G4DNAUeharaScreenedRutherfordElasticModel.cc

Go to the documentation of this file.

//
// ********************************************************************
// * License and Disclaimer                                           *
// *                                                                  *
// * The  Geant4 software  is  copyright of the Copyright Holders  of *
// * the Geant4 Collaboration.  It is provided  under  the terms  and *
// * conditions of the Geant4 Software License,  included in the file *
// * LICENSE and available at  http://cern.ch/geant4/license .  These *
// * include a list of copyright holders.                             *
// *                                                                  *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work  make  any representation or  warranty, express or implied, *
// * regarding  this  software system or assume any liability for its *
// * use.  Please see the license in the file  LICENSE  and URL above *
// * for the full disclaimer and the limitation of liability.         *
// *                                                                  *
// * This  code  implementation is the result of  the  scientific and *
// * technical work of the GEANT4 collaboration.                      *
// * By using,  copying,  modifying or  distributing the software (or *
// * any work based  on the software)  you  agree  to acknowledge its *
// * use  in  resulting  scientific  publications,  and indicate your *
// * acceptance of all terms of the Geant4 Software license.          *
// ********************************************************************

#include "G4DNAUeharaScreenedRutherfordElasticModel.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4DNAMolecularMaterial.hh"

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....

using namespace std;

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....

G4DNAUeharaScreenedRutherfordElasticModel::G4DNAUeharaScreenedRutherfordElasticModel(const G4ParticleDefinition*,
                                                                                     const G4String& nam) :
    G4VEmModel(nam), isInitialised(false)
{
  //  nistwater = G4NistManager::Instance()->FindOrBuildMaterial("G4_WATER");
  fpWaterDensity = 0;

  killBelowEnergy = 9 * eV; // As in Geant4-DNA Screened Rutherford model
  lowEnergyLimit = 0 * eV;
  intermediateEnergyLimit = 200 * eV; // Switch between two final state models
  highEnergyLimit = 10 * keV;
  SetLowEnergyLimit(lowEnergyLimit);
  SetHighEnergyLimit(highEnergyLimit);

  verboseLevel = 0;
  // Verbosity scale:
  // 0 = nothing
  // 1 = warning for energy non-conservation
  // 2 = details of energy budget
  // 3 = calculation of cross sections, file openings, sampling of atoms
  // 4 = entering in methods

  if (verboseLevel > 0)
  {
    G4cout << "Screened Rutherford Elastic model is constructed " << G4endl<< "Energy range: "
    << lowEnergyLimit / eV << " eV - "
    << highEnergyLimit / MeV << " MeV"
    << G4endl;
  }
  fParticleChangeForGamma = 0;

  // Selection of computation method
  // We do not recommend "true" usage with the current cumul. proba. settings
  fasterCode = false;
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....

G4DNAUeharaScreenedRutherfordElasticModel::~G4DNAUeharaScreenedRutherfordElasticModel()
{
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....

void G4DNAUeharaScreenedRutherfordElasticModel::Initialise(const G4ParticleDefinition* /*particle*/,
                                                           const G4DataVector& /*cuts*/)
{

  if (verboseLevel > 3)
    G4cout << "Calling G4DNAUeharaScreenedRutherfordElasticModel::Initialise()"
        << G4endl;

    // Energy limits

    if (LowEnergyLimit() < lowEnergyLimit)
    {
      G4cout << "G4DNAUeharaScreenedRutherfordElasticModel: low energy limit increased from " <<
      LowEnergyLimit()/eV << " eV to " << lowEnergyLimit/eV << " eV" << G4endl;
      SetLowEnergyLimit(lowEnergyLimit);
    }

    if (HighEnergyLimit() > highEnergyLimit)
    {
      G4cout << "G4DNAUeharaScreenedRutherfordElasticModel: high energy limit decreased from " <<
      HighEnergyLimit()/MeV << " MeV to " << highEnergyLimit/MeV << " MeV" << G4endl;
      SetHighEnergyLimit(highEnergyLimit);
    }

    // Constants for final state by Brenner & Zaider
    // March 25th, 2014 - Vaclav Stepan, Sebastien Incerti
    // Added clear for MT 

    betaCoeff.clear();
    betaCoeff.push_back(7.51525);
    betaCoeff.push_back(-0.41912);
    betaCoeff.push_back(7.2017E-3);
    betaCoeff.push_back(-4.646E-5);
    betaCoeff.push_back(1.02897E-7);

    deltaCoeff.clear();
    deltaCoeff.push_back(2.9612);
    deltaCoeff.push_back(-0.26376);
    deltaCoeff.push_back(4.307E-3);
    deltaCoeff.push_back(-2.6895E-5);
    deltaCoeff.push_back(5.83505E-8);

