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Forum: Fields: Magnetic and Otherwise
Re: Question Electrons misteriously killed (Lafont Fabien)
Re: Feedback Re: Electrons misteriously killed (Gumplinger Peter)
Date: 15 Apr, 2014
From: Lafont Fabien <Lafont Fabien>

Dear Peter and John,

Thanks for your answers

I may have misspoke myself :

My geometry is the following one :

World volume consists in a box large enough to contain his daughter volume, the tub (rmin=46 mm, rmax=50 mm, length=1.2 m) which constitutes the "wall". There are also two ends plates acting as detectors at both ends of the tub.


> > My problem comes from some electrons that are killed somewhere in the
> > vaccum of the tub (this is actually the world volume)

What I was trying to say was that my electrons travel only between r = 0 and r =46 mm and the two end plates located at z = -600 mm & z = 600 mm.
So there are travelling in the "World volume" composed of vacuum. 


I tried what John mentionned but it seems it does not change anything...
I tried to change the parameters during the initialization of the physics list but there are still some electrons that are killed.

Maybe I do not call the methods in the right way/ or right "place"...
Should I call these method in my physics list initialization ?

Otherwise, I tried to change the values of delta chord,delta intersection , min epsilon step, max epsilon step and so on, and there is no killed electrons anymore when I set very high values such 1*m and epsilon between 0.1 & 1... Obviously trajectories looks very bad...

Here is the field initialization for my global magnetic field in my detectorCOnstruction class :

##################################################################

      G4FieldManager* pFieldMgr;
      G4MagIntegratorStepper* pStepper;
      G4Mag_UsualEqRhs* pEquation;
    
      G4MagneticField* Field= new TabulatedField3D();
      
      pEquation = new G4Mag_UsualEqRhs (Field);
      pStepper = new G4ClassicalRK4 (pEquation);
    pFieldMgr=G4TransportationManager::GetTransportationManager()->GetFieldManager();
      
      G4ChordFinder *pChordFinder = new G4ChordFinder(Field,1e-9*m,pStepper);
      pFieldMgr->SetChordFinder( pChordFinder );
      
      pFieldMgr->SetDetectorField(Field);

      pFieldMgr->GetChordFinder()->SetDeltaChord(1.e-9*m);
      pFieldMgr->SetDeltaIntersection(1.e-9*m);
      pFieldMgr->SetDeltaOneStep(1.e-9*m);

      G4PropagatorInField *propInField;
      propInField =
     G4TransportationManager::GetTransportationManager()->GetPropagatorInField();
      propInField->SetMinimumEpsilonStep(1e-11);
      propInField->SetMaximumEpsilonStep(1e-10);

############################################################

It mays also be related to the stepper type.
I am going to like further after this but if you have more ideas, please do not hesitate.

Thanks again for your help.

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