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Runs with Cherenkov veto

Clearly, the philosophy of the matching of non-identified $dN/d\eta$ can be implemented only for the runs with no Cherenkov veto. Statistics for kaons in pion runs is too low for meaningful analysis of physics as a function of centrality. One has to learn how to determine centrality of runs with the Cherenkov veto in the trigger. The way I do it is the following.

I link the T0 thresholds for the kaon run with chosen T0 thresholds in the nearby pion run by requiring bin-by-bin (in T0 bins) correlation of Si between the two runs. Once centrality of the pion run is known (by varying the centrality to optimize the correlation between spectrometer and Si $dN/d\eta$, as described in the previous section), the link to the pion run is provided by Si. Now I vary centrality of the kaon run ${c}_{K}$, thus vary T0 bin boundaries and optimize the correlation of Si with respect to Si - between the kaon and pion runs. The kaon run centrality that maximizes the correlation is accepted. In other words, the kaon and pion samples are normalized to each other using the Si; samples of identical Si multiplicity are

1. selected by proper choice of T0 thresholds
2. normalized using identical values of trigger centrality.