In the tracking step (ZTCALO), SGV determines which calorimeters the
particles will hit. The user can choose (with the steering card CHSHOW)
if showers of charged particles should also be considered, or only from
neutral ones. For neutral particles, this simply implies finding the
intersection of a straight line with planes or cylinders, for charged particles
the helical track must be calculated as for the tracking detectors.
The routine ZTCALO does this calculation, and returns a list of calorimeters
intersected, ordered by the distance between production-point
and impact-point. The output from ZTCALO should be sufficient input for
any simulation of calorimeter response.
