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Environmental Monitoring (Environmental Monitoring)
fiori, paoletti, tringali - 15:26 Tuesday 24 September 2024 (65201) Print this report
noise measurements at WEB

This morning during maintenance time we performed some measurements inside the WEB hall which are useful for the IME mitigation projects.

We measured magnetic field in proximity of the power line cable tray (North wall of the experiental hall). We used one Bartington magnetometer, named ENV_WE_MAG_TEST_X,Y,Z. See Picture 1. Details in the attached log file.  We first made and huddle test with the Metronix magnetometers to verify the calibration of the sensor. Figure 1 compares magnetic spectra of this magnetometer when close to the cable tray, the metronix magnetometers, and the magnetometer close to the WE tower. There are evident sidebands at +-6 Hz of 50Hz and odd harmonics. This is different from the situation at NEB, also shown in the same Figure: the NEB magnetometers signals are characterized by one 13Hz peak and +-13 Hz sidebands of the 50Hz and harmonics (we know that these are associated to the 2400N UPS, https://logbook.virgo-gw.eu/virgo/?r=30963). The origin of these 6Hz sidebands at WEB has to be investigated.

With the purpose of characterizing the acoustic and seismic noise emission of the racks in the WEB hall, we moved one accelerometer (ENV_WEB_ACC_RACKS) and one microphone (ENV_WEB_MIC_RACKS) sequentially onto (and in front of) each module with cooling fans (10 minutes in each location). See the attached pictures and details in the attached log file. Figure 2 shows spectra during the measurement at the Nikhef SWEB module in rack5.

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Paoletti, Fiori, Tringali, D'Andrea - 10:04 Wednesday 25 September 2024 (65205) Print this report

We made a survey along the tubes in the last 1km arm reaching the terminal buildings. To be reminded, these tunnels are powered with the NEB and WEB IPS mains line, likewise the first slice in the beginning is powered by the CEB IPS, while the intermediate tunnels are conected to the 1500N and 1500W IPS mains line.

We probably found the device generating the +/- 6Hz sidebands of the mains in the WEB magnetometers: it could be a small (2 kVA) UPS installed on December 28, 2023 at 2100m west arm (900m from WEB). This UPS is only connected to the " T " IPS line, unlike other UPSs (2400m) which are three-phase and produce the well known 13 Hz bump with its associated 50 Hz sidebands.

In the attached figure, the top row shows the magnetometers in the experimental room, while the bottom row shows the small triaxial magnetometers near the towers (vacuum chambers). Signals of a large (~8 kVA) three-phase UPS at NEB (blue trace), and those of the small single-phase 2 kVA UPS at WEB (red trace) are clearly visible in the upper left pane.

We will schedule a shutdown to verify this hypothesis.

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fiori, quemener - 12:58 Tuesday 08 October 2024 (65285) Print this report

Today during maintenance we positioned one Bartington 3D magnetometer in the WEB SAS close to the cable trays, at the same height as the bottom tray about 50cm away from the tray. Pictures of the installation are attached. The probe names are:

  • ENV_WE_MAG_TEST_X - oriented towards East 
  • ENV_WE_MAG_TEST_Y - downwards
  • ENV_WE_MAG_TEST_Z - paralllel to cable tray going North

The probes started taking data at about 9:15 UTC. At 9:48 UTC we switched off the lights of the hall. 

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fiori, tringali, quemener, paoletti, d'andrea - 12:58 Wednesday 09 October 2024 (65290) Print this report

Yesterday afternoon we returned to WEB for the scheduled shift on scattered light, which could not take place because of ITF problems.

We profited to move the Bartignton magnetometer in a new location: we placed it on the floor of the SAS, approximately in the center and we kept the same orientation of the axies.  The attached pictures show the installation. The good data are Oct 8 from 16:35 to 17:10 UTC. Same channel names. In this location the magnetometer is about the same distance from the cable trays in the SAS as the Metronix magnetometers are from the cable trays in the hall, while the Bartington is closer to the chillers: see the map in the third attachement. The map provided by Massimo shows in red  the path of electrical cables.
 

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