G4MicroElecLOPhononModel.cc

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//
// G4MicroElecLOPhononModel.cc, 
//                              2020/05/20 P. Caron, C. Inguimbert are with ONERA [b] 
//                         Q. Gibaru is with CEA [a], ONERA [b] and CNES [c]
//                          M. Raine and D. Lambert are with CEA [a]
//
// A part of this work has been funded by the French space agency(CNES[c])
// [a] CEA, DAM, DIF - 91297 ARPAJON, France
// [b] ONERA - DPHY, 2 avenue E.Belin, 31055 Toulouse, France
// [c] CNES, 18 av.E.Belin, 31401 Toulouse CEDEX, France
//
// Based on the following publications
//
//      - J. Pierron, C. Inguimbert, M. Belhaj, T. Gineste, J. Puech, M. Raine
//        Electron emission yield for low energy electrons: 
//        Monte Carlo simulation and experimental comparison for Al, Ag, and Si
//        Journal of Applied Physics 121 (2017) 215107. 
//               https://doi.org/10.1063/1.4984761
//
//      - P. Caron,
//        Study of Electron-Induced Single-Event Upset in Integrated Memory Devices
//        PHD, 16th October 2019
//
//  - Q.Gibaru, C.Inguimbert, P.Caron, M.Raine, D.Lambert, J.Puech, 
//        Geant4 physics processes for microdosimetry and secondary electron emission simulation : 
//        Extension of MicroElec to very low energies and new materials
//        NIM B, 2020, in review.
//
//
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#include "G4MicroElecLOPhononModel.hh"
#include "G4SystemOfUnits.hh"
#include "G4PhysicalConstants.hh"
 
G4MicroElecLOPhononModel::G4MicroElecLOPhononModel(const G4ParticleDefinition*,
                 const G4String& nam) 
  : G4VEmModel(nam)
{
  fParticleChangeForGamma = GetParticleChangeForGamma();
}
 
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G4MicroElecLOPhononModel::~G4MicroElecLOPhononModel() 
{}
 
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void G4MicroElecLOPhononModel::Initialise(const G4ParticleDefinition*,
                          const G4DataVector& /*cuts*/)
{  
  if (isInitialised) { return; }
  fParticleChangeForGamma = GetParticleChangeForGamma();
  isInitialised = true;
}
 
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G4double G4MicroElecLOPhononModel::CrossSectionPerVolume(const G4Material* material,
                        const G4ParticleDefinition*,
                        G4double ekin,
                        G4double, G4double)
{
  if (material->GetName()!="G4_SILICON_DIOXIDE") return 0.0;
 
  const G4double e = CLHEP::eplus / CLHEP::coulomb;
  const G4double m0 = CLHEP::electron_mass_c2 / (CLHEP::c_squared*CLHEP::kg);
  const G4double h = CLHEP::hbar_Planck * CLHEP::s/ (CLHEP::m2*CLHEP::kg);
  const G4double eps0 = CLHEP::epsilon0 * CLHEP::m/ (CLHEP::farad);
  const G4double kb = CLHEP::k_Boltzmann * CLHEP::kelvin/ CLHEP::joule;
 
  // Parameters SiO2  
  phononEnergy = (0.75*0.153+0.25*0.063 )* CLHEP::eV;
  const G4double eps = 3.84;
  const G4double einf = 2.25;
  const G4double T = 300;  // should be taken from material property
      
  G4double E =(ekin/CLHEP::eV)*e;
  
  G4double hw = (phononEnergy / CLHEP::eV) * e;
  G4double n = 1.0 / (std::exp(hw / (kb*T)) - 1); //Phonon distribution
    
  G4double signe = (absor) ? -1. : 1.;
    
  G4double racine = std::sqrt(1. + ((-signe*hw) / E));
  
  G4double P = (std::pow(e, 2) / (4 * pi*eps0*h*h)) * (n + 0.5 + signe*0.5) * ((1 / einf) - (1 / eps)) 
    * std::sqrt(m0 / (2 * E)) *hw* std::log((1 + racine) / (signe * 1 + ((-signe)*racine)));
  
  G4double MFP = (std::sqrt(2. * E / m0) / P)*m;
  return 2. / MFP;   
}
 
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void G4MicroElecLOPhononModel::SampleSecondaries(
                               std::vector<G4DynamicParticle*>*,
                   const G4MaterialCutsCouple*,
                   const G4DynamicParticle* aDynamicElectron,
                   G4double, G4double)
{
 
  G4double E = aDynamicElectron->GetKineticEnergy();
  G4double Eprim = (absor) ? E + phononEnergy : E - phononEnergy;   
 
  G4double rand = G4UniformRand();
  G4double B = (E + Eprim + 2 * std::sqrt(E*Eprim)) / (E + Eprim - 2 * std::sqrt(E*Eprim));
  G4double cosTheta = ((E + Eprim) / (2 * std::sqrt(E*Eprim)))*(1 - std::pow(B, rand)) + std::pow(B, rand);
  
  if(Interband){
    cosTheta = 1 - 2 * G4UniformRand(); //Isotrope
  }
  G4double phi = twopi * G4UniformRand();
  G4ThreeVector zVers = aDynamicElectron->GetMomentumDirection();
  G4ThreeVector xVers = zVers.orthogonal();
  G4ThreeVector yVers = zVers.cross(xVers);
  
  G4double xDir = std::sqrt(1. - cosTheta*cosTheta);
  G4double yDir = xDir;
  xDir *= std::cos(phi);
  yDir *= std::sin(phi);
  
  G4ThreeVector zPrimeVers((xDir*xVers + yDir*yVers + cosTheta*zVers));
  
  fParticleChangeForGamma->ProposeMomentumDirection(zPrimeVers.unit());
  fParticleChangeForGamma->SetProposedKineticEnergy(Eprim);
}
 
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