Tonight we made a series of noise injections to the SDB1 bench. First we did low-frequency sine waves into the Z and X directions, then we made broadband noise injections into the angular degrees of freedom.
The Z-direction excitation produced a clear scattering shelf, see Figure 1. This is similar to what we observed when SDB2 was similarly excited last week.
The X-direction excitation caused the B5 quadrants to become misaligned, and this subsequently caused the BS to become misaligned. See Figure 2
The most interesting results were from the broadband noise injections to SDB1 LC TX, TY, and TZ. Romain constructed a few filters that injected a lot of noise above 100Hz. This excited many features in the DARM spectrum, for example the line at 190Hz that Paolo observed to breath with the alignment of the bench, and many other features. See Figures 3, 4, and 5. There's a lot of features to explore.
Romain also made injections to SDB1 LC TX and TY with white noise, to see if we could increase the DARM noise below 100Hz. In fact we could, and in a smooth way. See Figures 6 and 7.
We also went to the detection lab and waved an IR card in front of the B1s1 beam on EDB. There was no scattering noise in DARM, so probably it's ok for this beam to come out of the vacuum. We made some tap tests of EDB and SDB2, there is a ~450Hz line that can be excited when we tap on the SDB2 doors, see Figure 8. Also pushing on the EDB side of the SDB2 tower causes scattering shelves, see Figure 9 -- this could be moving the whole bench and causing the same scattering that we see when we make a low-frequency Z injection.
The switch to BS low noise is working, but Paolo found the marionette reallocation needs to be tuned, so we have commented the lines in metatron that switch the BS coils to low noise.
