G4ParticleHPKallbachMannSyst.cc

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//
// neutron_hp -- source file
// J.P. Wellisch, Nov-1996
// A prototype of the low energy neutron transport model.
//
// 080801 Protect div0 error, when theCompundFraction is 1 by T. Koi
//
// P. Arce, June-2014 Conversion neutron_hp to particle_hp
//
// June-2019 - E. Mendoza --> perform some corrections
 
#include "G4ParticleHPKallbachMannSyst.hh"
 
#include "G4Exp.hh"
#include "G4HadronicException.hh"
#include "G4Log.hh"
#include "G4Pow.hh"
#include "G4SystemOfUnits.hh"
#include "Randomize.hh"
 
G4double G4ParticleHPKallbachMannSyst::Sample(G4double anEnergy)
{
  G4double result = 0.;
 
  G4double zero = GetKallbachZero(anEnergy);
  if (zero > 1) zero = 1.;
  if (zero < -1) zero = -1.;
  G4double max = Kallbach(zero, anEnergy);
  G4double upper = Kallbach(1., anEnergy);
  G4double lower = Kallbach(-1., anEnergy);
  if (upper > max) max = upper;
  if (lower > max) max = lower;
  G4double value, random;
 
  G4int icounter = 0;
  G4int icounter_max = 1024;
  do {
    icounter++;
    if (icounter > icounter_max) {
      G4cout << "Loop-counter exceeded the threshold value at " << __LINE__ << "th line of "
             << __FILE__ << "." << G4endl;
      break;
    }
    result = 2. * G4UniformRand() - 1;
    value = Kallbach(result, anEnergy) / max;
    random = G4UniformRand();
  } while (random > value);  // Loop checking, 11.05.2015, T. Koi
 
  return result;
}
 
G4double G4ParticleHPKallbachMannSyst::Kallbach(G4double cosTh, G4double anEnergy)
{
  // Kallbach-Mann systematics without normalization.
  G4double result;
  G4double theX = A(anEnergy) * cosTh;
  result =
    0.5 * (G4Exp(theX) * (1 + theCompoundFraction) + G4Exp(-theX) * (1 - theCompoundFraction));
  return result;
}
 
G4double G4ParticleHPKallbachMannSyst::GetKallbachZero(G4double anEnergy)
{
  G4double result;
  // delta 2.0e-16 in not good.
  // delta 4.0e-16 is OK
  // safety factor of 2
  G4double delta = 8.0e-16;
  if (std::abs(theCompoundFraction - 1) < delta) {
    theCompoundFraction = 1.0 - delta;
  }
  result = 0.5 * (1. / A(anEnergy)) * G4Log((1 - theCompoundFraction) / (1 + theCompoundFraction));
  return result;
}
 
G4double G4ParticleHPKallbachMannSyst::A(G4double anEnergy)
{
  G4double result;
  G4double C1 = 0.04 / MeV;
  G4double C2 = 1.8E-6 / (MeV * MeV * MeV);
  G4double C3 = 6.7E-7 / (MeV * MeV * MeV * MeV);
 
  G4double epsa = anEnergy * theTargetMass / (theTargetMass + theIncidentMass);
  G4int Ac = theTargetA + theProjectileA;
  G4int Nc = Ac - theTargetZ - theProjectileZ;
  G4int AA = theTargetA;
  G4int ZA = theTargetZ;
  G4double ea = epsa + SeparationEnergy(Ac, Nc, AA, ZA, theProjectileA, theProjectileZ);
  G4double Et1 = 130 * MeV;
  G4double R1 = std::min(ea, Et1);
  // theProductEnergy is still in CMS!!!
  G4double epsb = theProductEnergy * (theProductMass + theResidualMass) / theResidualMass;
  G4int AB = theResidualA;
  G4int ZB = theResidualZ;
  G4double eb = epsb + SeparationEnergy(Ac, Nc, AB, ZB, theProductA, theProductZ);
  G4double X1 = R1 * eb / ea;
  G4double Et3 = 41 * MeV;
  G4double R3 = std::min(ea, Et3);
  G4double X3 = R3 * eb / ea;
 
  G4double Ma = 1;
  G4double mb = 1;
  if (theProjectileA == 1 || (theProjectileZ == 1 && theProjectileA == 2)) {
    Ma = 1;
  }  // neutron,proton,deuteron
  else if (theProjectileA == 4 && theProjectileZ == 2) {
    Ma = 0;
  }  // alpha
  else if (theProjectileA == 3 && (theProjectileZ == 1 || theProjectileZ == 2)) {
    Ma = 0.5;
  }  // tritum,He3 : set intermediate value
  else {
    throw G4HadronicException(__FILE__, __LINE__,
                              "Severe error in the sampling of Kallbach-Mann Systematics");
  }
  if (theProductA == 1 && theProductZ == 0) {
    mb = 1. / 2.;
  }  // neutron
  else if (theProductA == 4 && theProductZ == 2) {
    mb = 2;
  }  // alpha
  else {
    mb = 1;
  }
 
  result = C1 * X1 + C2 * G4Pow::GetInstance()->powN(X1, 3)
           + C3 * Ma * mb * G4Pow::GetInstance()->powN(X3, 4);
  return result;
}
 
G4double G4ParticleHPKallbachMannSyst::SeparationEnergy(G4int Ac, G4int Nc, G4int AA, G4int ZA,
                                                        G4int Abinding, G4int Zbinding)
{
  G4double result;
  G4int NA = AA - ZA;
  G4int Zc = Ac - Nc;
  result = 15.68 * (Ac - AA);
  result += -28.07 * ((Nc - Zc) * (Nc - Zc) / (G4double)Ac - (NA - ZA) * (NA - ZA) / (G4double)AA);
  result +=
    -18.56 * (G4Pow::GetInstance()->A23(G4double(Ac)) - G4Pow::GetInstance()->A23(G4double(AA)));
  result += 33.22
            * ((Nc - Zc) * (Nc - Zc) / G4Pow::GetInstance()->powA(G4double(Ac), 4. / 3.)
               - (NA - ZA) * (NA - ZA) / G4Pow::GetInstance()->powA(G4double(AA), 4. / 3.));
  result += -0.717
            * (Zc * Zc / G4Pow::GetInstance()->A13(G4double(Ac))
               - ZA * ZA / G4Pow::GetInstance()->A13(G4double(AA)));
  result += 1.211 * (Zc * Zc / (G4double)Ac - ZA * ZA / (G4double)AA);
  G4double totalBinding(0);
  if (Zbinding == 0 && Abinding == 1) totalBinding = 0;
  if (Zbinding == 1 && Abinding == 1) totalBinding = 0;
  if (Zbinding == 1 && Abinding == 2) totalBinding = 2.224596;
  if (Zbinding == 1 && Abinding == 3) totalBinding = 8.481798;
  if (Zbinding == 2 && Abinding == 3) totalBinding = 7.718043;
  if (Zbinding == 2 && Abinding == 4) totalBinding = 28.29566;
  result += -totalBinding;
  result *= MeV;
  return result;
}