G4BGGNucleonElasticXS.cc

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// $Id: G4BGGNucleonElasticXS.cc 78189 2013-12-04 16:34:08Z gcosmo $
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4BGGNucleonElasticXS
//
// Author:        Vladimir Ivanchenko
//
// Creation date: 13.03.2007
// Modifications:
//
//
// -------------------------------------------------------------------
//

#include "G4BGGNucleonElasticXS.hh"
#include "G4SystemOfUnits.hh"
#include "G4GlauberGribovCrossSection.hh"
#include "G4NucleonNuclearCrossSection.hh"
#include "G4HadronNucleonXsc.hh"
#include "G4ComponentSAIDTotalXS.hh"
#include "G4Proton.hh"
#include "G4Neutron.hh"
#include "G4NistManager.hh"
#include "G4Log.hh"
#include "G4Exp.hh"

#include "G4CrossSectionDataSetRegistry.hh"

const G4double llog10 = G4Log(10.);

G4BGGNucleonElasticXS::G4BGGNucleonElasticXS(const G4ParticleDefinition* p)
 : G4VCrossSectionDataSet("Barashenkov-Glauber") 
{
  verboseLevel = 0;
  fGlauberEnergy = 91.*GeV;
  fPDGEnergy = 5*GeV;
  fLowEnergy = 14.*MeV;
  fSAIDLowEnergyLimit = 1*MeV;
  fSAIDHighEnergyLimit = 1.3*GeV;
  fLowestXSection = millibarn;
  for (G4int i = 0; i < 93; ++i) {
    theGlauberFac[i] = 0.0;
    theCoulombFac[i] = 0.0;
    theA[i] = 1;
  }
  fNucleon = 0;
  fGlauber = 0;
  fHadron  = 0;
  fSAID    = 0;
  particle = p;
  theProton= G4Proton::Proton();
  isProton = false;
  isInitialized = false;
}

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G4BGGNucleonElasticXS::~G4BGGNucleonElasticXS()
{
  delete fHadron;
  delete fSAID;
}

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G4bool 
G4BGGNucleonElasticXS::IsElementApplicable(const G4DynamicParticle*, G4int,
                       const G4Material*)
{
  return true;
}

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G4bool G4BGGNucleonElasticXS::IsIsoApplicable(const G4DynamicParticle*, 
                          G4int Z, G4int,  
                          const G4Element*,
                          const G4Material*)
{
  return (1 == Z);
}

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

G4double
G4BGGNucleonElasticXS::GetElementCrossSection(const G4DynamicParticle* dp,
                          G4int ZZ, const G4Material*)
{
  // this method should be called only for Z > 1

  G4double cross = 0.0;
  G4double ekin = dp->GetKineticEnergy();
  G4int Z = ZZ;
  if(1 == Z) {
    cross = 1.0115*GetIsoCrossSection(dp,1,1);
  } else {
    if(Z > 92) { Z = 92; }

    if(ekin <= fLowEnergy) {
      cross = theCoulombFac[Z]*CoulombFactor(ekin, Z);

    } else if(ekin > fGlauberEnergy) {
      cross = theGlauberFac[Z]*fGlauber->GetElasticGlauberGribov(dp, Z, theA[Z]);
    } else {
      cross = fNucleon->GetElasticCrossSection(dp, Z);
    }
  }

  if(verboseLevel > 1) {
    G4cout << "G4BGGNucleonElasticXS::GetElementCrossSection  for "
       << dp->GetDefinition()->GetParticleName()
       << "  Ekin(GeV)= " << dp->GetKineticEnergy()/CLHEP::GeV
       << " in nucleus Z= " << Z << "  A= " << theA[Z]
       << " XS(b)= " << cross/barn 
       << G4endl;
  }
  //AR-04Dec2013  if(cross <= fLowestXSection) { cross = 0.0; }
  return cross;
}

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

G4double
G4BGGNucleonElasticXS::GetIsoCrossSection(const G4DynamicParticle* dp, 
                      G4int Z, G4int A, 
                      const G4Isotope*,
                      const G4Element*,
                      const G4Material*)
{
  // this method should be called only for Z = 1

  G4double cross = 0.0;
  G4double ekin = dp->GetKineticEnergy();

  if(ekin <= fSAIDLowEnergyLimit) {
    cross = theCoulombFac[0]*CoulombFactor(ekin, 1);
  } else if(ekin <= fSAIDHighEnergyLimit) {
    cross = fSAID->GetElasticIsotopeCrossSection(particle, ekin, 1, 1);
  } else if(ekin <= fPDGEnergy) {
    G4double cross1 = 
      fSAID->GetElasticIsotopeCrossSection(particle, fPDGEnergy, 1, 1);
    G4double cross2 = theCoulombFac[1]; 
    cross = cross1 + (cross2 - cross1)*(ekin - fSAIDHighEnergyLimit)
      /(fPDGEnergy - fSAIDHighEnergyLimit);
  } else {
    fHadron->GetHadronNucleonXscPDG(dp, theProton);
    cross = fHadron->GetElasticHadronNucleonXsc();
  } 
  cross *= A;

  if(verboseLevel > 1) {
    G4cout << "G4BGGNucleonElasticXS::GetIsoCrossSection  for "
       << dp->GetDefinition()->GetParticleName()
       << "  Ekin(GeV)= " << dp->GetKineticEnergy()/CLHEP::GeV
       << " in nucleus Z= " << Z << "  A= " << A
       << " XS(b)= " << cross/barn 
       << G4endl;
  }
  //AR-04Dec2013  if(cross <= fLowestXSection) { cross = 0.0; }
  return cross;
}

