G4PAIModel.cc

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// $Id: G4PAIModel.cc 73607 2013-09-02 10:04:03Z gcosmo $
//
// -------------------------------------------------------------------
//
// GEANT4 Class
// File name:     G4PAIModel.cc
//
// Author: Vladimir.Grichine@cern.ch on base of V.Ivanchenko model interface
//
// Creation date: 05.10.2003
//
// Modifications:
//
// 17.08.04 V.Grichine, bug fixed for Tkin<=0 in SampleSecondary
// 16.08.04 V.Grichine, bug fixed in massRatio for DEDX, CrossSection, 
//          SampleSecondary
// 08.04.05 Major optimisation of internal interfaces (V.Ivantchenko)
// 26.07.09 Fixed logic to work with several materials (V.Ivantchenko)
// 21.11.10 V. Grichine verbose flag for protons and G4PAYySection to 
//          check sandia table 
// 12.06.13 V. Grichine Bug fixed in SampleSecondaries for scaled Tkin 
//          (fMass -> proton_mass_c2)
// 19.08.13 V.Ivanchenko extract data handling to G4PAIModelData class 
//          added sharing of internal data between threads (MT migration)
//

#include "G4PAIModel.hh"

#include "G4SystemOfUnits.hh"
#include "G4PhysicalConstants.hh"
#include "G4Region.hh"
#include "G4PhysicsLogVector.hh"
#include "G4PhysicsFreeVector.hh"
#include "G4PhysicsTable.hh"
#include "G4ProductionCutsTable.hh"
#include "G4MaterialCutsCouple.hh"
#include "G4MaterialTable.hh"
#include "G4SandiaTable.hh"
#include "G4OrderedTable.hh"

#include "Randomize.hh"
#include "G4Electron.hh"
#include "G4Positron.hh"
#include "G4Poisson.hh"
#include "G4Step.hh"
#include "G4Material.hh"
#include "G4DynamicParticle.hh"
#include "G4ParticleDefinition.hh"
#include "G4ParticleChangeForLoss.hh"
#include "G4PAIModelData.hh"
#include "G4DeltaAngle.hh"


using namespace std;

G4PAIModel::G4PAIModel(const G4ParticleDefinition* p, const G4String& nam)
  : G4VEmModel(nam),G4VEmFluctuationModel(nam),
    fVerbose(0),
    fModelData(0),
    fParticle(0)
{  
  fElectron = G4Electron::Electron();
  fPositron = G4Positron::Positron();

  fParticleChange = 0;

  if(p) { SetParticle(p); }
  else  { SetParticle(fElectron); }

  // default generator
  SetAngularDistribution(new G4DeltaAngle());

  isInitialised = false;
}


G4PAIModel::~G4PAIModel()
{
  if(IsMaster()) { delete fModelData; }
}


void G4PAIModel::Initialise(const G4ParticleDefinition* p,
                            const G4DataVector& cuts)
{
  if(fVerbose > 0) {
    G4cout<<"G4PAIModel::Initialise for "<<p->GetParticleName()<<G4endl;
  }

  if(isInitialised) { return; }
  isInitialised = true;

  SetParticle(p);
  fParticleChange = GetParticleChangeForLoss();

  if(IsMaster()) { 

    InitialiseElementSelectors(p, cuts);

    if(!fModelData) {

      G4double tmin = LowEnergyLimit()*fRatio;
      G4double tmax = HighEnergyLimit()*fRatio;
      fModelData = new G4PAIModelData(tmin, tmax, fVerbose);
    }
    // Prepare initialization
    const G4MaterialTable* theMaterialTable = G4Material::GetMaterialTable();
    size_t numOfMat   = G4Material::GetNumberOfMaterials();
    size_t numRegions = fPAIRegionVector.size();

    for(size_t iReg = 0; iReg < numRegions; ++iReg) {
      const G4Region* curReg = fPAIRegionVector[iReg];
      G4Region* reg = const_cast<G4Region*>(curReg);

