G4hBremsstrahlungModel.cc

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//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4hBremsstrahlungModel
//
// Author:        Vladimir Ivanchenko on base of G4MuBremsstrahlungModel
//
// Creation date: 28.02.2008
//
// Modifications:
//
 
//
// Class Description:
//
//
// -------------------------------------------------------------------
//
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#include "G4hBremsstrahlungModel.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4Log.hh"
#include "G4NistManager.hh"
 
using namespace std;
 
G4hBremsstrahlungModel::G4hBremsstrahlungModel(const G4ParticleDefinition* p,
                           const G4String& nam)
  : G4MuBremsstrahlungModel(p, nam)
{}
 
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G4hBremsstrahlungModel::~G4hBremsstrahlungModel()
{}
 
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G4double G4hBremsstrahlungModel::ComputeDMicroscopicCrossSection(
                                           G4double tkin,
                                           G4double Z,
                                           G4double gammaEnergy)
//  differential cross section
{
  G4double dxsection = 0.;
 
  if(gammaEnergy > tkin) return dxsection;
  //  G4cout << "G4hBremsstrahlungModel m= " << mass 
  //     << "  " << particle->GetParticleName() << G4endl;
  G4double E = tkin + mass ;
  G4double v = gammaEnergy/E ;
  G4double delta = 0.5*mass*mass*v/(E-gammaEnergy);
  G4double rab0=delta*sqrte ;
 
  G4int iz = std::max(G4lrint(Z), 1);
 
  G4double z13 = 1.0/nist->GetZ13(iz);
  G4double dn  = mass*nist->GetA27(iz)/(70.*MeV);
 
  G4double b = (1 == iz) ? bh : btf;
 
  // nucleus contribution logarithm
  G4double rab1=b*z13;
  G4double fn=G4Log(rab1/(dn*(electron_mass_c2+rab0*rab1))*
              (mass+delta*(dn*sqrte-2.))) ;
  fn = std::max(fn, 0.0);
 
  G4double x = 1.0 - v;
  if(particle->GetPDGSpin() != 0) { x += 0.75*v*v; }
 
  dxsection = coeff*x*Z*Z*fn/gammaEnergy;
 
  return dxsection;
}
 
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