G4Event represents an event. An object of this class
contains all inputs and outputs of the simulated event. This class
object is constructed in G4RunManager and sent to
G4EventManager. The event currently being processed can be
obtained via the
getCurrentEvent() method of
A G4Event object has four major types of information. Get methods for this information are available in G4Event.
Details are given in Section 3.6.
Trajectories are stored in G4TrajectoryContainer class objects and the pointer to this container is stored in G4Event. The contents of a trajectory are given in Section 5.1.6.
Collections of hits generated by sensitive detectors are kept in G4HCofThisEvent class object and the pointer to this container class object is stored in G4Event. See Section 4.4 for the details.
Collections of digits generated by digitizer modules are kept in G4DCofThisEvent class object and the pointer to this container class object is stored in G4Event. See Section 4.5 for the details.
G4EventManager is the manager class to take care of one event. It is responsible for:
converting G4PrimaryVertex and G4PrimaryParticle objects associated with the current G4Event object to G4Track objects. All of G4Track objects representing the primary particles are sent to G4StackManager.
Pop one G4Track object from G4StackManager and send it to G4TrackingManager. The current G4Track object is deleted by G4EventManager after the track is simulated by G4TrackingManager, if the track is marked as "killed".
In case the primary track is "suspended" or "postponed to next event" by G4TrackingManager, it is sent back to the G4StackManager. Secondary G4Track objects returned by G4TrackingManager are also sent to G4StackManager.
When G4StackManager returns
for the "pop" request, G4EventManager terminates the
current processing event.
invokes the user-defined methods
endOfEventAction() from the
G4UserEventAction class. See
Section 6.3 for details.
G4StackManager has three stacks, named urgent, waiting and postpone-to-next-event, which are objects of the G4TrackStack class. By default, all G4Track objects are stored in the urgent stack and handled in a "last in first out" manner. In this case, the other two stacks are not used. However, tracks may be routed to the other two stacks by the user-defined G4UserStackingAction concrete class.
If the methods of G4UserStackingAction have been
overridden by the user, the postpone-to-next-event and
waiting stacks may contain tracks. At the beginning of an
event, G4StackManager checks to see if any tracks left over
from the previous event are stored in the postpone-to-next-event
stack. If so, it attemps to move them to the urgent
stack. But first the
PrepareNewEvent() method of
G4UserStackingAction is called. Here tracks may be
re-classified by the user and sent to the urgent or
waiting stacks, or deferred again to the
postpone-to-next-event stack. As the event is processed
G4StackManager pops tracks from the urgent stack
until it is empty. At this point the
NewStage() method of
G4UserStackingAction is called. In this method tracks from
the waiting stack may be sent to the urgent stack,
retained in the waiting stack or postponed to the next
Details of the user-defined methods of G4UserStackingAction and how they affect track stack management are given in Section 6.3.