This afternoon I switched on the EFM chassis for the first time since Fil fixed the gain.
The Y axis, which used to have high noise at high frequency, is now very quiet, see first screenshot. I'm not sure why this is the case.
I also had a look at the time series over 4 hours after turning on the EFM, see second screenshot, the noisy parts are when the ETMX ESD actuators are used while the commissioning team acquire lock. This noise is seen in both X and Y axes.
Hi Georgia, I am not quite sure I follow all of this, but I am interested. I see a few plausible explanations relating to changing the machine states that may explain a shift in the noise spectrum, but I could be missing your point. At this point, are you thinking there could be a malfunction in the electronics chain somewhere? I can dig into this further tomorrow and generate zero field noise spectrum if you find it useful. Please let me know if there’s anything I should be working on relating to this issue.
Hi Rich,
Sorry there was a typo in my alog which might have caused confusion: I meant to say turned on the EFM, not turned the EFM.
I don't understand why the Y axis spectrum has quieted down, perhaps we fixed an electronics problem we didn't know we had? Or something with high Q has finally rung down? Since it is still sensitive to electric fields, I'm not sure there is an issue.