Back on December 05th 2024 we had a really large earthquake come through from northern California. This large nearby earthquake reminded Sheila of an old script that checked to see if the test masses had acquired any charge from hitting an earthquake stop during an earthquake. This script had been used to discover hysteresis after particularly large earthquakes in 2017 (37799) and in 2020 (55880). We decided it would be a good idea to check for this earthquake, so we wrote a quick python script move_all_quads_pitch.py that changed the OPTICALIGN pitch for 110 seconds before moving everything back. I then took the matlab script from 2020, check_hysteresis_2020.m and edited the times and channels so that it would grab minute trends for the DAMP_IN and COILOUTF_OUT channels for the week leading up to the earthquake, and then grabbed raw trends for those same channels after the earthquake and during the period of time where we had moved the OPTICALIGN pitch. I plotted the OSEM readings (DAMP_IN) versus the applied force (COILOUTF_OUT) for both times against each other for each test mass and got this plot. Looking at this in addition to the pitch drift plots from the summary pages(ITMX, ITMY, ETMX, ETMY), it doesn't look like any of the test masses encountered any hysteresis as a result of any earthquake stop hits.

All these scripts and results can be found in userapps/sus/h1/scripts/check_hysteresis_after_EQ and have been committed to svn.