    gamma035_10Coeff.clear();
    gamma035_10Coeff.push_back(-1.7013);
    gamma035_10Coeff.push_back(-1.48284);
    gamma035_10Coeff.push_back(0.6331);
    gamma035_10Coeff.push_back(-0.10911);
    gamma035_10Coeff.push_back(8.358E-3);
    gamma035_10Coeff.push_back(-2.388E-4);

    gamma10_100Coeff.clear();
    gamma10_100Coeff.push_back(-3.32517);
    gamma10_100Coeff.push_back(0.10996);
    gamma10_100Coeff.push_back(-4.5255E-3);
    gamma10_100Coeff.push_back(5.8372E-5);
    gamma10_100Coeff.push_back(-2.4659E-7);

    gamma100_200Coeff.clear();
    gamma100_200Coeff.push_back(2.4775E-2);
    gamma100_200Coeff.push_back(-2.96264E-5);
    gamma100_200Coeff.push_back(-1.20655E-7);

    //

    if( verboseLevel>0 )
    {
      G4cout << "Screened Rutherford elastic model is initialized " << G4endl
      << "Energy range: "
      << LowEnergyLimit() / eV << " eV - "
      << HighEnergyLimit() / MeV << " MeV"
      << G4endl;
    }

    // Initialize water density pointer
    fpWaterDensity = G4DNAMolecularMaterial::Instance()->GetNumMolPerVolTableFor(G4Material::GetMaterial("G4_WATER"));

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

  }

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....

G4double G4DNAUeharaScreenedRutherfordElasticModel::CrossSectionPerVolume(const G4Material* material,
                                                                          const G4ParticleDefinition* particleDefinition,
                                                                          G4double ekin,
                                                                          G4double,
                                                                          G4double)
{
  if (verboseLevel > 3)
  {
    G4cout
        << "Calling CrossSectionPerVolume() of G4DNAUeharaScreenedRutherfordElasticModel"
        << G4endl;
  }

  // Calculate total cross section for model

  G4double sigma=0;

  G4double waterDensity = (*fpWaterDensity)[material->GetIndex()];

  if(waterDensity!= 0.0)
  //if (material == nistwater || material->GetBaseMaterial() == nistwater)
  {

    if (ekin < highEnergyLimit)
    {
      if (ekin < killBelowEnergy) return DBL_MAX;

      G4double z = 7.42; // FROM PMB 37 (1992) 1841-1858 p1842
      G4double n = ScreeningFactor(ekin,z);
      G4double crossSection = RutherfordCrossSection(ekin, z);
      sigma = pi * crossSection / (n * (n + 1.));
    }

    if (verboseLevel > 2)
    {
      G4cout << "__________________________________" << G4endl;
      G4cout << "=== G4DNAUeharaScreenedRutherfordElasticModel - XS INFO START" << G4endl;
      G4cout << "=== Kinetic energy(eV)=" << ekin/eV << " particle : " << particleDefinition->GetParticleName() << G4endl;
      G4cout << "=== Cross section per water molecule (cm^2)=" << sigma/cm/cm << G4endl;
      G4cout << "=== Cross section per water molecule (cm^-1)=" << sigma*waterDensity/(1./cm) << G4endl;
      //      G4cout << " - Cross section per water molecule (cm^-1)=" << sigma*material->GetAtomicNumDensityVector()[1]/(1./cm) << G4endl;
      G4cout << "=== G4DNAUeharaScreenedRutherfordElasticModel - XS INFO END" << G4endl;
    }

  }

  return sigma*material->GetAtomicNumDensityVector()[1];
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

G4double G4DNAUeharaScreenedRutherfordElasticModel::RutherfordCrossSection(G4double k,
                                                                           G4double z)
{
  //
  //                               e^4         /      K + m_e c^2      \^2
  // sigma_Ruth(K) = Z (Z+1) -------------------- | --------------------- |
  //                          (4 pi epsilon_0)^2  \  K * (K + 2 m_e c^2)  /
  //
  // Where K is the electron non-relativistic kinetic energy
  //
  // NIM 155, pp. 145-156, 1978

  G4double length = (e_squared * (k + electron_mass_c2))
      / (4 * pi * epsilon0 * k * (k + 2 * electron_mass_c2));
  G4double cross = z * (z + 1) * length * length;

  return cross;
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

G4double G4DNAUeharaScreenedRutherfordElasticModel::ScreeningFactor(G4double k,
                                                                    G4double z)
{
  // From Phys Med Biol 37 (1992) 1841-1858
  // Z=7.42 for water

  const G4double constK(1.7E-5);

  G4double beta2;
  beta2 = 1. - 1. / ((1. + k / electron_mass_c2) * (1. + k / electron_mass_c2));

