J. Kissel

Picking up where Borja left off, I've measured the charge H1 SUS ETMY test mass / reaction mass system. Today's measurement is made in hopes of seeing if the ion pump is the smoking gun causing all the charging noise. Driving quadrant-by-quadrant, and using the optical lever's Pitch and Yaw signals as my response, with a 0.02 [Hz] binWidth, with 5 (instead of 3) ensuring I had a coherence of at least 0.75 (i.e. an relative amplitude uncertainty of less than sqrt((1 - 0.75)/2*5*0.75) = 18%), and taking 5 bias data points (instead of 4), I arrive at the following effective bias voltages:
      P [V]     Y [V]
UL   104       149
LL   129       72
UR   110       13.6
LR   104       117
For some reason Pitch had much better SNR for the same drive amplitude, but given that I accounted for the coherence, both pitch and yaw are to be believed. I'm not sure, however, why pitch shows such a uniform charging distribution, where yaw reports the charge is spread unevenly.

I'll gather more measurements and plot the results against Borja's previous measurements tomorrow. Since we expect this to evolve with time, there's not to much point in putting it up against the ion pump closed results just yet.

I've got some clean up functions and scripts to do, bear with me while I catch up to what Borja had assembled. I could have ask him for his analysis scripts, but it was easier just to write my own, given that the analysis is so simple. Still no automation of this measurement, and given the first-day-back barrage of Q&A, it took me ~4 hours to complete the measurement. I expect this will go faster once I gather my stride. As usual, it's a toss up between "let's just get the answer now" and "take the time to debug the automation." I elected for the former.