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// $Id: G4hBremsstrahlungModel.cc,v 1.3 2008/07/22 16:15:16 vnivanch Exp $
// GEANT4 tag $Name: geant4-09-02 $
//
// -------------------------------------------------------------------
//
// 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"

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 = G4int(Z);
  if(iz < 1) iz = 1;

  G4double z13 = 1.0/nist->GetZ13(iz);
  G4double dn  = mass*nist->GetA27(iz)/(70.*MeV);

  G4double    b = btf;
  if(1 == iz) b = bh;

  // nucleus contribution logarithm
  G4double rab1=b*z13;
  G4double fn=log(rab1/(dn*(electron_mass_c2+rab0*rab1))*
              (mass+delta*(dn*sqrte-2.))) ;
  if(fn <0.) fn = 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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