source: trunk/source/processes/electromagnetic/lowenergy/src/G4CrossSectionChargeIncreasePartial.cc@ 1229

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// $Id: G4CrossSectionChargeIncreasePartial.cc,v 1.3 2009/06/10 13:32:36 mantero Exp $
// GEANT4 tag $Name: geant4-09-03 $

#include "G4CrossSectionChargeIncreasePartial.hh"

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G4CrossSectionChargeIncreasePartial::G4CrossSectionChargeIncreasePartial()
{
  //ALPHA+

  f0[0][0]=1.;
  a0[0][0]=2.25;
  a1[0][0]=-0.75;
  b0[0][0]=-32.10;
  c0[0][0]=0.600;
  d0[0][0]=2.40;
  x0[0][0]=4.60;

  x1[0][0]=-1.;
  b1[0][0]=-1.;
   
  numberOfPartialCrossSections[0]=1;

  //HELIUM

  f0[0][1]=1.;
  a0[0][1]=2.25;
  a1[0][1]=-0.75;
  b0[0][1]=-30.93;
  c0[0][1]=0.590;
  d0[0][1]=2.35;
  x0[0][1]=4.29;

  f0[1][1]=1.;
  a0[1][1]=2.25;
  a1[1][1]=-0.75;
  b0[1][1]=-32.61;
  c0[1][1]=0.435;
  d0[1][1]=2.70;
  x0[1][1]=4.45;

  x1[0][1]=-1.;
  b1[0][1]=-1.;

  x1[1][1]=-1.;
  b1[1][1]=-1.;

  numberOfPartialCrossSections[1]=2;
}

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G4CrossSectionChargeIncreasePartial::~G4CrossSectionChargeIncreasePartial()
{}
 
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G4double G4CrossSectionChargeIncreasePartial::CrossSection(G4double k, G4int index, 
                                                           const G4ParticleDefinition* particleDefinition)
{

  G4int particleTypeIndex = 0;
  G4DNAGenericIonsManager *instance;
  instance = G4DNAGenericIonsManager::Instance();

  if (particleDefinition == instance->GetIon("alpha+")) particleTypeIndex=0;
  if (particleDefinition == instance->GetIon("helium")) particleTypeIndex=1;

  //
  // sigma(T) = f0 10 ^ y(log10(T/eV))
  //
  //         /  a0 x + b0                    x < x0
  //         |
  // y(x) = <   a0 x + b0 - c0 (x - x0)^d0   x0 <= x < x1
  //         |
  //         \  a1 x + b1                    x >= x1
  //
  //
  // f0, a0, a1, b0, b1, c0, d0, x0, x1 are parameters that change for protons and helium (0, +, ++)
  //
  // f0 has been added to the code in order to manage partial (shell-dependent) cross sections (if no shell dependence is present. f0=1. Sum of f0 over the considered shells should give 1)
  //
  // From Rad. Phys. and Chem. 59 (2000) 255-275, M. Dingfelder et al.
  // Inelastic-collision cross sections of liquid water for interactions of energetic proton
  //
  
  if (x1[index][particleTypeIndex]<x0[index][particleTypeIndex])
  {
      //
      // if x1 < x0 means that x1 and b1 will be calculated with the following formula (this piece of code is run on all alphas and not on protons)
      //
      // x1 = x0 + ((a0 - a1)/(c0 * d0)) ^ (1 / (d0 - 1))
      //
      // b1 = (a0 - a1) * x1 + b0 - c0 * (x1 - x0) ^ d0
      //
 
      x1[index][particleTypeIndex]=x0[index][particleTypeIndex] + std::pow((a0[index][particleTypeIndex] - a1[index][particleTypeIndex]) / (c0[index][particleTypeIndex] * d0[index][particleTypeIndex]), 1. / (d0[index][particleTypeIndex] - 1.));
      b1[index][particleTypeIndex]=(a0[index][particleTypeIndex] - a1[index][particleTypeIndex]) * x1[index][particleTypeIndex] + b0[index][particleTypeIndex] - c0[index][particleTypeIndex] * std::pow(x1[index][particleTypeIndex] - x0[index][particleTypeIndex], d0[index][particleTypeIndex]);
  }

  G4double x(std::log10(k/eV));
  G4double y;
  
  if (x<x0[index][particleTypeIndex])
    y=a0[index][particleTypeIndex] * x + b0[index][particleTypeIndex];
  else if (x<x1[index][particleTypeIndex])
    y=a0[index][particleTypeIndex] * x + b0[index][particleTypeIndex] - c0[index][particleTypeIndex] * std::pow(x - x0[index][particleTypeIndex], d0[index][particleTypeIndex]);
  else
    y=a1[index][particleTypeIndex] * x + b1[index][particleTypeIndex];

  return f0[index][particleTypeIndex] * std::pow(10., y)*m*m;
  
}

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G4int G4CrossSectionChargeIncreasePartial::RandomSelect(G4double k, 
                                                        const G4ParticleDefinition* particleDefinition)
{

  G4int particleTypeIndex = 0;
  G4DNAGenericIonsManager *instance;
  instance = G4DNAGenericIonsManager::Instance();

  if (particleDefinition == instance->GetIon("hydrogen")) return 0;
  if (particleDefinition == instance->GetIon("alpha+")) particleTypeIndex=0;
  if (particleDefinition == instance->GetIon("helium")) particleTypeIndex=1;

  const G4int n = numberOfPartialCrossSections[particleTypeIndex];
  G4double* values(new G4double[n]);
  G4double value = 0;
  G4int i = n;
  
  while (i>0)
  {
      i--;
      values[i]=CrossSection(k, i, particleDefinition);
      value+=values[i];
  }
  
  value*=G4UniformRand();
  
  i=n;
  while (i>0)
  {
      i--;
   
      if (values[i]>value)
        break;
  
      value-=values[i];
  }
  
  delete[] values;
  
  return i;
}

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G4double G4CrossSectionChargeIncreasePartial::Sum(G4double k, const G4ParticleDefinition* particleDefinition)
{
  G4int particleTypeIndex = 0;
  G4DNAGenericIonsManager *instance;
  instance = G4DNAGenericIonsManager::Instance();

  if (particleDefinition == instance->GetIon("alpha+")) particleTypeIndex=0;
  if (particleDefinition == instance->GetIon("helium")) particleTypeIndex=1;

  G4double totalCrossSection = 0.;

  for (G4int i=0; i<numberOfPartialCrossSections[particleTypeIndex]; i++)
  {
    totalCrossSection += CrossSection(k,i,particleDefinition);
  }
  return totalCrossSection;
}