Haocun, Nutsinee, Robert

We took a quick look at acoustic noise on H1:SQZ-OPO_SERVO_CTRL_OUT_DQ by exciting optics and the HAM6 chamber. Manual excitation suggested that, roughly speaking, the peaks in the 300 to 400 Hz area were associated with optic mounts on ISCT6, and the peaks in the 600, 800 and 1000 Hz region were associated with vibrational excitation of HAM6, such as the blue piers. This is also what the coherence in the attached plot shows. The HAM6-associated noise is coherent with the GS13s and is at the ISI suspension resonance frequencies (blade springs and wires) that we damped to reduce acoustic coupling to DARM.