked all the time but this PLL experienced different unlocks (more than 9).

No visible correlation in the ENV channels, but all the sensors are inside EQB1 bench that is closed with the plexiglass.

This morning I went to the NEB to perform the calibration of the current and voltage monitoring signal produced by the high power amplifier driving the large coil. After the calibration I injected, for few minutes, a magnetic field line at 0.5 Hz, Driving Amplitute 4 V, corrensponding to a voltage of about 28.8 V and a current of about 4 A (see fig.1). The line is clearly visible on the magnetometers (fig. 2: blue - injection active, magenta - no injection) together with several harmonics.

It was not possible to perform the same operation at CEB, due to a problem with the high power amplifier (to be further investigated).

A magnetic injection has been performed from 10.40 to 12.15 UTC; we generated a coloured noise  and sent it to the power amplifier driving the WEB Big Coil.

The monitoring channels are ENV_WEB_MAG_COIL_VOLT_MON and ENV_WEB_MAG_COIL_CURR_MON respectively for the voltage and current sent to the Big Coil.

The limits of the power amplifier are +/- 72Vpk and +/- 6Apk, it is set in Voltage drive mode and its transfer function is 7.2 Vout/Vin (with Vin = the voltage sent to the DAC output).

The magnetometers are set in chopper mode.

Today we moved the 3 magnetometers ENV_CEB_MAG_{N,W,V} from their position near the NI to the terrace above TCS room (see picture).

The ADC has been changed from DET_ADC7674 ...Moni1 (ADC #44) Ch: 8,9,10 to CEB_ADC7674_1 TCS_ADC_Moni1 (ADC#56) Ch: 12,13,14

TolmFrameBuilders

All the TolmFrameBuilder servers have been restarted with the keyword:  REALTIME_FRONTEND   all 90

Operations performed  between 2022-10-11-04h46m31-UTC and 2022-10-11-04h46m38-UTC .

As consequence  there is 13s of missing data between GPS1349498809.8 (2022-10-11-04h46m32-UTC) and GPS1349498822.8((2022-10-11-04h46m32-UTC)

magnetic noise injection system

Dedicated channels for magnetic noise injection in the CEB, NEB and WEB buildings are now provided   by the ENVnoise server, respectively NOISE_MAG_CEB, NOISE_MAG_NEB and NOISE_MAG_WEB

These channels are sent

• for the NOISE_MAG_CEB channel to DAC1955_SN09 (SIB2_DAC_SBE0) channel 6 by the SIB2_SBE server
• for the NOISE_MAG_NEB channel to DAC1955_SN101 (SNEB_DAC_SBE0) channel 6 by the  SNEB_SBE server
• for the NOISE_MAG_WEB channel to DAC1955_SN39 (SWEB_DAC_SBE0) channel 6 by the SWEB_SBE server

In operation since 2022-10-11-05h03m02-UTC

Today, after some fine tuning, we generated a white noise (from 0 to 5 kHz) and sent it to the power amplifier driving the WEB Big Coil. The levels have been set so as not to saturate the amplifier or the WEB magnetometers.

Signals are good from 10:00 to 11:30 UTC (September 30th).

The monitoring channels are ENV_WEB_MAG_COIL_VOLT_MON and ENV_WEB_MAG_COIL_CURR_MON respectively for the voltage and current sent to the Big Coil.

The limits of the power amplifier are +/- 72Vpk and +/- 6Apk, it is set in Voltage drive mode and its transfer function is 7.2 Vout/Vin (with Vin = the voltage sent to the DAC output).

Attached is the transfer function between the Big Coil current monitor and the three magnetometers in the WEB hall. Coherence is (very) good from less than 1Hz to a few kHz.

If the calibration value of the magnetometers is applied, the transfer function becomes reasonably flat (the magnetometers are currently not in Chopper mode, which would increase the bandwidth even more)

Please note that, having the Big Coil a resistance of 7.32 Ohm that is numerically very near to the power amplifier gain (7.2), sending 1V to the amplifier means to send 1A to the coil (at least in DC and below ~10Hz, where the inductive part is not yet dominant). Because the maximum current capability of the power amplifier is 6Apk, the DAC voltage need to stay below 6V for frequencies below ~ 10 Hz.

Yesterday, during the maintenance, we installed the Large Coil Interface in the CEB terrace. The electronics was placed inside the small rack (see photo) close to the coil.

No test was performed since we faced some throubles with the mains, solved only in late morning, so we prefer to not switch on the High Power Amplifier during the commissioning activity.

