I was trying to see how different the correlation between the vertex from the VPD and from Minuit  for low luminosity and high luminosity ,but the unfortunately the calibrated runs provided from the TOF group is only for few runs with  a limited range of high BBC coincidence rate:

Here is the zVPD vs zTPC/Minuit   correlation :

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The sort of Horizontal band is pile-up (I was hoping there would be a distinction between the two ,one would be HighLum and the other LowLum ,but looks like it is not low enough) .

Below is the number of vertices found for the "sort-of-LowLum" and high Lum: