Attached are some DARM comparison plots from different times over the last several months of 2022 (all without squeezing).  Making these plots required some changes to the noise budget code which Chris Wipf helped with, (see git issues 54  and 51 about using different channels for DARM at different times, and issue 53 about applying the corrections for the new DCPD whitening chassis to CAL-DELTAL type channels with help from pyDARM and Jeff and Louis).  This was more work than I expected to make these plots, but these features are also needed for us to use the noise budget as a noise budget, so it's a worthwhile effort. 

The first two attachments are a comparison of the DARM spectrum and cumulative range integrand before and after the septum removal.  The after time is with the calibration checked as in alog 65879.  The reduction in peaks below 100Hz gave us ~12Mpc of BNS range according to this, there is slightly worse noise from 100-150Hz in the time I choose after the septum removal, this is probably unrelated to the septum removal but does seem to be a consistent change.  The worse noise above a few kHz is realted to the thermal state at the time I choose and is not consistent between differnt times.  

The next two attachments (spectra and cumulative range intergrand) show the difference before and after Robert added alligator clips to the ISC Common Chassis at EX, times are from Georgia's comment on that alog 66010. We gained 5Mpc due to the improvement between 30-50Hz that this made.  Since this time the grounding has been improved further,  (66469) and we plan to continue some investigations; the point of this plot is to show that indeed this grounding issue was limting our range and these steps have improved things somewhat. 

The next set (spectra and cumulative range integrand)  is a comparison of right before the septum removal to the end of the year, so this includes the septum, grounding changes, several changes to ASC and damping loops, and the power increase.  So, this shows that we have made a good deal of progress over the last several months, with 25Mpc of range improvement below 100 Hz and 5 Mpc of range lost from 100-150Hz.  

The last pair show a comparison of the end of 2022 to O3B without squeezing, spectra and cumulative range integrand.  The sensitivty is broadly improved above 40Hz, and worse below 40Hz.  Indeed the overall range is improved, improving the noise below 40Hz could give us another 10Mpc.