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// $Id: G4VMscModel.cc,v 1.13 2009/07/20 17:32:47 vnivanch Exp $
// GEANT4 tag $Name: geant4-09-03 $
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4VMscModel
//
// Author:        Vladimir Ivanchenko
//
// Creation date: 07.03.2008
//
// Modifications:
//
//
// Class Description:
//
// General interface to msc models

// -------------------------------------------------------------------
//

#include "G4VMscModel.hh"
#include "G4ParticleChangeForMSC.hh"
#include "G4TransportationManager.hh"

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G4VMscModel::G4VMscModel(const G4String& nam):
  G4VEmModel(nam), 
  safetyHelper(0),
  facrange(0.04),
  facgeom(2.5),
  facsafety(0.3),
  skin(3.0),
  dtrl(0.05),
  lambdalimit(mm),
  geommax(1.e50*mm),
  steppingAlgorithm(fUseSafety),
  samplez(false),
  latDisplasment(true)
{}

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G4VMscModel::~G4VMscModel()
{}

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G4ParticleChangeForMSC* G4VMscModel::GetParticleChangeForMSC()
{
  G4ParticleChangeForMSC* p = 0;
  if (pParticleChange) {
    p = static_cast<G4ParticleChangeForMSC*>(pParticleChange);
  } else {
    p = new G4ParticleChangeForMSC();
  }
  return p;
}

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void G4VMscModel::InitialiseSafetyHelper()
{
  if(!safetyHelper) {
    safetyHelper = G4TransportationManager::GetTransportationManager()
      ->GetSafetyHelper();
    safetyHelper->InitialiseHelper();
  }
}

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void G4VMscModel::ComputeDisplacement(G4ParticleChangeForMSC* fParticleChange,  
				      const G4ThreeVector& dir,
				      G4double displacement,
				      G4double postsafety)
{
  const G4ThreeVector* pos = fParticleChange->GetProposedPosition();
  G4double r = displacement;
  if(r >  postsafety) {
    G4double newsafety = safetyHelper->ComputeSafety(*pos);
    if(r > newsafety) r = newsafety;
  }
  if(r > 0.) {

    // compute new endpoint of the Step
    G4ThreeVector newPosition = *pos + r*dir;

    // definitely not on boundary
    if(displacement == r) {
      safetyHelper->ReLocateWithinVolume(newPosition);

    } else {
      // check safety after displacement
      G4double postsafety = safetyHelper->ComputeSafety(newPosition);

      // displacement to boundary
      if(postsafety <= 0.0) {
	safetyHelper->Locate(newPosition, 
			     *fParticleChange->GetProposedMomentumDirection());

	// not on the boundary
      } else {
	safetyHelper->ReLocateWithinVolume(newPosition);
      }
    }
    fParticleChange->ProposePosition(newPosition);
  }
}

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void G4VMscModel::SampleScattering(const G4DynamicParticle*, G4double)
{}

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G4double G4VMscModel::ComputeTruePathLengthLimit(const G4Track&, 
						 G4PhysicsTable*, 
						 G4double)
{
  return DBL_MAX;
}

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G4double G4VMscModel::ComputeGeomPathLength(G4double truePathLength)
{
  return truePathLength;
}

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G4double G4VMscModel::ComputeTrueStepLength(G4double geomPathLength)
{
  return geomPathLength;
}

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void G4VMscModel::SampleSecondaries(std::vector<G4DynamicParticle*>*,
				    const G4MaterialCutsCouple*,
				    const G4DynamicParticle*,
				    G4double, G4double)
{}

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