Artem, Gabriele, Sheila, Louis

Plots and Jupyter notebook with these results are also available here.

The offloading scheme, in terms of actuation on different stages (UIM, PUM, TST), is different for LHO and LLO. We suspect that this could be the reason for apparent ESD noise coupling resulting in excess Low-frequency noise at LHO (see 74315).

Here I present a comparison of external disturbance (CAL-DELTAL_CTRL_UIM/PUM/TST_DBL_DQ) and DARM error signal (OMC-DCPD-SUM_OUT_DQ) for LHO vs LLO. What we see is that external disturbance is very similar for both sites, while error signal is notably different, i.e. there are indeed significant differences in offloading scheme. There will be further discussion from Louis and my plots here are supporting material for that.