As mentioned above, an orientation angle phi is calculated for each hit found. We also assume the track is primary, and trivially obtain . From this, we use an empirical formula to extract the crossing angle .
Figure 29: Crossing angle as calculated by hitfinder based on cluster shape is compared with the true crossing angle generated.
We find reasonable correspondance between the calculated crossing angle and the true one, on average, as shown in Figure 29 for a Au+Au event. However, the dispersion about this average is large. The crossing angle found by the cluster/hitfinder may be useful to the tracking software in some cases, but clearly a better resolution in the determination of would be desirable. Our understanding of the relationship between the hit pattern shape and the crossing angles is obviously incomplete, and this issue remains a topic for further study.