As mentioned in LHO:74264, Sheila and I have been taking a closer look at the DARM loop and our ability to model the PUM crossover in particular in response to LHO:73937. I'm attaching a plot of the DARM OLG with the pyDARM model (blue trace), OLG measurements taken as part of the weekly calibration measurement suite (orange dots), and Sheila's measurements from Friday (LHO:74264) with the Y2L and P2L gains nominal (green circles) and with the Y2L and P2L gains reduced by a factor of two (red crosses).

There's a few interesting things going on that I'll have to elaborate on in a future alog. Briefly, the model clearly doesn't match any of our measurements below about 20Hz (zoomed out version also attached). 

More plots of just the PUM and UIM crossovers are in progress.





Relevant Links:

- Sheila takes OLG measurements with different Y2L and P2L gains (LHO:74264)
- Sheila attempts taking PUM crossover measurements at the L2 LOCK band (LHO:74226)
- Gabriele finds nonlinear high frequency noise coupling in DARM and suggests offloading ETMX L3 (LHO:73937)