Geant4 User's Guide for Application Developers - Geant4 - CERN

User ActionsG4UserSteppingActionExample 6.8. G4UserSteppingAction//---------------------------------------------------------------//// G4UserSteppingAction.hh//// Description:// This class represents actions taken place by the user at each// end of stepping.////---------------------------------------------------------------///////////////////////////class G4UserSteppingAction///////////////////////////{//--------public://--------// Constructor and destructorG4UserSteppingAction(){}virtual ~G4UserSteppingAction(){}// Member functionsvirtual void UserSteppingAction(const G4Step*){}//-----------protected://-----------// Member dataG4SteppingManager* fpSteppingManager;};6.2.2. Killing Tracks in User Actions and Energy ConservationIn either of user action classes described in the previous section, the user can implement an unnatural/unphysicalaction. A typical example is to kill a track, which is under the simulation, in the user stepping action. In this casethe user have to be cautious of the total energy conservation. The user stepping action itself does not take care theenergy or any physics quantity associated with the killed track. Therefore if the user want to keep the total energyof an event in this case, the lost track energy need to be recorded by the user.The same is true for user stacking or tracking actions. If the user has killed a track in these actions the all physicsinformation associated with it would be lost and, for example, the total energy conservation be broken.If the user wants the Geant4 kernel to take care the total energy conservation automatically when he/she haskilled artificially a track, the user has to use a killer process. For example if the user uses G4UserLimits andG4UserSpecialCuts process, energy of the killed track is added to the total energy deposit.6.3. User Information ClassesAdditional user information can be associated with various Geant4 classes. There are basically two ways for theuser to do this:• derive concrete classes from base classes used in Geant4. These are classes for run, hit, digit, trajectory and trajectorypoint, which are discussed in Section 6.2 for G4Run, Section 4.4 for G4VHit, Section 4.5 for G4VDigit,and Section 5.1.6 for G4VTrajectory and G4VTrajectoryPoint• create concrete classes from provided abstract base classes and associate them with classes used in Geant4.Geant4 classes which can accommodate user information classes are G4Event, G4Track, G4PrimaryVertex,G4PrimaryParticle and G4Region. These classes are discussed here.202