G4EmElementSelector.cc

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// $Id$
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4EmElementSelector
//
// Author:        Vladimir Ivanchenko
//
// Creation date: 29.05.2008
//
// Modifications:
//
// Class Description:
//
// Generic helper class for the random selection of an element

// -------------------------------------------------------------------
//

#include "G4EmElementSelector.hh"
#include "G4VEmModel.hh"

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G4EmElementSelector::G4EmElementSelector(G4VEmModel* mod, 
                     const G4Material* mat, 
                     G4int bins, 
                     G4double emin, 
                     G4double emax,
                     G4bool spline):
  model(mod), material(mat), nbins(bins), cutEnergy(-1.0), 
  lowEnergy(emin), highEnergy(emax)
{
  G4int n = material->GetNumberOfElements();
  nElmMinusOne = n - 1;
  theElementVector = material->GetElementVector();
  element = (*theElementVector)[0];
  if(nElmMinusOne > 0) {
    xSections.reserve(n);
    G4PhysicsLogVector* v0 = new G4PhysicsLogVector(lowEnergy,highEnergy,nbins);
    xSections.push_back(v0);
    v0->SetSpline(spline);
    for(G4int i=1; i<n; ++i) {
      G4PhysicsLogVector* v = new G4PhysicsLogVector(*v0);
      xSections.push_back(v);
    }
  }
  //G4cout << "G4EmElementSelector for " << mat->GetName() << " n= " << n << G4endl;
}

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G4EmElementSelector::~G4EmElementSelector()
{
  if(nElmMinusOne > 0) {
    for(G4int i=0; i<=nElmMinusOne; ++i) {
      delete xSections[i];
    }
  }
}

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void G4EmElementSelector::Initialise(const G4ParticleDefinition* part, 
                     G4double cut)
{
  //G4cout << "G4EmElementSelector initialise for " << material->GetName() << G4endl;
  if(0 == nElmMinusOne || cut == cutEnergy) { return; }

  cutEnergy = cut;
  //G4cout << "cut(keV)= " << cut/keV << G4endl;
  G4double cross;

  const G4double* theAtomNumDensityVector = material->GetVecNbOfAtomsPerVolume();

  // loop over bins
  for(G4int j=0; j<=nbins; ++j) {
    G4double e = (xSections[0])->Energy(j);
    model->SetupForMaterial(part, material, e);
    cross = 0.0;
    //G4cout << "j= " << j << " e(MeV)= " << e/MeV << G4endl;
    for (G4int i=0; i<=nElmMinusOne; ++i) {
      cross += theAtomNumDensityVector[i]*      
    model->ComputeCrossSectionPerAtom(part, (*theElementVector)[i], e, 
                      cutEnergy, e);
      xSections[i]->PutValue(j, cross);
    }
  }

  // xSections start from null, so use probabilities from the next bin
  if(0.0 == (*xSections[nElmMinusOne])[0]) {
    for (G4int i=0; i<=nElmMinusOne; ++i) {
      xSections[i]->PutValue(0, (*xSections[i])[1]);
    }
  }
  // xSections ends with null, so use probabilities from the previous bin
  if(0.0 == (*xSections[nElmMinusOne])[nbins]) {
    for (G4int i=0; i<=nElmMinusOne; ++i) {
      xSections[i]->PutValue(nbins, (*xSections[i])[nbins-1]);
    }
  }
  // perform normalization
  for(G4int j=0; j<=nbins; ++j) {
    cross = (*xSections[nElmMinusOne])[j];
    // only for positive X-section 
    if(cross > 0.0) {
      for (G4int i=0; i<nElmMinusOne; ++i) {
        G4double x = (*xSections[i])[j]/cross;
    xSections[i]->PutValue(j, x);
      }
    }
  }
  //G4cout << "======== G4EmElementSelector for the " << model->GetName();
}

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void G4EmElementSelector::Dump(const G4ParticleDefinition* part)
{
  G4cout << "======== G4EmElementSelector for the " << model->GetName();
  if(part) G4cout << " and " << part->GetParticleName();
  G4cout << " for " << material->GetName() << " ========" << G4endl;
  if(0 < nElmMinusOne) {
    for(G4int i=0; i<nElmMinusOne; i++) {
      G4cout << "      " << (*theElementVector)[i]->GetName() << " : " << G4endl;
      G4cout << *(xSections[i]) << G4endl;
    }
  }  
  G4cout << "Last Element in element vector " 
     << (*theElementVector)[nElmMinusOne]->GetName() 
     << G4endl;
  G4cout << G4endl;
}

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