In the meantime we completed the installation of the same system in WEB (the network connection was missed), and tested the new servers (LargeCoil_CEB and LargeCoil_WEB) to drive the Large Coil Interface (both in WEB and CEB, by switching on/off the safety lamp).

We left both the Interfaces (WEB and CEB) switched on, with the corrensponding servers active. The HV amplifier at WEB was set in Voltage Mode, while the one in CEB was set in Current Mode. Both are switched off.

This morning I performed some test with the Large Coil installed in WEB, using the Large Coil Interface for the driving. Since the network connection is still missing I used a floating cable to connect the Interface to the network in order to remotely switch on and off the High Power Amplifier. After a first check to verify that the problem of main breaker was really solved, I injected some lines with different frequencies and amplitudes (see the summary for details); during the test the Amplifier was set in Voltage Mode. The system works fine. In figure 1 the rms of the driving signal, the current and voltage monitors of the Power Amplifier and the WEB magnetometers are very similar in shape. In figure 2 the driving signal, the voltage and the current monitors are shown for a small period for the 28 Hz driving signal: the red curves represent the voltage and current after the removal of the electronic offset (the Voltage Gain of the amplifier is 7.2 V/V). In figure 3 there are the same signals for the 5 Hz driving. Finally, in figure 4, the spectra of all the signals, during the two main injections, are shown.

After the test the Power Amplifier was remotely switched off and the network floating cable was removed. I left the Large Coil Interface switched on.

Data from weather station were not available since August 5 at 1:30 UTC. This afternoon we checked the console status and it seemed to be ok. Then we tried to reset the console by switching it off and on. After this operation, the data were correctly received by the server, nevertheless it is not clear why the console was stuck. We also cleared all the alarms from the console (after the reset the high temperature alarm was on).

We found a way to overcome the tripping of the main breaker after the switch off of the ac power. It consists in shorting two pins of the rear connector of the High-Power Amplifier (as suggested by the manual…). The new arrangement of the rear connector was verified on the amplifier placed in CEB this morning, and it worked perfectly.

In this way the installation of all the Large Coil Driving System can proceed as planned, since the remote switch on/switch off capability provided by the Large Coil Interface, can be fully exploited.

This afternoon we installed the Large Coil Interface in the WEB. We placed both the Interface and the High Power Amplifier in the small rack close to the left entrance to the experimental hall (see photo). The system is now fully cabled, except for the network connection, that is still pending. For the test we used a temporary floating cable that was disconnected at the end of the work.

The Interface provides: a) a remotely switchable (on-off) electrical socket used to power the Amplifier; b) a remotely switchable (on-off) 12 V power supply to turn on the safety lamp that signals the magnetic field injection; c) a suitable conditioning for the signals from/to the DAQ, in particular a gain of 0.5 for Voltage Monitoring signal, a gain of 2 for the Driving Signal, no conditioning (except for the single ended to differential conversion) for the Current Monitoring signal.

During the test we realized that, while the switch on of the High Power Amplifier works fine, after a switch off the main breaker of the Amplifier finally trips definitely into the off position. This means that a direct intervention is needed to restore the system after each switch off.

Apart from this problem, all the other function works fine: the safety lamp switches on and off regurarly and the signal conditioning is ok. We injected a constant voltage to check the gain of the monitoring signals and then a line (amp.: 0.5 V corresponding to an output voltage of 3.6 V, freq.: 17.17 Hz). The signal is clearly visible in the magnetometers (fig. 1 and 2). During the test the Amplifier was operated in voltage mode.

Please note that the rack is very close to a marker of the NNC accelerometer network: the probe was not in its place during the installation, but we suggest to not fix it again on the floor at least for the next two weeks, since we need to operate on the rack for further test.

Yesterday, around 16:25 the temperature probe on the north wall of the CEB (close to the TCSR) stuck. This afternoon, around 14:00, we changed the probe. Since this probe is placed on the same PCB together with a humidity and a pressure probe, the signals affected by this change are: ENV_CEB_N_TE, ENV_CEB_N_HU and ENV_CEB_N_PRES. After the replacement the temperature signal came back to standard values (see plot).

the attached plot compares spectra of the CEB guralp's 3 channels when the sensor is read by the centaur data logger (left, May 8 21:00 to midnight) and when it is read by the Virgo DAQ and conditioning electronics (right, May 1, around midnight). In both conditions, the noise rise below 100mHz in all three channels (less pronounced in the vertical channel) is similar. The centaur sensitivity was set to its maximum value (i.e. 1 V full range) so to minimize the ADC noise. Both periods correspond to low wind speed (<10 km/h).  We conclude that the noise rise below 100mHz is not due to electronic noise.

This morning, around 8:58 LT the large coil amplifier in CEB was switched off.