**** 401 Hz peak investigation @ INJ turbo pump - Dec 11, 2025  ****

DAC channel: ENV_NOISE_CEB_DetTerrace
monitor probe current: ENV_PROBE_CURR_MON

We regulate the amplitude of injected seismic line (magnetic) in order to match 
the height of the 401 Hz peak in the IB accelerometer (IB magnetometer)


Injection with small shaker

10:21:52 UTC, seismic line  @ 405 Hz, ampl= 0.4 (nothing seen in hrec…)
10:32:20 UTC, seismic line  @ 410 Hz, ampl= 0.4 
10:34:12 UTC, seismic line  @ 410 Hz, ampl= 0.8
10:35:42 UTC, seismic line  @ 410 Hz, ampl= 1.2 
10:39:54 UTC, seismic line  @ 410 Hz, ampl= 1.6 (seen a large peak in hrec)
10:46:11 UTC, seismic line  @ 390 Hz, ampl= 1.6 
10:48:59 UTC, seismic line  @ 390 Hz, ampl= 0.4 
10:51:08 UTC, seismic line  @ 390 Hz, ampl= 0.2 (same)
10:57:38 UTC, seismic line  @ 395 Hz, ampl= 0.2 
10:59:51 UTC, seismic line  @ 395 Hz, ampl= 0.4 (same)
stopped 11:08:37 UTC
======================================================================

Injection with small coil
coil axis along W-arm
11:18:45 UTC, magnetic line @ 395 Hz, ampl= 1.0 (nothing evident)
11:24:21 UTC, magnetic line @ 390 Hz, ampl= 0.8 same
11:29:35 UTC, magnetic line @ 410 Hz, ampl= 0.8 same
11:34:43 UTC, magnetic line @ 405 Hz, ampl= 0.8 same
fino a 11:40:30 UTC

coil axis along N-arm
11:40:52 UTC, magnetic line @ 405 Hz, ampl= 0.8 (a peak grows in Hrec but after a while …)
until 11:49:00
coil axis vertical
11:49:40 UTC, magnetic line @ 405 Hz, ampl= 0.8 (also here we see the peak in hrec, it is about half the amplitude of the 401 Hz peak)
11:55:07 UTC, magnetic line @ 410 Hz, ampl= 0.8 (no peak!)
stopped 12:00:20 UTC