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// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4hIonEffChargeSquare
//
// Author:        V.Ivanchenko (Vladimir.Ivanchenko@cern.ch)
//
// Creation date: 20 July 2000
//
// Modifications:
// 20/07/2000  V.Ivanchenko First implementation
// 18/06/2001  V.Ivanchenko Continuation for eff.charge (small change of y)
// 08/10/2002  V.Ivanchenko The charge of the nucleus is used not charge of
//                          DynamicParticle
//
// Class Description:
//
// Ion effective charge model
// J.F.Ziegler and J.M.Manoyan, The stopping of ions in compaunds,
// Nucl. Inst. & Meth. in Phys. Res. B35 (1988) 215-228.
//
// Class Description: End
//
// -------------------------------------------------------------------
//
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....

#include "G4hIonEffChargeSquare.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4DynamicParticle.hh"
#include "G4ParticleDefinition.hh"
#include "G4Material.hh"
#include "G4Element.hh"
#include "G4Exp.hh"

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

G4hIonEffChargeSquare::G4hIonEffChargeSquare(const G4String& name)
  : G4VLowEnergyModel(name),
    theHeMassAMU(4.0026)
{;}

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

G4hIonEffChargeSquare::~G4hIonEffChargeSquare()
{;}

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

G4double G4hIonEffChargeSquare::TheValue(const G4DynamicParticle* particle,
                	                 const G4Material* material)
{
  G4double energy = particle->GetKineticEnergy() ;
  G4double particleMass = particle->GetMass() ;
  G4double charge = (particle->GetDefinition()->GetPDGCharge())/eplus ;

  G4double q = IonEffChargeSquare(material,energy,particleMass,charge) ;

  return q ;
}

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

G4double G4hIonEffChargeSquare::TheValue(const G4ParticleDefinition* aParticle,
       		                         const G4Material* material,
					 G4double kineticEnergy)
{
  //  SetRateMass(aParticle) ;
  G4double particleMass = aParticle->GetPDGMass() ;
  G4double charge = (aParticle->GetPDGCharge())/eplus ;

  G4double q = IonEffChargeSquare(material,kineticEnergy,particleMass,charge) ;

  return q ;
}

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

G4double G4hIonEffChargeSquare::HighEnergyLimit(
						const G4ParticleDefinition* ,
						const G4Material* ) const
{
  return 1.0*TeV ;
}

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

G4double G4hIonEffChargeSquare::LowEnergyLimit(
					       const G4ParticleDefinition* ,
					       const G4Material* ) const
{
  return 0.0 ;
}

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

G4double G4hIonEffChargeSquare::HighEnergyLimit(
						const G4ParticleDefinition* ) const
{
  return 1.0*TeV ;
}

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

G4double G4hIonEffChargeSquare::LowEnergyLimit(
					       const G4ParticleDefinition* ) const
{
  return 0.0 ;
}

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

G4bool G4hIonEffChargeSquare::IsInCharge(const G4DynamicParticle* ,
		                         const G4Material* ) const
{
  return true ;
}

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

G4bool G4hIonEffChargeSquare::IsInCharge(const G4ParticleDefinition* ,
      		                         const G4Material* ) const
{
  return true ;
}

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

G4double G4hIonEffChargeSquare::IonEffChargeSquare(
						   const G4Material* material,
						   G4double kineticEnergy,
						   G4double particleMass,
						   G4double ionCharge) const
{
  // The aproximation of ion effective charge from:
  // J.F.Ziegler, J.P. Biersack, U. Littmark
  // The Stopping and Range of Ions in Matter,
  // Vol.1, Pergamon Press, 1985

  // Fast ions or hadrons
  G4double reducedEnergy = kineticEnergy * proton_mass_c2/particleMass ;
  if(reducedEnergy < 1.0*keV) reducedEnergy = 1.0*keV;
  if( (reducedEnergy > ionCharge * 10.0 * MeV) ||
      (ionCharge < 1.5) ) return ionCharge*ionCharge ;

  static const G4double vFermi[92] = {
    1.0309,  0.15976, 0.59782, 1.0781,  1.0486,  1.0,     1.058,   0.93942, 0.74562, 0.3424,
    0.45259, 0.71074, 0.90519, 0.97411, 0.97184, 0.89852, 0.70827, 0.39816, 0.36552, 0.62712,
    0.81707, 0.9943,  1.1423,  1.2381,  1.1222,  0.92705, 1.0047,  1.2,     1.0661,  0.97411,
    0.84912, 0.95,    1.0903,  1.0429,  0.49715, 0.37755, 0.35211, 0.57801, 0.77773, 1.0207,
    1.029,   1.2542,  1.122,   1.1241,  1.0882,  1.2709,  1.2542,  0.90094, 0.74093, 0.86054,
    0.93155, 1.0047,  0.55379, 0.43289, 0.32636, 0.5131,  0.695,   0.72591, 0.71202, 0.67413,
    0.71418, 0.71453, 0.5911,  0.70263, 0.68049, 0.68203, 0.68121, 0.68532, 0.68715, 0.61884,
    0.71801, 0.83048, 1.1222,  1.2381,  1.045,   1.0733,  1.0953,  1.2381,  1.2879,  0.78654,
    0.66401, 0.84912, 0.88433, 0.80746, 0.43357, 0.41923, 0.43638, 0.51464, 0.73087, 0.81065,
    1.9578,  1.0257} ;

