G4hCoulombScatteringModel.cc

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// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4hCoulombScatteringModel
//
// Author:        Vladimir Ivanchenko 
//
// Creation date: 08.06.2012 from G4eCoulombScatteringModel
//
// Modifications:
//
//
// Class Description:
//
// -------------------------------------------------------------------
//
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#include "G4hCoulombScatteringModel.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "Randomize.hh"
#include "G4DataVector.hh"
#include "G4ElementTable.hh"
#include "G4ParticleChangeForGamma.hh"
#include "G4Proton.hh"
#include "G4ParticleTable.hh"
#include "G4IonTable.hh"
#include "G4ProductionCutsTable.hh"
#include "G4NucleiProperties.hh"
#include "G4Pow.hh"
#include "G4NistManager.hh"
 
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G4hCoulombScatteringModel::G4hCoulombScatteringModel(G4bool combined)
  : G4VEmModel("hCoulombScattering"),
    cosThetaMin(1.0),
    cosThetaMax(-1.0),
    isCombined(combined)
{
  fParticleChange = nullptr;
  fNistManager = G4NistManager::Instance();
  theIonTable  = G4ParticleTable::GetParticleTable()->GetIonTable();
  theProton    = G4Proton::Proton();
  currentMaterial = nullptr; 
  fixedCut = -1.0;
 
  pCuts = nullptr;
 
  recoilThreshold = 0.0; // by default does not work
 
  particle = nullptr;
  currentCouple = nullptr;
  wokvi = new G4WentzelVIRelXSection();
 
  currentMaterialIndex = 0;
  mass = CLHEP::proton_mass_c2;
  elecRatio = 0.0;
}
 
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G4hCoulombScatteringModel::~G4hCoulombScatteringModel()
{
  delete wokvi;
}
 
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void G4hCoulombScatteringModel::Initialise(const G4ParticleDefinition* part,
                       const G4DataVector& cuts)
{
  SetupParticle(part);
  currentCouple = nullptr;
 
  // defined theta limit between single and multiple scattering 
  isCombined = true;
  G4double tet = PolarAngleLimit();
 
  if(tet <= 0.0) { 
    cosThetaMin = 1.0; 
    isCombined = false; 
  } else if(tet >= CLHEP::pi) { 
    cosThetaMin = -1.0; 
  } else { 
    cosThetaMin = std::cos(tet); 
  }
 
  wokvi->Initialise(part, cosThetaMin);
  /*
  G4cout << "G4hCoulombScatteringModel: " << particle->GetParticleName()
         << "  1-cos(ThetaLimit)= " << 1 - cosThetaMin
     << "  cos(thetaMax)= " <<  cosThetaMax
     << G4endl;
  */
  pCuts = &cuts;
  //G4ProductionCutsTable::GetProductionCutsTable()->GetEnergyCutsVector(3);
  /*
  G4cout << "!!! G4hCoulombScatteringModel::Initialise for " 
     << part->GetParticleName() << "  cos(TetMin)= " << cosThetaMin 
     << "  cos(TetMax)= " << cosThetaMax <<G4endl;
  G4cout << "cut= " << (*pCuts)[0] << "  cut1= " << (*pCuts)[1] << G4endl;
  */
  if(!fParticleChange) {
    fParticleChange = GetParticleChangeForGamma();
  }
  if(IsMaster() && mass < CLHEP::GeV && part->GetParticleName() != "GenericIon") {
    InitialiseElementSelectors(part, cuts);
  } 
}
 
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void G4hCoulombScatteringModel::InitialiseLocal(const G4ParticleDefinition*, 
                        G4VEmModel* masterModel)
{
  SetElementSelectors(masterModel->GetElementSelectors());
}
 
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G4double 
G4hCoulombScatteringModel::MinPrimaryEnergy(const G4Material* material,
                        const G4ParticleDefinition* part,
                        G4double)
{
  SetupParticle(part);
 
  // define cut using cuts for proton
  G4double cut = 
    std::max(recoilThreshold, (*pCuts)[CurrentCouple()->GetIndex()]);
 
  // find out lightest element
  const G4ElementVector* theElementVector = material->GetElementVector();
  std::size_t nelm = material->GetNumberOfElements();
 
  // select lightest element
  G4int Z = 300;
  for (std::size_t j=0; j<nelm; ++j) {
    Z = std::min(Z,(*theElementVector)[j]->GetZasInt());
  }
  G4int A = G4lrint(fNistManager->GetAtomicMassAmu(Z));
  G4double targetMass = G4NucleiProperties::GetNuclearMass(A, Z);
  G4double t = std::max(cut, 0.5*(cut + std::sqrt(2*cut*targetMass)));
 
  return t;
}
 
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G4double G4hCoulombScatteringModel::ComputeCrossSectionPerAtom(
                const G4ParticleDefinition* p,
        G4double kinEnergy,
        G4double Z, G4double,
        G4double cutEnergy, G4double)
{
  //G4cout << "### G4hCoulombScatteringModel::ComputeCrossSectionPerAtom  for " 
  //<< p->GetParticleName()<<" Z= "<<Z<<" e(MeV)= "<< kinEnergy/MeV << G4endl; 
  G4double cross = 0.0;
  elecRatio = 0.0;
  if(p != particle) { SetupParticle(p); }
 
