G4DensityEffectCalculator Class Reference

#include <G4DensityEffectCalculator.hh>

Public Member Functions
	G4DensityEffectCalculator (const G4Material *, G4int)
	~G4DensityEffectCalculator ()
G4double	ComputeDensityCorrection (G4double x)

Detailed Description

Definition at line 53 of file G4DensityEffectCalculator.hh.

Constructor & Destructor Documentation

G4DensityEffectCalculator()

G4DensityEffectCalculator::G4DensityEffectCalculator	(	const G4Material *	mat,
		G4int	n )

Definition at line 57 of file G4DensityEffectCalculator.cc.

  : fMaterial(mat), nlev(n)
{
  fVerbose = std::max(fVerbose, G4NistManager::Instance()->GetVerbose());
 
  sternf = new G4double[nlev];
  levE = new G4double[nlev];
  sternl = new G4double[nlev];
  sternEbar = new G4double[nlev];
  for (G4int i = 0; i < nlev; ++i) {
    sternf[i] = 0.0;
    levE[i] = 0.0;
    sternl[i] = 0.0;
    sternEbar[i] = 0.0;
  }
 
  fConductivity = sternx = 0.0;
  G4bool conductor = (fMaterial->GetFreeElectronDensity() > 0.0);
 
  G4int sh = 0;
  G4double sum = 0.;
  const G4double tot = fMaterial->GetTotNbOfAtomsPerVolume();
  for (size_t j = 0; j < fMaterial->GetNumberOfElements(); ++j) {
    // The last subshell is considered to contain the conduction
    // electrons. Sternheimer 1984 says "the lowest chemical valance of
    // the element" is used to set the number of conduction electrons.
    // I'm not sure if that means the highest subshell or the whole
    // shell, but in any case, he also says that the choice is arbitrary
    // and offers a possible alternative. This is one of the sources of
    // uncertainty in the model.
    const G4double frac = fMaterial->GetVecNbOfAtomsPerVolume()[j] / tot;
    const G4int Z = fMaterial->GetElement((G4int)j)->GetZasInt();
    const G4int nshell = G4AtomicShells::GetNumberOfShells(Z);
    for (G4int i = 0; i < nshell; ++i) {
      // For conductors, put *all* top shell electrons into the conduction
      // band, regardless of element.
      const G4double xx = frac * G4AtomicShells::GetNumberOfElectrons(Z, i);
      if (i < nshell - 1 || ! conductor) {
        sternf[sh] += xx;
      }
      else {
        fConductivity += xx;
      }
      levE[sh] = G4AtomicShells::GetBindingEnergy(Z, i) / CLHEP::eV;
      ++sh;
    }
  }
  for (G4int i = 0; i < nlev; ++i) {
    sum += sternf[i];
  }
  sum += fConductivity;
 
  const G4double invsum = (sum > 0.0) ? 1. / sum : 0.0;
  for (G4int i = 0; i < nlev; ++i) {
    sternf[i] *= invsum;
  }
  fConductivity *= invsum;
  plasmaE = fMaterial->GetIonisation()->GetPlasmaEnergy() / CLHEP::eV;
  meanexcite = fMaterial->GetIonisation()->GetMeanExcitationEnergy() / CLHEP::eV;
}

~G4DensityEffectCalculator()

G4DensityEffectCalculator::~G4DensityEffectCalculator

(

)

Definition at line 118 of file G4DensityEffectCalculator.cc.

{
  delete[] sternf;
  delete[] levE;
  delete[] sternl;
  delete[] sternEbar;
}

Member Function Documentation

ComputeDensityCorrection()

G4double G4DensityEffectCalculator::ComputeDensityCorrection

(

G4double

x

)

Definition at line 126 of file G4DensityEffectCalculator.cc.

{
  if (fVerbose > 1) {
    G4cout << "G4DensityEffectCalculator::ComputeDensityCorrection for " << fMaterial->GetName()
           << ", x= " << x << G4endl;
  }
  const G4double approx = fMaterial->GetIonisation()->GetDensityCorrection(x);
  const G4double exact = FermiDeltaCalculation(x);
 
  if (fVerbose > 1) {
    G4cout << "   Delta: computed= " << exact << ", parametrized= " << approx << G4endl;
  }
  if (approx >= 0. && exact < 0.) {
    if (fVerbose > 0) {
      ++fWarnings;
      if (fWarnings < maxWarnings) {
        G4ExceptionDescription ed;
        ed << "Sternheimer fit failed for " << fMaterial->GetName() << ", x = " << x
           << ": Delta exact= " << exact << ", approx= " << approx;
        G4Exception("G4DensityEffectCalculator::DensityCorrection", "mat008", JustWarning, ed);
      }
    }
    return approx;
  }
  // Fall back to approx if exact and approx are very different, under the
  // assumption that this means the exact calculation has gone haywire
  // somehow, with the exception of the case where approx is negative.  I
  // have seen this clearly-wrong result occur for substances with extremely
  // low density (1e-25 g/cc).
  if (approx >= 0. && std::abs(exact - approx) > 1.) {
    if (fVerbose > 0) {
      ++fWarnings;
      if (fWarnings < maxWarnings) {
        G4ExceptionDescription ed;
        ed << "Sternheimer exact= " << exact << " and approx= " << approx
           << " are too different for " << fMaterial->GetName() << ", x = " << x;
        G4Exception("G4DensityEffectCalculator::DensityCorrection", "mat008", JustWarning, ed);
      }
    }
    return approx;
  }
  return exact;
}

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

• G4DensityEffectCalculator.hh
• G4DensityEffectCalculator.cc