Plots showing the vertex finding efficiency vs. the transverse position of the vertex. The first two plots show the number of counts (on two different scales of transverse position) total (the red histograms labeled "all") and the the number of counts for which the correct vertex was found (the blue histograms labeled "good"). The third plot on the page shows the efficiency ("good" divided by "all") for finding the vertex. The calculations are done with a combination of the pisa and pisorp which are part of the Phenix detector's simulation package.