  // cross section is set to zero to avoid problems in sample secondary
  if(kinEnergy <= 0.0) { return cross; }
  DefineMaterial(CurrentCouple());
 
  G4int iz = G4lrint(Z);
  G4double tmass = (1 == iz) ? proton_mass_c2 :
    fNistManager->GetAtomicMassAmu(iz)*amu_c2; 
  wokvi->SetTargetMass(tmass);
 
  G4double costmin = 
    wokvi->SetupKinematic(kinEnergy, currentMaterial);
 
  if(cosThetaMax < costmin) {
    G4double cut = (0.0 < fixedCut) ? fixedCut : cutEnergy;
    costmin = wokvi->SetupTarget(iz, cut);
    G4double costmax = 
      (1 == iz && particle == theProton && cosThetaMax < 0.0) 
      ? 0.0 : cosThetaMax; 
    if(costmin > costmax) {
      cross = wokvi->ComputeNuclearCrossSection(costmin, costmax)
    + wokvi->ComputeElectronCrossSection(costmin, costmax);
    }
    /*  
  if(p->GetParticleName() == "mu+") 
  G4cout << "e(MeV)= " << kinEnergy/MeV << " cross(b)= " << cross/barn  
     << " 1-costmin= " << 1-costmin
     << " 1-costmax= " << 1-costmax
     << " 1-cosThetaMax= " << 1-cosThetaMax
     << G4endl;
    */
  }
  return cross;  
}
 
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void G4hCoulombScatteringModel::SampleSecondaries(
                std::vector<G4DynamicParticle*>* fvect,
        const G4MaterialCutsCouple* couple,
        const G4DynamicParticle* dp,
        G4double cutEnergy,
        G4double)
{
  G4double kinEnergy = dp->GetKineticEnergy();
  SetupParticle(dp->GetDefinition());
  DefineMaterial(couple);
 
  // Choose nucleus
  G4double cut = (0.0 < fixedCut) ? fixedCut : cutEnergy;
 
  const G4Element* elm = SelectRandomAtom(couple,particle,
                      kinEnergy,cut,kinEnergy);
 
  G4int iz = elm->GetZasInt();
  G4int ia = SelectIsotopeNumber(elm);
  G4double mass2 = G4NucleiProperties::GetNuclearMass(ia, iz);
 
  wokvi->SetTargetMass(mass2);
  wokvi->SetupKinematic(kinEnergy, currentMaterial);
  G4double costmin = wokvi->SetupTarget(iz, cut);
  G4double costmax = (1 == iz && particle == theProton && cosThetaMax < 0.0) 
    ? 0.0 :  cosThetaMax; 
  if(costmin <= costmax) { return; }
 
  G4double cross = wokvi->ComputeNuclearCrossSection(costmin, costmax);
  G4double ecross = wokvi->ComputeElectronCrossSection(costmin, costmax);
  G4double ratio = ecross/(cross + ecross);
 
  G4ThreeVector newDirection = 
    wokvi->SampleSingleScattering(costmin, costmax, ratio);
 
  // kinematics in the Lab system
  G4double ptot = std::sqrt(kinEnergy*(kinEnergy + 2.0*mass));
  G4double e1   = mass + kinEnergy;
  
  // Lab. system kinematics along projectile direction
  G4LorentzVector v0 = G4LorentzVector(0, 0, ptot, e1+mass2);
  G4LorentzVector v1 = G4LorentzVector(0, 0, ptot, e1);
  G4ThreeVector bst = v0.boostVector();
  v1.boost(-bst);
  // CM projectile
  G4double momCM = v1.pz(); 
  
  // Momentum after scattering of incident particle
  v1.setX(momCM*newDirection.x());
  v1.setY(momCM*newDirection.y());
  v1.setZ(momCM*newDirection.z());
 
  // CM--->Lab
  v1.boost(bst);
 
  G4ThreeVector dir = dp->GetMomentumDirection(); 
  newDirection = v1.vect().unit();
  newDirection.rotateUz(dir);   
  
  fParticleChange->ProposeMomentumDirection(newDirection);   
  
  // recoil
  v0 -= v1; 
  G4double trec = std::max(v0.e() - mass2, 0.0);
  G4double edep = 0.0;
 
  G4double tcut = recoilThreshold;
  if(pCuts) { tcut= std::max(tcut,(*pCuts)[currentMaterialIndex]); }
 
  if(trec > tcut) {
    G4ParticleDefinition* ion = theIonTable->GetIon(iz, ia, 0);
    newDirection = v0.vect().unit();
    newDirection.rotateUz(dir);   
    auto newdp = new G4DynamicParticle(ion, newDirection, trec);
    fvect->push_back(newdp);
  } else if(trec > 0.0) {
    edep = trec;
    fParticleChange->ProposeNonIonizingEnergyDeposit(edep);
  }
 
  // finelize primary energy and energy balance
  G4double finalT = v1.e() - mass;
  if(finalT < 0.0) { 
    edep += finalT;
    finalT = 0.0;
  } 
  edep = std::max(edep, 0.0);
  fParticleChange->SetProposedKineticEnergy(finalT);
  fParticleChange->ProposeLocalEnergyDeposit(edep);
}
 
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