Duty Cycle in O3 and O4 winters vs microseismic ground motion

Preeti, Gaby, Tabata, Debasmita

Summary:

We calculated the duty-cycle of L1 and H1 in O3, O4a and O4b winters (Nov, Dec, and Jan) on each day and plotted with the median of microseismic ground motion in 0.1-0.3 Hz and 0.3-1.0 Hz. The duty-cycle was modified by removing earthquake times (ground motion in the 0.03-0.1 Hz band above 150 nm/sec) from lock duration and day duration.

Conclusion:

• We found the evidence of linear correlation between microseismic ground motion and duty-cycle; except for Hanford O3 and O4a (2023) winters. For Hanford, useismic ground motion affected the duty-cycle in O4b winter (2024-25) only (see figure).
• In L1 O4a winter (2023-24) plot, zero duty-cycles at lower ground motion disappeared in the next winter, which seems to be resolved with the changes in ETM and CRYO BAFFLE during Jan 2024 commissioning break (LIGO-G2400537).
• Negative value of the Pearson coefficients indicate negative linear correlation between them (see the attached table and plots).