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/// \file G4LindhardPartition.cc
/// \brief Implementation of the G4LindhardPartition class

/*
 *  \file electromagnetic/TestEm7/src/G4LindhardPartition.cc
 *  \brief Implementation of the G4LindhardPartition class
 *
 *  Created by Marcus Mendenhall on 1/14/08.
 *  2008 Vanderbilt University, Nashville, TN, USA.
 *
 */

//

#include "G4LindhardPartition.hh"

#include "G4Element.hh"
#include "G4Material.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
/*
for a first cut, we will compute NIEL from a Lindhard-Robinson partition
based on the most abundant element in the material.

this is from IEEE Trans. Nucl Science Vol. 48 No.1 February 2001 page 162++
Insoo Jun, "Effects of Secondary Particles on the Total Dose..."
and, by reference,
Lindhard, Nielsen, Scharff & Thompson,
"Integral Equations Governing Radiation Efects...",
Mat. Fys. Medd. Dan. Vid. Selsk. vol 33 #10, pp1-42, 1963
and
Robinson, "The dependence of radiation effects on primary recoil energy",
in Proc. Int. Conf. Radiation-Induced Voids in Metal,
Albany, NY 1972 pp. 397-439
def lindhard_robinson(z1, a1, z2, a2, ke):
el=30.724*z1*z2*math.sqrt(z1**0.6667+z2**0.6667)*(a1+a2)/a2
fl=0.0793*z1**0.6667*math.sqrt(z2)*(a1+a2)**1.5/
((z1**0.6667+z2**0.6667)**0.75*a1**1.5*math.sqrt(a2))
eps=ke*(1.0/el)
return 1.0/(1+fl*(3.4008*eps**0.16667+0.40244*eps**0.75+eps))
*/

G4LindhardRobinsonPartition::G4LindhardRobinsonPartition()
{
  max_z = 120;
  for (size_t i = 1; i < max_z; i++) {
    z23[i] = std::pow((G4double)i, 2. / 3.);
  }
}

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

G4double G4LindhardRobinsonPartition::PartitionNIEL(G4int z1, G4double a1,
                                                    const G4Material* material,
                                                    G4double energy) const
{
  size_t nMatElements = material->GetNumberOfElements();

  const G4double* atomDensities = material->GetVecNbOfAtomsPerVolume();
  G4double maxdens = 0.0;
  size_t maxindex = 0;
  for (size_t k = 0; k < nMatElements; k++) {
    if (atomDensities[k] > maxdens) {
      maxdens = atomDensities[k];
      maxindex = k;
    }
  }
  const G4Element* element = material->GetElement(maxindex);

  G4int z2 = G4int(element->GetZ());

  G4double a2 = element->GetA() / (Avogadro * amu);

  G4double zpow = z23[z1] + z23[z2];
  G4double asum = a1 + a2;

  G4double el = 30.724 * z1 * z2 * std::sqrt(zpow) * asum / a2;
  G4double fl = 0.0793 * z23[z1] * std::sqrt(z2 * asum * asum * asum / (a1 * a1 * a1 * a2))
                / std::pow(zpow, 0.75);
  G4double eps = (energy / eV) * (1.0 / el);

  return 1.0 / (1 + fl * (3.4008 * std::pow(eps, 0.16667) + 0.40244 * std::pow(eps, 0.75) + eps));
}
