G4DNARuddAngle.cc

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//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4DNARuddAngle
//
// Author:        Vladimir Ivantcheko
// 
// Creation date: 23 August 2013
//
// Modifications: 
//
// Class Description: 
//
// Delta-electron Angular Distribution Generation 
//
// Class Description: End 
//
// -------------------------------------------------------------------
//

#include "G4DNARuddAngle.hh"
#include "G4PhysicalConstants.hh"
#include "Randomize.hh"
#include "G4ParticleDefinition.hh"
#include "G4Electron.hh"
#include "G4SystemOfUnits.hh"

using namespace std;

G4DNARuddAngle::G4DNARuddAngle(const G4String&)
  : G4VEmAngularDistribution("deltaRudd")
{
  fElectron = G4Electron::Electron();
}    

G4DNARuddAngle::~G4DNARuddAngle() 
{}

G4ThreeVector& 
G4DNARuddAngle::SampleDirectionForShell(const G4DynamicParticle* dp,
          G4double secKinetic, G4int, 
          G4int, 
          const G4Material*)
{
  G4double k = dp->GetKineticEnergy();
  G4double cosTheta = 1.0;

  const G4ParticleDefinition* particle = dp->GetDefinition();
  G4double mass = particle->GetPDGMass();

  G4double maximumEnergyTransfer = k;
  if(particle == fElectron) { maximumEnergyTransfer *= 0.5; }
  else if(mass > MeV) {
    G4double ratio = electron_mass_c2/mass;
    G4double tau  = k/mass;
    maximumEnergyTransfer = 2.0*electron_mass_c2*tau*(tau + 2.) /
      (1. + 2.0*(tau + 1.)*ratio + ratio*ratio);
    
  }

  if (secKinetic>100*eV && secKinetic <= maximumEnergyTransfer) {
    cosTheta = std::sqrt(secKinetic / maximumEnergyTransfer);
  } else {
    cosTheta = (2.*G4UniformRand())-1.;
  }

  G4double sint = sqrt((1.0 - cosTheta)*(1.0 + cosTheta));
  G4double phi  = twopi*G4UniformRand(); 

  fLocalDirection.set(sint*cos(phi), sint*sin(phi), cosTheta);
  fLocalDirection.rotateUz(dp->GetMomentumDirection());

  return fLocalDirection;
}

G4ThreeVector& 
G4DNARuddAngle::SampleDirection(const G4DynamicParticle* dp,
        G4double secEkin, G4int Z, 
        const G4Material* mat)
{
  return SampleDirectionForShell(dp, secEkin, Z, 0, mat);
}

void G4DNARuddAngle::PrintGeneratorInformation() const
{}