As for the HSTSs, I took a spectra of PR3 from Monday. The isolation and damping loops of the ISI were closed (isolation level 3), as well as the damping loops of the suspension. The chamber was still under vacuum. Status of HEPI needs to be double checked.
The attached plot compares the spectra of LHO and LLO PR3, in a similar configuration (ISI isolated, SUS damped), for the 3 levels (M1 M2 and M3) and every degree of freedom.
Looking at the plots, we can see that LLO get more isolation at each level, even though we are using the same damping filters. That said, Jeff discovered that the suspension medm gains are set to different values, (higher values at LLO) which would explain why the resonnances of the suspension are more damped there. Other than this, spectra is very close to sensor noise. The larger signal between 0.1Hz and 1Hz is highly due to ground motion (I quickly took a spectra of the streckeisen sitting next to HAM2 chamber, which shows the same shape around 0.1Hz) More details to come next week.
Attached is the same document with the individual osems included
For acceptance review, attached is a phase 3b comparison of PR3 spectra damping on vs damping off. HAM2 ISI was in its isolated state, and HEPI was running under position control during the measurement.