More Stripline Testing

The amplitudes of the reference cavity REFC1 and the sum signals from the stripline BPMs are well correlated but show signs of non-linearity in places. The outliers are probably in the wrong timing window because they appear in all the striplines at the same places. There is clear non-linearity in BPM MQD14X which has a large signal.

Regression

Including the stripline BPMs in a regression of the BPMs give the following result. The jitter subtraction is clearly not total as can be seen by the correlation between rms and residual values. This should improve with calibration and tuning.

Jitter Subtraction Preliminary

As a preliminary test of future jitter subtracted calibrations, the first 8 stripline BPMs were used to subtract the jitter from the downstream cavity BPMs that are not on movers. The result shows the jitter is reduced to about 1 μm. This is likely to improve when the BPMs are tuned and when their raw signals are being used instead of their position measurements but even at this level, it should improve the accuracy of the calibrations in this region.