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Question Re: G4Transportation is killing track (Q#45!!!) 

Keywords: electrons, magnetic field, transportation
Forum: Fields: Magnetic and Otherwise
Re: Question G4Transportation is killing track (Q#45!!!) (Ilya)
Re: Feedback Re: G4Transportation is killing track (Q#45!!!) (John Apostolakis)
Date: 27 May, 2008
From: Robert Bernstein <rhbob@fnal.gov>

Hi,

I am looping a 100 MeV track in a 10 kG magnetic field for a muon-electron conversion 
experiment -- so I want that energy/field pair --and am getting this message.

 I added the following code (currently the field is uniform but it will vary slightly later)
which of course is just your example N03 and I *still* get the message, but much later.  I think
my value for new_max is absurd, so I must be doing something wrong.  It did change
the result, though, so I must be doing something correctly.

 --thanks, Robert Bernstein

#include "G4FieldManager.hh"
#include "G4TransportationManager.hh"
#include "G4PropagatorInField.hh"
#include "G4Navigator.hh"

void mu2eDetectorConstruction::SetMagField(G4double fieldValue)
{
  //apply a global uniform magnetic field along Z axis
  G4FieldManager* fieldMgr
   = G4TransportationManager::GetTransportationManager()->GetFieldManager();

  //
  // have to do this because GEANT kills the particle with a "G4Transportation is killing track" error
  // it it seems to loop too much
  //
  G4Navigator* navigate = new G4Navigator();
  G4PropagatorInField* fieldProp = new G4PropagatorInField(navigate,fieldMgr);
  G4int new_max = 1000000;
  fieldProp->SetMaxLoopCount(new_max);

  if(magField) delete magField;		//delete the existing magn field

  if(fieldValue!=0.)			// create a new one if non nul
  { magField = new G4UniformMagField(G4ThreeVector(0.,0.,fieldValue));
    fieldMgr->SetDetectorField(magField);
    fieldMgr->CreateChordFinder(magField);
  } else {
    magField = 0;
    fieldMgr->SetDetectorField(magField);
  }
}

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1 None: Re: G4Transportation is killing track (Q#45!!!)   (Tatiana Nikitina - 27 May, 2008)
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