G4ParticleHPNBodyPhaseSpace.cc

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//
// P. Arce, June-2014 Conversion neutron_hp to particle_hp
//
#include "G4ParticleHPNBodyPhaseSpace.hh"
 
#include "G4Alpha.hh"
#include "G4Deuteron.hh"
#include "G4Electron.hh"
#include "G4Gamma.hh"
#include "G4He3.hh"
#include "G4Neutron.hh"
#include "G4PhysicalConstants.hh"
#include "G4Positron.hh"
#include "G4Proton.hh"
#include "G4ThreeVector.hh"
#include "G4Triton.hh"
#include "Randomize.hh"
 
G4ReactionProduct* G4ParticleHPNBodyPhaseSpace::Sample(G4double anEnergy, G4double massCode,
                                                       G4double)
{
  auto result = new G4ReactionProduct;
  auto Z = static_cast<G4int>(massCode / 1000);
  auto A = static_cast<G4int>(massCode - 1000 * Z);
 
  if (massCode == 0) {
    result->SetDefinition(G4Gamma::Gamma());
  }
  else if (A == 0) {
    result->SetDefinition(G4Electron::Electron());
    if (Z == 1) result->SetDefinition(G4Positron::Positron());
  }
  else if (A == 1) {
    result->SetDefinition(G4Neutron::Neutron());
    if (Z == 1) result->SetDefinition(G4Proton::Proton());
  }
  else if (A == 2) {
    result->SetDefinition(G4Deuteron::Deuteron());
  }
  else if (A == 3) {
    result->SetDefinition(G4Triton::Triton());
    if (Z == 2) result->SetDefinition(G4He3::He3());
  }
  else if (A == 4) {
    result->SetDefinition(G4Alpha::Alpha());
    if (Z != 2) throw G4HadronicException(__FILE__, __LINE__, "Unknown ion case 1");
  }
  else {
    throw G4HadronicException(__FILE__, __LINE__,
                              "G4ParticleHPNBodyPhaseSpace: Unknown ion case 2");
  }
 
  // Get the energy from phase-space distribution
  // in CMS
  // P = Cn*std::sqrt(E')*(Emax-E')**(3*n/2-4)
  G4double maxE = GetEmax(anEnergy, result->GetMass());
  if (maxE <= 0) {
    maxE = 1. * CLHEP::eV;
  }
  G4double energy = 0.;
  G4double max(0);
  if (theTotalCount <= 3) {
    max = maxE / 2.;
  }
  else if (theTotalCount == 4) {
    max = maxE / 5.;
  }
  else if (theTotalCount == 5) {
    max = maxE / 8.;
  }
  else {
    throw G4HadronicException(
      __FILE__, __LINE__,
      "NeutronHP Phase-space distribution cannot cope with this number of particles");
  }
  G4double testit;
  G4double rand0 = Prob(max, maxE, theTotalCount);
  G4double rand;
 
  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;
    }
    rand = rand0 * G4UniformRand();
    energy = maxE * G4UniformRand();
    testit = Prob(energy, maxE, theTotalCount);
  } while (rand > testit);  // Loop checking, 11.05.2015, T. Koi
  result->SetKineticEnergy(energy);
 
  // now do random direction
  G4double cosTh = 2. * G4UniformRand() - 1.;
  G4double phi = twopi * G4UniformRand();
  G4double theta = std::acos(cosTh);
  G4double sinth = std::sin(theta);
  G4double mtot = result->GetTotalMomentum();
  G4ThreeVector tempVector(mtot * sinth * std::cos(phi), mtot * sinth * std::sin(phi),
                           mtot * std::cos(theta));
  result->SetMomentum(tempVector);
  G4ReactionProduct aCMS = *GetTarget() + *GetProjectileRP();
  result->Lorentz(*result, -1. * aCMS);
  return result;
}