During yesterday evening shift (ITF locked in Low noise 2) we performed this set of magnetic injections (details in the attached log file):
- small coil at SDB1 tower base (inside detection lab): sweeps between 20 Hz and 1000 Hz, three orientations of the coil. See pictures 1,2,3.
- large coil CEB: two 9V sweeps from 10 Hz to 1000Hz. The first sweep with periodicity of 1800s but we could see no effect in hrec. The second sweep was launched overnight and had a periodicity of 14400s.
Figure 4 shows an overview of our injections.
Figure 5: injecting with the small coil we could see effects in DARM up to ~350Hz, nothing above.
Figure 6: the hrec response to the injected field is not smooth but it sorts of resonate at some frequencies, approximately: 31 (strong), 193, 111, 119, 157 (strong), 164, 169, 176 Hz (need to check if they correspond to modes of SDB1 bench). Also, as can be observed in Figure 7, sidebands are excited around some of these frequecies.
We performed sweep injections with the large coil within the same lock in order to check if the large coil injecting in the (more) far field was exciting similar hrec frequency modes or not.
Figure 7: The first fastest sweep (1800s long) was not able to excite much, just the 157Hz mode excitation is visible there too.
Figures 8 to 12: we then injected a slower sweep (14400s long) in order to be able to "deposit" more energy. Indeed this time some exitation of DARM is visible. The excitation is clearly not uniform, but some DARM modes resonate. Teh most evident ones are around 48Hz and around 157Hz.