G4INCL::anonymous_namespace{G4INCLPhaseSpaceGenerator.cc} Namespace Reference

Functions
void	bias (ParticleList &particles, const ThreeVector &pInVec, const G4double slope)
	Actually perform the biasing. More...

Variables
G4ThreadLocal Particle *	biasMe
G4ThreadLocal IPhaseSpaceGenerator *	thePhaseSpaceGenerator

Function Documentation

bias()

void G4INCL::anonymous_namespace{G4INCLPhaseSpaceGenerator.cc}::bias	(	ParticleList &	particles,
		const ThreeVector &	pInVec,
		const G4double	slope
	)

Actually perform the biasing.

Parameters

particles	list of particles to bias
pInVec	momentum of the particle to be biased before the collision
slope	the parameter in

Definition at line 55 of file G4INCLPhaseSpaceGenerator.cc.

                                                                                        {
      const G4double pIn = pInVec.mag();
      const ThreeVector collisionAxis = pInVec/pIn;
      const ThreeVector pMomVec = biasMe->getMomentum();
      const G4double pMom = pMomVec.mag();
      if(pMom ==0.) return;
      const G4double pMomCosAng = pMomVec.dot(collisionAxis)/pMom;
      const G4double pMomAng = Math::arcCos(pMomCosAng); // Angle between the original axis of the dominant particle and is new one after generate
 
      // compute the target angle for the biasing
      // it is drawn from a exp(Bt) distribution
      const G4double cosAngSlope = 2e-6 * slope * pIn * pMom;
      const G4double cosAng = 1. + std::log(1. - Random::shoot()*(1.-std::exp(-2.*cosAngSlope)))/cosAngSlope;
      const G4double ang = Math::arcCos(cosAng);
 
      // compute the rotation angle
      const G4double rotationAngle = ang - pMomAng;
 
      // generate the rotation axis; it is perpendicular to collisionAxis and
      // pMomVec
      ThreeVector rotationAxis;
      if(pMomAng>1E-10) {
        rotationAxis = collisionAxis.vector(pMomVec);
        const G4double axisLength = rotationAxis.mag();
        const G4double oneOverLength = 1./axisLength;
        rotationAxis *= oneOverLength;
      } else {
        // need to jump through some hoops if collisionAxis is nearly aligned
        // with pMomVec
        rotationAxis = collisionAxis.anyOrthogonal();
      }
 
      // apply the rotation
      particles.rotateMomentum(rotationAngle, rotationAxis);
    }

References G4INCL::ThreeVector::anyOrthogonal(), G4INCL::Math::arcCos(), biasMe, G4INCL::ThreeVector::dot(), G4INCL::Particle::getMomentum(), G4INCL::ThreeVector::mag(), G4INCL::ParticleList::rotateMomentum(), G4INCL::Random::shoot(), and G4INCL::ThreeVector::vector().

Referenced by G4INCL::PhaseSpaceGenerator::generateBiased().

Variable Documentation

biasMe

G4ThreadLocal Particle* G4INCL::anonymous_namespace{G4INCLPhaseSpaceGenerator.cc}::biasMe

Definition at line 47 of file G4INCLPhaseSpaceGenerator.cc.

Referenced by bias(), and G4INCL::PhaseSpaceGenerator::generateBiased().

thePhaseSpaceGenerator

G4ThreadLocal IPhaseSpaceGenerator* G4INCL::anonymous_namespace{G4INCLPhaseSpaceGenerator.cc}::thePhaseSpaceGenerator

Definition at line 45 of file G4INCLPhaseSpaceGenerator.cc.

Referenced by G4INCL::PhaseSpaceGenerator::deletePhaseSpaceGenerator(), G4INCL::PhaseSpaceGenerator::generate(), G4INCL::PhaseSpaceGenerator::getPhaseSpaceGenerator(), and G4INCL::PhaseSpaceGenerator::setPhaseSpaceGenerator().