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

void G4BGGNucleonElasticXS::BuildPhysicsTable(const G4ParticleDefinition& p)
{
  if(&p == theProton || &p == G4Neutron::Neutron()) {
    particle = &p;

  } else {
    G4cout << "### G4BGGNucleonElasticXS WARNING: is not applicable to " 
       << p.GetParticleName()
       << G4endl;
    throw G4HadronicException(__FILE__, __LINE__,
      "G4BGGNucleonElasticXS::BuildPhysicsTable is used for wrong particle");
    return;
  }

  if(isInitialized) { return; }
  isInitialized = true;

  fNucleon = (G4NucleonNuclearCrossSection*)G4CrossSectionDataSetRegistry::Instance()->GetCrossSectionDataSet(G4NucleonNuclearCrossSection::Default_Name());
  fGlauber = (G4GlauberGribovCrossSection*)G4CrossSectionDataSetRegistry::Instance()->GetCrossSectionDataSet(G4GlauberGribovCrossSection::Default_Name());
    
  fHadron  = new G4HadronNucleonXsc();
  fSAID    = new G4ComponentSAIDTotalXS();
  fNucleon->BuildPhysicsTable(*particle);
  fGlauber->BuildPhysicsTable(*particle);
  if(particle == theProton) { 
    isProton = true; 
    fSAIDHighEnergyLimit = 3*GeV;
  }

  G4ParticleDefinition* part = const_cast<G4ParticleDefinition*>(particle);
  G4ThreeVector mom(0.0,0.0,1.0);
  G4DynamicParticle dp(part, mom, fGlauberEnergy);

  G4NistManager* nist = G4NistManager::Instance();

  G4double csup, csdn;
  G4int A;

  if(verboseLevel > 0) {
    G4cout << "### G4BGGNucleonElasticXS::Initialise for "
       << particle->GetParticleName() << G4endl;
  }

  for(G4int iz=2; iz<93; iz++) {

    A = G4lrint(nist->GetAtomicMassAmu(iz));
    theA[iz] = A;

    csup = fGlauber->GetElasticGlauberGribov(&dp, iz, A);
    csdn = fNucleon->GetElasticCrossSection(&dp, iz);

    theGlauberFac[iz] = csdn/csup;
    if(verboseLevel > 0) { 
      G4cout << "Z= " << iz <<  "  A= " << A 
         << " factor= " << theGlauberFac[iz] << G4endl;
    } 
  }

  theCoulombFac[0] = 
    fSAID->GetElasticIsotopeCrossSection(particle,fSAIDLowEnergyLimit,1,1)
    /CoulombFactor(fSAIDLowEnergyLimit, 1);

  dp.SetKineticEnergy(fPDGEnergy);
  fHadron->GetHadronNucleonXscPDG(&dp, theProton);
  theCoulombFac[1] = fHadron->GetElasticHadronNucleonXsc();

  if(verboseLevel > 0) {
    G4cout << "Z=1  A=1 " << " factor0= " << theCoulombFac[0] 
       << " factor1= " << theCoulombFac[1] 
       << G4endl; 
  }

  dp.SetKineticEnergy(fLowEnergy);
  for(G4int iz=2; iz<93; iz++) {
    theCoulombFac[iz] = 
      fNucleon->GetElasticCrossSection(&dp, iz)/CoulombFactor(fLowEnergy, iz);
    if(verboseLevel > 0) {
      G4cout << "Z= " << iz <<  "  A= " << theA[iz]
         << " factor= " << theCoulombFac[iz] << G4endl; 
    }
  }
}

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

G4double G4BGGNucleonElasticXS::CoulombFactor(G4double kinEnergy, G4int Z)
{
  G4double res= 1.0;
  
  // from G4ProtonInelasticCrossSection
  if(isProton) {

    if (Z <= 1) { return kinEnergy*kinEnergy; }

    G4double elog = G4Log(kinEnergy/GeV)/llog10;
    G4double aa = theA[Z];

    G4double ff1 = 5.6  - 0.016*aa;    // slope of the drop at medium energies.
    G4double ff2 = 1.37 + 1.37/aa;     // start of the slope.
    G4double ff3 = 0.8  + 18./aa - 0.002*aa;   // stephight
    res = 1.0 + ff3*(1.0 - (1.0/(1+G4Exp(-ff1*(elog + ff2)))));

    ff1 = 8.   - 8./aa  - 0.008*aa; // slope of the rise
    ff2 = 2.34 - 5.4/aa - 0.0028*aa; // start of the rise
    res /= (1.0 + G4Exp(-ff1*(elog + ff2)));

  } 
  return res;  
}

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void G4BGGNucleonElasticXS::CrossSectionDescription(std::ostream& outFile) const
{
  outFile << "The Barashenkov-Glauber-Gribov cross section handles elastic\n"
          << "scattering of protons and neutrons from nuclei using the\n"
          << "Barashenkov parameterization below 91 GeV and the Glauber-Gribov\n"
          << "parameterization above 91 GeV. n";
}

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