  static const G4double c[6] = {0.2865,  0.1266, -0.001429,
                          0.02402,-0.01135, 0.001475} ;

  // get elements in the actual material,
  const G4ElementVector* theElementVector = material->GetElementVector() ;
  const G4double* theAtomicNumDensityVector =
                         material->GetAtomicNumDensityVector() ;
  const G4int NumberOfElements = (G4int)material->GetNumberOfElements() ;

  //  loop for the elements in the material
  //  to find out average values Z, vF, lF
  G4double z = 0.0, vF = 0.0, norm = 0.0 ;

  if( 1 == NumberOfElements ) {
    z = material->GetZ() ;
    G4int iz = G4int(z) - 1 ;
    if(iz < 0) iz = 0 ;
    else if(iz > 91) iz = 91 ;
    vF   = vFermi[iz] ;

  } else {
    for (G4int iel=0; iel<NumberOfElements; iel++)
      {
        const G4Element* element = (*theElementVector)[iel] ;
        G4double z2 = element->GetZ() ;
        const G4double weight = theAtomicNumDensityVector[iel] ;
        norm += weight ;
        z    += z2 * weight ;
        G4int iz = G4int(z2) - 1 ;
        if(iz < 0) iz = 0 ;
        else if(iz > 91) iz =91 ;
        vF   += vFermi[iz] * weight ;
      }
    if (norm > 0.0) {
      z  /= norm ;
      vF /= norm ;
    }
  }

  // Helium ion case
  if( ionCharge < 2.5 ) {

    G4double e = std::log(std::max(1.0, kineticEnergy / (keV*theHeMassAMU) )) ;
    G4double x = c[0] ;
    G4double y = 1.0 ;
    for (G4int i=1; i<6; i++) {
      y *= e ;
      x += y * c[i] ;
    }
    G4double q = 7.6 -  e ;
    q = 1.0 + ( 0.007 + 0.00005 * z ) * G4Exp( -q*q ) ;
    return  4.0 * q * q * (1.0 - G4Exp(-x)) ;

    // Heavy ion case
  } else {

    // v1 is ion velocity in vF unit
    G4double v1{0.01}, v2{0.0};
    if (vF > 0.0) {
      v1 = std::sqrt( reducedEnergy / (25.0 * keV) )/ vF;
      v2 = 1.0/ (vF*vF);
    }
    G4double y ;
    G4double z13 = std::pow(ionCharge, 0.3333) ;

    // Faster than Fermi velocity
    if ( v1 > 1.0 ) {
      y = vF * v1 * ( 1.0 + 0.2 / (v1*v1) ) / (z13*z13) ;

      // Slower than Fermi velocity
    } else {
      y = 0.6923 * vF * (1.0 + 2.0*v1*v1/3.0 + v1*v1*v1*v1/15.0) / (z13*z13) ;
    }

    G4double y3 = std::pow(y, 0.3) ;
    G4double q = 1.0 - G4Exp( 0.803*y3 - 1.3167*y3*y3 -
                            0.38157*y - 0.008983*y*y ) ;
    if( q < 0.0 ) q = 0.0 ;

    G4double sLocal = 7.6 -  std::log(std::max(1.0, reducedEnergy/keV)) ;
    sLocal = 1.0 + ( 0.18 + 0.0015 * z ) * G4Exp( -sLocal*sLocal )/ (ionCharge*ionCharge) ;

    // Screen length according to
    // J.F.Ziegler and J.M.Manoyan, The stopping of ions in compaunds,
    // Nucl. Inst. & Meth. in Phys. Res. B35 (1988) 215-228.

    G4double lambda = 10.0 * vF * std::pow(1.0-q, 0.6667) / (z13 * (6.0 + q)) ;
    G4double qeff   = ionCharge * sLocal *
      ( q + 0.5*(1.0-q) * std::log(1.0 + lambda*lambda) * v2) ;
    if( 0.1 > qeff ) qeff = 0.1 ;
    return qeff*qeff ;
  }
}
