G4INCLReflectionChannel.cc

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00025 //
00026 // INCL++ intra-nuclear cascade model
00027 // Pekka Kaitaniemi, CEA and Helsinki Institute of Physics
00028 // Davide Mancusi, CEA
00029 // Alain Boudard, CEA
00030 // Sylvie Leray, CEA
00031 // Joseph Cugnon, University of Liege
00032 //
00033 #define INCLXX_IN_GEANT4_MODE 1
00034 
00035 #include "globals.hh"
00036 
00037 #include "G4INCLReflectionChannel.hh"
00038 #include "G4INCLFinalState.hh"
00039 #include "G4INCLRandom.hh"
00040 #include "G4INCLINuclearPotential.hh"
00041 
00042 #include <cmath>
00043 
00044 namespace G4INCL {
00045   const G4double ReflectionChannel::sinMinReflectionAngleSquaredOverFour = std::pow(std::sin(2.*Math::pi/200.),2.);
00046   const G4double ReflectionChannel::positionScalingFactor = 0.99;
00047 
00048   ReflectionChannel::ReflectionChannel(Nucleus *n, Particle *p)
00049     :theNucleus(n),theParticle(p)
00050   {
00051   }
00052 
00053   ReflectionChannel::~ReflectionChannel()
00054   {
00055   }
00056 
00057   FinalState* ReflectionChannel::getFinalState()
00058   {
00059     FinalState *fs = new FinalState(); // Create final state for the output
00060     fs->setTotalEnergyBeforeInteraction(theParticle->getEnergy() - theParticle->getPotentialEnergy());
00061 
00062     const ThreeVector &oldMomentum = theParticle->getMomentum();
00063     G4double pspr = theParticle->getPosition().dot(oldMomentum);
00064     if(pspr>=0) { // This means that the particle is trying to leave; perform a reflection
00065       const G4double x2cour = theParticle->getPosition().mag2();
00066       const ThreeVector newMomentum = oldMomentum - (theParticle->getPosition() * (2.0 * pspr/x2cour));
00067       const G4double deltaP2 = (newMomentum-oldMomentum).mag2();
00068       theParticle->setMomentum(newMomentum);
00069       const G4double minDeltaP2 = sinMinReflectionAngleSquaredOverFour * newMomentum.mag2();
00070       if(deltaP2 < minDeltaP2) { // Avoid extremely small reflection angles
00071         theParticle->setPosition(theParticle->getPosition() * positionScalingFactor);
00072         DEBUG("Reflection angle for particle " << theParticle->getID() << " was too tangential: " << std::endl
00073             << "  " << deltaP2 << "=deltaP2<minDeltaP2=" << minDeltaP2 << std::endl
00074             << "  Resetting the particle position to ("
00075             << theParticle->getPosition().getX() << ", "
00076             << theParticle->getPosition().getY() << ", "
00077             << theParticle->getPosition().getZ() << ")" << std::endl);
00078       }
00079       theNucleus->updatePotentialEnergy(theParticle);
00080     } else { // The particle momentum is already directed towards the inside of the nucleus; do nothing
00081       // ...but make sure this only happened because of the frozen propagation
00082 // assert(theParticle->getPosition().dot(theParticle->getPropagationVelocity())>0.);
00083     }
00084 
00085     theParticle->thawPropagation();
00086     fs->addModifiedParticle(theParticle);
00087     return fs;
00088   }
00089 }
00090 

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