  G4double etaC;
  if (k < 50 * keV)
    etaC = 1.198;
  else
    etaC = 1.13 + 3.76 * (z * z / (137 * 137 * beta2));

  G4double numerator = etaC * constK * std::pow(z, 2. / 3.);

  k /= electron_mass_c2;

  G4double denominator = k * (2 + k);

  G4double value = 0.;
  if (denominator > 0.)
    value = numerator / denominator; // form 3

  return value;
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....

void G4DNAUeharaScreenedRutherfordElasticModel::SampleSecondaries(std::vector<
                                                                      G4DynamicParticle*>* /*fvect*/,
                                                                  const G4MaterialCutsCouple* /*couple*/,
                                                                  const G4DynamicParticle* aDynamicElectron,
                                                                  G4double,
                                                                  G4double)
{

  if (verboseLevel > 3)
  {
    G4cout
        << "Calling SampleSecondaries() of G4DNAUeharaScreenedRutherfordElasticModel"
        << G4endl;
  }

  G4double electronEnergy0 = aDynamicElectron->GetKineticEnergy();

  if (electronEnergy0 < killBelowEnergy)
  {
    fParticleChangeForGamma->SetProposedKineticEnergy(0.);
    fParticleChangeForGamma->ProposeTrackStatus(fStopAndKill);
    fParticleChangeForGamma->ProposeLocalEnergyDeposit(electronEnergy0);
    return;
  }

  G4double cosTheta = 0.;

  if (electronEnergy0>= killBelowEnergy && electronEnergy0 < highEnergyLimit)
  {
    if (electronEnergy0<intermediateEnergyLimit)
    {
      if (verboseLevel > 3) G4cout << "---> Using Brenner & Zaider model" << G4endl;
      cosTheta = BrennerZaiderRandomizeCosTheta(electronEnergy0);
    }

    if (electronEnergy0>=intermediateEnergyLimit)
    {
      if (verboseLevel > 3) G4cout << "---> Using Screened Rutherford model" << G4endl;
      G4double z = 7.42;  // FROM PMB 37 (1992) 1841-1858 p1842
      cosTheta = ScreenedRutherfordRandomizeCosTheta(electronEnergy0,z);
    }

    G4double phi = 2. * pi * G4UniformRand();

    G4ThreeVector zVers = aDynamicElectron->GetMomentumDirection();
    G4ThreeVector xVers = zVers.orthogonal();
    G4ThreeVector yVers = zVers.cross(xVers);

    G4double xDir = std::sqrt(1. - cosTheta*cosTheta);
    G4double yDir = xDir;
    xDir *= std::cos(phi);
    yDir *= std::sin(phi);

    G4ThreeVector zPrimeVers((xDir*xVers + yDir*yVers + cosTheta*zVers));

    fParticleChangeForGamma->ProposeMomentumDirection(zPrimeVers.unit());

    fParticleChangeForGamma->SetProposedKineticEnergy(electronEnergy0);
  }

}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....

G4double G4DNAUeharaScreenedRutherfordElasticModel::BrennerZaiderRandomizeCosTheta(G4double k)
{
  //  d sigma_el                         1                                 beta(K)
  // ------------ (K) ~ --------------------------------- + ---------------------------------
  //   d Omega           (1 + 2 gamma(K) - cos(theta))^2     (1 + 2 delta(K) + cos(theta))^2
  //
  // Maximum is < 1/(4 gamma(K)^2) + beta(K)/((2+2delta(K))^2)
  //
  // Phys. Med. Biol. 29 N.4 (1983) 443-447

  // gamma(K), beta(K) and delta(K) are polynomials with coefficients for energy measured in eV

  k /= eV;

  G4double beta = std::exp(CalculatePolynomial(k, betaCoeff));
  G4double delta = std::exp(CalculatePolynomial(k, deltaCoeff));
  G4double gamma;

  if (k > 100.)
  {
    gamma = CalculatePolynomial(k, gamma100_200Coeff);
    // Only in this case it is not the exponent of the polynomial
  } else
  {
    if (k > 10)
    {
      gamma = std::exp(CalculatePolynomial(k, gamma10_100Coeff));
    } else
    {
      gamma = std::exp(CalculatePolynomial(k, gamma035_10Coeff));
    }
  }

  // ***** Original method
  
  if (!fasterCode)
  {

  G4double oneOverMax = 1.
      / (1. / (4. * gamma * gamma)
          + beta / ((2. + 2. * delta) * (2. + 2. * delta)));

