|Message: Re: Insert a local electric field inside GEANT4||Not Logged In (login)|
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Good questions. I will try to shine some light on our logical and legitimate questions and impressions, which unfortunately are due to rather old comments!
>>> G4MagIntegratorStepper* myStepper = new G4ClassicalRK4(myEquation,nvar); > Does that really work? Because G4ClassicalRK4 is inherit from > class G4MagErrorStepper; and according to the comment > of the source file in G4MagErrorStepper.hh:
Most steppers can be used for all fields: steppers are general except those deriving from G4MagHelicalStepper which assumes that the field is magnetic and uses the helix as zero-eth order solution:
G4MagIntegratorStepper <---- abstract/general ( "G4VIntegratorStepper") G4CashKarpRKF45 <---- general G4MagErrorStepper <---- general (mid-point methods) ... many G4MagHelicalStepper <---- only for magnetic
I note too that unfortunately currently G4RKG3_Stepper is not working, as it reports if you try to use.
> which [class] is used to calculate the electric field?
The class that calculates the electric field in this case is G4UniformElectricField, called by G4EqMagElectricField, which you have registered to your stepper.
I note also that since Geant4 6.0 there is a small refinement that can simplify the code very slightly -- although the old recommended code below still works.
>> G4bool fieldChangesEnergy = true; >> >> G4FieldManager* pFieldMgr = >> new G4FieldManager(myField,pChordFinder,FieldChangeEnergy);
If you say instead G4FieldManager* pFieldMgr = new G4FieldManager(myField,pChordFinder); the field manager will get the information about whether the field changes a track's energy from the field itself (where it is available since a small reorganisation of classes in release 6.0).
I hope this helps to clear up the situation.
Best regards, John Apostolakis.
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