The user can define artificial limits affecting to the Geant4 tracking.
G4UserLimits(G4double uStepMax = DBL_MAX, G4double uTrakMax = DBL_MAX, G4double uTimeMax = DBL_MAX, G4double uEkinMin = 0., G4double uRangMin = 0. );
uStepMax
| Maximum step length |
uTrakMax
| Maximum total track length |
uTimeMax
| Maximum global time for a track |
uEkinMin
| Minimum remaining kinetic energy for a track |
uRangMin
| Minimum remaining range for a track |
Note that uStepMax
is affecting to each step, while all
other limits are affecting to a track.
The user can assign G4UserLimits
to logical volume and/or
to a region. User limits assigned to logical volume do not
propagate to daughter volumes, while User limits assigned to region
propagate to daughter volumes unless daughters belong to another
region. If both logical volume and associated region have user
limits, those of logical volume win.
A G4UserLimits object must be instantiated for the duration of whatever logical volume or region to which it is assigned. It is the responsibility of the user's code to delete the object after the assigned volume(s)/region(s) have been deleted.
In addition to instantiating G4UserLimits
and setting it
to logical volume or region, the user has to assign the following
process(es) to particle types he/she wants to affect. If none of
these processes is assigned, that kind of particle is not affected
by G4UserLimits
.
uStepMax
)
G4StepLimiter
process must be defined to affected
particle types. This process limits a step, but it does not kill a
track.
uTrakMax, uTimeMax, uEkinMin,
uRangMin
)
G4UserSpecialCuts
process must be defined to affected
particle types. This process limits a step and kills the track when
the track comes to one of these limits. Step limitation occurs only
for the final step.
Example of G4UserLimits
can be found in
examples/basic/B2 : see B2aDetectorConstruction
(or
B2bDetectorConstruction
). The G4StepLimiter
process is added in the Geant4 physics list via the G4StepLimiterBuilder
class in the main()
function in exampleB4a.cc
(or exampleB4b.cc
).