G4EmElementSelector Class Reference

#include <G4EmElementSelector.hh>

Public Member Functions
	G4EmElementSelector (G4VEmModel *, const G4Material *, G4int bins, G4double emin, G4double emax, G4bool spline=true)
	~G4EmElementSelector ()
void	Initialise (const G4ParticleDefinition *, G4double cut=0.0)
void	Dump (const G4ParticleDefinition *p=nullptr)
const G4Element *	SelectRandomAtom (G4double kineticEnergy) const
const G4Element *	SelectRandomAtom (const G4double kineticEnergy, const G4double logEKin) const
const G4Material *	GetMaterial () const

Detailed Description

Definition at line 62 of file G4EmElementSelector.hh.

Constructor & Destructor Documentation

G4EmElementSelector()

G4EmElementSelector::G4EmElementSelector	(	G4VEmModel *	mod,
		const G4Material *	mat,
		G4int	bins,
		G4double	emin,
		G4double	emax,
		G4bool	spline = true
	)

Definition at line 54 of file G4EmElementSelector.cc.

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

~G4EmElementSelector()

G4EmElementSelector::~G4EmElementSelector

(

)

Definition at line 85 of file G4EmElementSelector.cc.

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

Member Function Documentation

Dump()

void G4EmElementSelector::Dump

(

const G4ParticleDefinition *

p = nullptr

)

Definition at line 151 of file G4EmElementSelector.cc.

{
  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;
}

GetMaterial()

const G4Material * G4EmElementSelector::GetMaterial ( ) const

inline

Definition at line 160 of file G4EmElementSelector.hh.

{
  return material;
}

Initialise()

void G4EmElementSelector::Initialise	(	const G4ParticleDefinition *	part,
		G4double	cut = 0.0
	)

Definition at line 94 of file G4EmElementSelector.cc.

{
  //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() 
  //    << G4endl;
}

SelectRandomAtom() [1/2]

const G4Element * G4EmElementSelector::SelectRandomAtom ( const G4double  kineticEnergy, const G4double  logEKin  ) const

inline

Definition at line 125 of file G4EmElementSelector.hh.

{
  const G4Element* element = (*theElementVector)[nElmMinusOne];
  if (nElmMinusOne > 0) {
    // 1. Determine energy index (only once)
    const size_t nBins  = (xSections[0])->GetVectorLength();
    // handle cases below/above the enrgy grid (by ekin, idx that gives a=0/1)
    // ekin = x[0]   if e<=x[0]   and idx will be   0 ^ a=0 => so y=y0
    // ekin = x[N-1] if e>=x[N-1] and idx will be N-2 ^ a=1 => so y=y_{N-1}
    const G4double ekin = std::max((xSections[0])->Energy(0),
                                   std::min((xSections[0])->Energy(nBins-1),e));
    // compute the lower index of the bin (idx \in [0,N-2] will be guaranted)
    const size_t    idx = (xSections[0])->ComputeLogVectorBin(loge);
    // 2. Do the linear interp.(robust for corner cases through ekin, idx and a)
    const G4double   x1 = (xSections[0])->Energy(idx);
    const G4double   x2 = (xSections[0])->Energy(idx+1);
    // note: all corner cases of the previous methods are covered and eventually
    //       gives a=0/1 that results in y=y0\y_{N-1} if e<=x[0]/e>=x[N-1] or
    //       y=y_i/y_{i+1} if e<x[i]/e>=x[i+1] due to small numerical errors
    const G4double    a = std::max(0., std::min(1., (ekin - x1)/(x2 - x1)));
    const G4double urnd = G4UniformRand();
    for (G4int i = 0; i < nElmMinusOne; ++i) {
      const G4double  y1 = (*xSections[i])[idx];
      const G4double  y2 = (*xSections[i])[idx+1];
      if (urnd <= y1 + a*(y2-y1)) {
        element = (*theElementVector)[i];
        break;
      }
    }
  }
  return element;
}

SelectRandomAtom() [2/2]

const G4Element * G4EmElementSelector::SelectRandomAtom ( G4double  kineticEnergy ) const

inline

Definition at line 107 of file G4EmElementSelector.hh.

{
  const G4Element* element = (*theElementVector)[nElmMinusOne];
  if (nElmMinusOne > 0) {
    G4double x = G4UniformRand();
    size_t idx(0);
    for(G4int i=0; i<nElmMinusOne; ++i) {
      if (x <= (xSections[i])->Value(e, idx)) {
        element = (*theElementVector)[i];
        break;
      }
    }
  }
  return element;
}

---

The documentation for this class was generated from the following files:

• G4EmElementSelector.hh
• G4EmElementSelector.cc