G4INCLIntersection.cc

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//
// INCL++ intra-nuclear cascade model
// Pekka Kaitaniemi, CEA and Helsinki Institute of Physics
// Davide Mancusi, CEA
// Alain Boudard, CEA
// Sylvie Leray, CEA
// Joseph Cugnon, University of Liege
//
#define INCLXX_IN_GEANT4_MODE 1

#include "globals.hh"

#include "G4INCLIntersection.hh"

namespace G4INCL {

  Intersection IntersectionFactory::getTrajectoryIntersection(const ThreeVector &x0, const ThreeVector &v, const G4double r, const G4bool earliest) {
    const G4double scalarVelocity = v.mag();
    ThreeVector velocityUnitVector = v / scalarVelocity;

    ThreeVector positionTransverse = x0 - velocityUnitVector * x0.dot(velocityUnitVector);
    const G4double impactParameter = positionTransverse.mag();

    const G4double r2 = r*r;
    G4double distanceZ2 = r2 - impactParameter * impactParameter;
    if(distanceZ2 < 0.0)
      return Intersection(false, 0.0, ThreeVector());

    const G4double distanceZ = std::sqrt(distanceZ2);
    const ThreeVector position = positionTransverse + velocityUnitVector * (earliest ? -distanceZ : distanceZ);
    const G4double time = (position-x0).dot(velocityUnitVector)/scalarVelocity;
    return Intersection(true, time, position);
  }

}

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