Shower-track association
Also of importance for the correct analysis of the data
from the calorimeters is the question of shower-track association.
Whenever a charged track extrapolates close to a calorimetric
shower, the question arises whether the shower is induced
by the charged particle, or by a neutral particle that happens
to be close-by, or by both the track and a neutral. This effect
is simulated by SGV by the routine ZAUCSH. This routine is
called by ZAUSHO, if the steering-card MIN_SEP_CLU_TRK is set
to a non-zero value. The value of this card is the minimal
distance (in cm) between the shower start-point and the track-extrapolation
at which the track will be possible to separate from the shower.
The routine loops all tracks and all clusters, and compares the
two positions, and that way decides if the track will be associated
to the cluster, or not. Hence, both mistakes are possible: a track
might be associated to a cluster it did not induce, or a track might
not be associated to a cluster it d i d induce.