      for(size_t jMat = 0; jMat < numOfMat; ++jMat) {
        G4Material* mat = (*theMaterialTable)[jMat];
        const G4MaterialCutsCouple* cutCouple = reg->FindCouple(mat);
        //G4cout << "Couple <" << fCutCouple << G4endl;
        if(cutCouple) {
          /*
            G4cout << "Reg <" <<curReg->GetName() << ">  mat <" 
            << fMaterial->GetName() << ">  fCouple= " 
            << fCutCouple << " idx= " << fCutCouple->GetIndex()
            <<"  " << p->GetParticleName() <<G4endl;
            // G4cout << cuts.size() << G4endl;
            */
          // check if this couple is not already initialized
          size_t n = fMaterialCutsCoupleVector.size();
          if(0 < n) {
            for(size_t i=0; i<fMaterialCutsCoupleVector.size(); ++i) {
              if(cutCouple == fMaterialCutsCoupleVector[i]) {
                break;
              }
            }
          }
          // initialise data banks
          fMaterialCutsCoupleVector.push_back(cutCouple);
          G4double deltaCutInKinEnergy = cuts[cutCouple->GetIndex()];
          fModelData->Initialise(cutCouple, deltaCutInKinEnergy, this);
        }
      }
    }
  }
}


void G4PAIModel::InitialiseLocal(const G4ParticleDefinition*, 
                                 G4VEmModel* masterModel)
{
  fModelData = static_cast<G4PAIModel*>(masterModel)->GetPAIModelData();
  SetElementSelectors(masterModel->GetElementSelectors());
}


G4double G4PAIModel::ComputeDEDXPerVolume(const G4Material*,
                                          const G4ParticleDefinition* p,
                                          G4double kineticEnergy,
                                          G4double cutEnergy)
{
  G4int coupleIndex = FindCoupleIndex(CurrentCouple());
  if(0 > coupleIndex) { return 0.0; }

  G4double cut = std::min(MaxSecondaryEnergy(p, kineticEnergy), cutEnergy);

  G4double scaledTkin = kineticEnergy*fRatio;
 
  return fChargeSquare*fModelData->DEDXPerVolume(coupleIndex, scaledTkin, cut);
}


G4double G4PAIModel::CrossSectionPerVolume( const G4Material*,
                                            const G4ParticleDefinition* p,
                                            G4double kineticEnergy,
                                            G4double cutEnergy,
                                            G4double maxEnergy  ) 
{
  G4int coupleIndex = FindCoupleIndex(CurrentCouple());
  if(0 > coupleIndex) { return 0.0; }

  G4double tmax = std::min(MaxSecondaryEnergy(p, kineticEnergy), maxEnergy);
  if(tmax <= cutEnergy) { return 0.0; }

  G4double scaledTkin = kineticEnergy*fRatio;

  return fChargeSquare*fModelData->CrossSectionPerVolume(coupleIndex, 
                                                         scaledTkin, 
                                                         cutEnergy, tmax);
}

//
// It is analog of PostStepDoIt in terms of secondary electron.
//
 
void G4PAIModel::SampleSecondaries(std::vector<G4DynamicParticle*>* vdp,
                                   const G4MaterialCutsCouple* matCC,
                                   const G4DynamicParticle* dp,
                                   G4double tmin,
                                   G4double maxEnergy)
{
  G4int coupleIndex = FindCoupleIndex(matCC);
  if(0 > coupleIndex) { return; }

  SetParticle(dp->GetDefinition());
  G4double kineticEnergy = dp->GetKineticEnergy();

  G4double tmax = MaxSecondaryEnergy(fParticle, kineticEnergy);
  if(maxEnergy < tmax) { tmax = maxEnergy; }
  if(tmin >= tmax) { return; }

  G4ThreeVector direction= dp->GetMomentumDirection();
  G4double scaledTkin    = kineticEnergy*fRatio;
  G4double totalEnergy   = kineticEnergy + fMass;
  G4double totalMomentum = sqrt(kineticEnergy*(totalEnergy+fMass));

  G4double deltaTkin = 
    fModelData->SamplePostStepTransfer(coupleIndex, scaledTkin);

