Figure 8

Top: distribution of the horizontal interaction vertex coordinate as a function of time during the length-scale calibration run. The structure visible in the timestamp region between $\simeq$100s and $\simeq$600s corresponds to the beams being moved in five steps of 28$\mu$m each.
Bottom: average horizontal vertex coordinate as a function of the nominal horizontal beam displacement in the length-scale calibration run, with superimposed linear fit (solid red line).