All sensitive detectors are represented internally by a positive integer.
Although this is not a requirement by Geant4 (which assigns a name to the sensitive detectors), having an integer make it easier to store hits in a flat tree with a single integer variable representing the detector. This then allows:
T->Draw("hit.y:hit.x","hit.pid < 20")
The full listing of detector numbers can be obtained with a macro
build/remoll macros/printgeometry.mac
The number in square brackets at the end of the line indicates the detector number for those volumes. If there is no number in square brackets, that means that the volume does not have a sensitive detector associated with it.
To connect the numbers to more human readable detector names it is also possible to use convenient aliases in the output tree:
T->Draw("hit.y:hit.x","hit.pid == dets.lv.logicDScoll_5")
T->Draw("hit.y:hit.x","hit.pid == dets.sd.pionLuciteDet")
In the first case (dets.lv
) the logical volume name is used. In the second
case (dets.sd
) the sensitive detector name is used.