  // G4cout<<"G4PAIModel::SampleSecondaries; deltaKIn = "<<deltaTkin/keV
  // <<" keV "<<G4endl;

  if( deltaTkin <= 0. && fVerbose > 0) 
  {
    G4cout<<"G4PAIModel::SampleSecondary e- deltaTkin = "<<deltaTkin<<G4endl;
  }
  if( deltaTkin <= 0.) { return; }

  if( deltaTkin > tmax) { deltaTkin = tmax; }

  const G4Element* anElement = SelectRandomAtom(matCC,fParticle,kineticEnergy);
  G4int Z = G4lrint(anElement->GetZ());
 
  G4DynamicParticle* deltaRay = new G4DynamicParticle(fElectron, 
            GetAngularDistribution()->SampleDirection(dp, deltaTkin,
                                                      Z, matCC->GetMaterial()),
                                                      deltaTkin);

  // primary change
  kineticEnergy -= deltaTkin;
  G4ThreeVector dir = totalMomentum*direction - deltaRay->GetMomentum();
  direction = dir.unit();
  fParticleChange->SetProposedKineticEnergy(kineticEnergy);
  fParticleChange->SetProposedMomentumDirection(direction);

  vdp->push_back(deltaRay);
}


G4double G4PAIModel::SampleFluctuations( const G4MaterialCutsCouple* matCC,
                                         const G4DynamicParticle* aParticle,
                                         G4double, G4double step,
                                         G4double eloss)
{
  G4int coupleIndex = FindCoupleIndex(matCC);
  if(0 > coupleIndex) { return eloss; }

  SetParticle(aParticle->GetDefinition());

  /*
  G4cout << "G4PAIModel::SampleFluctuations step(mm)= "<< step/mm
         << "  Eloss(keV)= " << eloss/keV  << " in " 
         << matCC->Getmaterial()->GetName() << G4endl;
  */

  G4double Tkin       = aParticle->GetKineticEnergy();
  G4double scaledTkin = Tkin*fRatio;

  G4double loss = fModelData->SampleAlongStepTransfer(coupleIndex, Tkin,
                                                      scaledTkin,
                                                      step*fChargeSquare);
  
  // G4cout<<"PAIModel AlongStepLoss = "<<loss/keV<<" keV, on step = "
  //<<step/mm<<" mm"<<G4endl; 
  return loss;

}

//
// Returns the statistical estimation of the energy loss distribution variance
//


G4double G4PAIModel::Dispersion( const G4Material* material, 
                                 const G4DynamicParticle* aParticle,
                                       G4double tmax, 
                                       G4double step       )
{
  G4double particleMass  = aParticle->GetMass();
  G4double electronDensity = material->GetElectronDensity();
  G4double kineticEnergy = aParticle->GetKineticEnergy();
  G4double q = aParticle->GetCharge()/eplus;
  G4double etot = kineticEnergy + particleMass;
  G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*particleMass)/(etot*etot);
  G4double siga  = (1.0/beta2 - 0.5) * twopi_mc2_rcl2 * tmax * step
                 * electronDensity * q * q;

  return siga;
  /*
  G4double loss, sumLoss=0., sumLoss2=0., sigma2, meanLoss=0.;
  for(G4int i = 0; i < fMeanNumber; i++)
  {
    loss      = SampleFluctuations(material,aParticle,tmax,step,meanLoss);
    sumLoss  += loss;
    sumLoss2 += loss*loss;
  }
  meanLoss = sumLoss/fMeanNumber;
  sigma2   = meanLoss*meanLoss + (sumLoss2-2*sumLoss*meanLoss)/fMeanNumber;
  return sigma2;
  */
}


G4double G4PAIModel::MaxSecondaryEnergy( const G4ParticleDefinition* p,
                                         G4double kinEnergy) 
{
  SetParticle(p);
  G4double tmax = kinEnergy;
  if(p == fElectron) { tmax *= 0.5; }
  else if(p != fPositron) { 
    G4double ratio= electron_mass_c2/fMass;
    G4double gamma= kinEnergy/fMass + 1.0;
    tmax = 2.0*electron_mass_c2*(gamma*gamma - 1.) /
                  (1. + 2.0*gamma*ratio + ratio*ratio);
  }
  return tmax;
}


void G4PAIModel::DefineForRegion(const G4Region* r) 
{
  fPAIRegionVector.push_back(r);
}

//
//