With T6 trigger, most event have tracks as well as passing good electron cuts. Here is 1M ev run 1769 with positron and central dp cuts cut. However, no software coincidence cut was applied. VZ strip is still more spreaded. And it appears there is no clear sieve holes. Could try more by varying cuts.
Figure 1: * Left top: 2D hit map on VDC * Right Top: track angle at target (tg_th:th_ph) * Left Bottom: momentun deviation (tg_dp) * Right Bottom: VZ vs tg_ph correlation.