Looking at all measurements (taken with a straight moving wire) of the derivative of the horizontal field integral (vertical kick) with respect to x (a skew quadrupole like term) there seems to be no good correlation with the observed changes of the vertical beamsize. Previously, looking at only one such set of data (for minimum gap at sector 11), it appeared as if the shape and the amplitude of this skew quadrupole like term was consistent with the beam size variation. For the EPU in sector 4 and for other gaps this was not true anymore. The first plot shows a comparison of the field integral derivative for the EPUs in sector 4 and 11 at minimum gap (14 mm). The second plot summarizes the measurements for all gaps for sectors 4 (top) and 11 (bottom).
Conclusion: The initial agreement of the amplitude of the variation of the derivative of the horizontal field integral with the EPU phase for minimum gap in sector 11 and the amplitude of the beamsize variation of the beam seemed to be coincidental.
