I took some sqz and no sqz quiet times from yesterday to try and make a plot of the excess noise agaion as in this entry. As Vicky thinks this correlated (non-quantum) noise is getting better.

For the first image I compared calibrated DARM from  this week with the same measurement from March and from 04a.

Grey is from 04a, purple is from previous slide with March data, yellow and green are from this week.

What we can get from this plot is that this non-quantum noise is different from lock to lock and we are not sure why.

Between 80 and 190 Hz the excess noise seems to now be better relative to March and 04a.

But the fact the noise without squeezing changes so much in a week is confusing.

In the second plot I have just compared three no squeeze quiet times from this week and it easier to see that the noise is not consistent below 200Hz.