Introduction
Eric suggested that looking at the POCA distance (in sigma) from ACD tiles should give different distributions for tiles that are hit than for those that have no hit. Basically, this is saying that you expect tiles without hits to have track POCA that are more than 1 sigma from the tile active boundary. On the other hand hit tiles are expected to have POCA with negative sigma (distances inside the active tile). The cross-over from dominantly positive sigma POCAe to negative sigma should be a sharp feature which is present in the data and MC.
Monte Carlo
Generate 10^5 CrProton, I grab the projected and propagated track covariance projected onto the POCA plane.
Hit == mipsPmtA() < 0.001 and mipsPmtB() < 0.001