  G4double cosTheta = 0.;
  G4double leftDenominator = 0.;
  G4double rightDenominator = 0.;
  G4double fCosTheta = 0.;

  do
  {
    cosTheta = 2. * G4UniformRand()- 1.;

    leftDenominator = (1. + 2.*gamma - cosTheta);
    rightDenominator = (1. + 2.*delta + cosTheta);
    if ( (leftDenominator * rightDenominator) != 0. )
    {
      fCosTheta = oneOverMax * (1./(leftDenominator*leftDenominator) + beta/(rightDenominator*rightDenominator));
    }
  }
  while (fCosTheta < G4UniformRand());

  return cosTheta;
  }

  // ***** Alternative method using cumulative probability

  if (fasterCode)
  {
 
   G4double cosTheta = -1;
   G4double cumul = 0;
   G4double value = 0;
   G4double leftDenominator = 0.;
   G4double rightDenominator = 0.;

   // Number of integration steps in the -1,1 range
   G4int iMax=200;

   G4double random = G4UniformRand();

   // Cumulate differential cross section
   for (G4int i=0; i<iMax; i++)
   {
   cosTheta = -1 + i*2./(iMax-1);
   leftDenominator = (1. + 2.*gamma - cosTheta);
   rightDenominator = (1. + 2.*delta + cosTheta);
   if ( (leftDenominator * rightDenominator) != 0. )
   {
   cumul = cumul + (1./(leftDenominator*leftDenominator) + beta/(rightDenominator*rightDenominator));
   }
   }

   // Select cosTheta
   for (G4int i=0; i<iMax; i++)
   {
   cosTheta = -1 + i*2./(iMax-1);
   leftDenominator = (1. + 2.*gamma - cosTheta);
   rightDenominator = (1. + 2.*delta + cosTheta);
   if (cumul !=0 && (leftDenominator * rightDenominator) != 0.)
   value = value + (1./(leftDenominator*leftDenominator) + beta/(rightDenominator*rightDenominator)) / cumul;
   if (random < value) break;
   }

   return cosTheta;
  }
 
  return 0.;

}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

G4double G4DNAUeharaScreenedRutherfordElasticModel::CalculatePolynomial(G4double k,
                                                                        std::vector<
                                                                            G4double>& vec)
{
  // Sum_{i=0}^{size-1} vector_i k^i
  //
  // Phys. Med. Biol. 29 N.4 (1983) 443-447

  G4double result = 0.;
  size_t size = vec.size();

  while (size > 0)
  {
    size--;

    result *= k;
    result += vec[size];
  }

  return result;
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

G4double G4DNAUeharaScreenedRutherfordElasticModel::ScreenedRutherfordRandomizeCosTheta(G4double k,
                                                                                        G4double z)
{

  //  d sigma_el                sigma_Ruth(K)
  // ------------ (K) ~ -----------------------------
  //   d Omega           (1 + 2 n(K) - cos(theta))^2
  //
  // We extract cos(theta) distributed as (1 + 2 n(K) - cos(theta))^-2
  //
  // Maximum is for theta=0: 1/(4 n(K)^2) (When n(K) is positive, that is always satisfied within the validity of the process)
  //
  // Phys. Med. Biol. 45 (2000) 3171-3194

  // ***** Original method

  if (!fasterCode)
  {

   G4double n = ScreeningFactor(k, z);

   G4double oneOverMax = (4. * n * n);

   G4double cosTheta = 0.;
   G4double fCosTheta;

   do
   {
     cosTheta = 2. * G4UniformRand()- 1.;
     fCosTheta = (1 + 2.*n - cosTheta);
     if (fCosTheta !=0.) fCosTheta = oneOverMax / (fCosTheta*fCosTheta);
   }
   while (fCosTheta < G4UniformRand());

   return cosTheta;
  }

  // ***** Alternative method using cumulative probability
  if (fasterCode)
  {

   G4double cosTheta = -1;
   G4double cumul = 0;
   G4double value = 0;
   G4double n = ScreeningFactor(k, z);
   G4double fCosTheta;

   // Number of integration steps in the -1,1 range
   G4int iMax=200;

   G4double random = G4UniformRand();

   // Cumulate differential cross section
   for (G4int i=0; i<iMax; i++)
   {
   cosTheta = -1 + i*2./(iMax-1);
   fCosTheta = (1 + 2.*n - cosTheta);
   if (fCosTheta !=0.) cumul = cumul + 1./(fCosTheta*fCosTheta);
   }

   // Select cosTheta
   for (G4int i=0; i<iMax; i++)
   {
   cosTheta = -1 + i*2./(iMax-1);
   fCosTheta = (1 + 2.*n - cosTheta);
   if (cumul !=0.) value = value + (1./(fCosTheta*fCosTheta)) / cumul;
   if (random < value) break;
   }
   return cosTheta;
  }
 
  return 0.;
}