We set up one gound current monitor, we named ENV_CEB_GROUND_CURR_MON which is connected in DAQ room, ADC 7674 n.46, ch.11.

The probe is one Tektronix A622 clamp, with max range set 0-10A, 100mV/A.

Since around 11 UTC the probe is clamped on the two grounding cables connecting the ENEL and UPS electrical panels located in CEB in front of the INJ cryotrap. See Figure 1. The measured current is about +/- 7A. 

Before choosing this final location we performed some tests.

We first checked that the clamp measurement was not influenced by the current flow in the nearby electrical cables. For doing this we positioned the probe onto the cable tray and oriented it in the 3 othogonal directions (the measured  current was around +/- 0.07 A for all three directions). See Figure 2. We also positioned the clamp about 1m away from the cable tray (the measured current was +/- 0.047 A).

We also performed a measurement on some of the grounding cables connected to the copper grounding collector bar (see Figure 3), peak values are reported in the attached txt file. We noticed that for all grounding cable the signal has the same spectral shape, but different intensity. Figure 4 compares ASDs measured at some positions. Figure 5 shows trend data.