G4BGGPionElasticXS.cc

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// $Id$
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4BGGPionElasticXS
//
// Author:        Vladimir Ivanchenko
//
// Creation date: 01.10.2003
// Modifications:
//
// -------------------------------------------------------------------
//

#include "G4BGGPionElasticXS.hh"
#include "G4SystemOfUnits.hh"
#include "G4GlauberGribovCrossSection.hh"
#include "G4UPiNuclearCrossSection.hh"
#include "G4HadronNucleonXsc.hh"
#include "G4ComponentSAIDTotalXS.hh"
#include "G4Proton.hh"
#include "G4PionPlus.hh"
#include "G4PionMinus.hh"
#include "G4NistManager.hh"

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G4BGGPionElasticXS::G4BGGPionElasticXS(const G4ParticleDefinition*) 
 : G4VCrossSectionDataSet("Barashenkov-Glauber") 
{
  verboseLevel = 0;
  fGlauberEnergy = 91.*GeV;
  fLowEnergy = 20.*MeV;
  fSAIDHighEnergyLimit = 2.6*GeV;
  SetMinKinEnergy(0.0);
  SetMaxKinEnergy(100*TeV);

  for (G4int i = 0; i < 93; i++) {
    theGlauberFac[i] = 0.0;
    theCoulombFac[i] = 0.0;
    theA[i] = 1;
  }
  fPion = 0;
  fGlauber = 0;
  fHadron  = 0;
  fSAID    = 0;
  particle = 0;
  theProton= G4Proton::Proton();
  isPiplus = false;
  isInitialized = false;
}

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G4BGGPionElasticXS::~G4BGGPionElasticXS()
{
  delete fGlauber;
  delete fPion;
  delete fHadron;
  delete fSAID;
}

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G4bool 
G4BGGPionElasticXS::IsElementApplicable(const G4DynamicParticle*, G4int,
                                           const G4Material*)
{
  return true;
}

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

G4bool G4BGGPionElasticXS::IsIsoApplicable(const G4DynamicParticle*, 
                                              G4int Z, G4int A,  
                                              const G4Element*,
                                              const G4Material*)
{
  return (1 == Z && 2 >= A);
}

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

G4double
G4BGGPionElasticXS::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];
    } else if(ekin > fGlauberEnergy) {
      cross = theGlauberFac[Z]*fGlauber->GetElasticGlauberGribov(dp, Z, theA[Z]);
    } else {
      cross = fPion->GetElasticCrossSection(dp, Z, theA[Z]);
    }
  }
  if(verboseLevel > 1) {
    G4cout << "G4BGGPionElasticXS::GetElementCrossSection  for "
           << dp->GetDefinition()->GetParticleName()
           << "  Ekin(GeV)= " << dp->GetKineticEnergy()
           << " in nucleus Z= " << Z << "  A= " << theA[Z]
           << " XS(b)= " << cross/barn 
           << G4endl;
  }
  return cross;
}

G4double
G4BGGPionElasticXS::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 <= fSAIDHighEnergyLimit) {
    cross = fSAID->GetElasticIsotopeCrossSection(particle, ekin, 1, 1);
  } else {
    fHadron->GetHadronNucleonXscPDG(dp, theProton);
    cross = theCoulombFac[1]*fHadron->GetElasticHadronNucleonXsc();
  } 
  cross *= A;
  /*
  if(ekin <= fLowEnergy) {
    cross = theCoulombFac[1];

  } else if( A < 2) {
    fHadron->GetHadronNucleonXscNS(dp, G4Proton::Proton());
    cross = fHadron->GetElasticHadronNucleonXsc();
  } else {
    fHadron->GetHadronNucleonXscNS(dp, G4Proton::Proton());
    cross = fHadron->GetElasticHadronNucleonXsc();
    fHadron->GetHadronNucleonXscNS(dp, G4Neutron::Neutron());
    cross += fHadron->GetElasticHadronNucleonXsc();
  }
  */
  if(verboseLevel > 1) {
    G4cout << "G4BGGPionElasticXS::GetIsoCrossSection  for "
           << dp->GetDefinition()->GetParticleName()
           << "  Ekin(GeV)= " << dp->GetKineticEnergy()
           << " in nucleus Z= " << Z << "  A= " << A
           << " XS(b)= " << cross/barn 
           << G4endl;
  }
  return cross;
}

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

void G4BGGPionElasticXS::BuildPhysicsTable(const G4ParticleDefinition& p)
{
  if(&p == G4PionPlus::PionPlus() || &p == G4PionMinus::PionMinus()) {
    particle = &p;
  } else {
    G4cout << "### G4BGGPionElasticXS WARNING: is not applicable to " 
           << p.GetParticleName()
           << G4endl;
    throw G4HadronicException(__FILE__, __LINE__,
          "G4BGGPionElasticXS::BuildPhysicsTable is used for wrong particle");
    return;
  }

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

  fPion    = new G4UPiNuclearCrossSection();
  fGlauber = new G4GlauberGribovCrossSection();
  fHadron  = new G4HadronNucleonXsc();
  fSAID    = new G4ComponentSAIDTotalXS();
  fPion->BuildPhysicsTable(*particle);
  fGlauber->BuildPhysicsTable(*particle);
  if(particle == G4PionPlus::PionPlus()) { isPiplus = true; }

  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 << "### G4BGGPionElasticXS::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 = fPion->GetElasticCrossSection(&dp, iz, A);

    theGlauberFac[iz] = csdn/csup;
    if(verboseLevel > 0) {
      G4cout << "Z= " << iz <<  "  A= " << A 
             << " factor= " << theGlauberFac[iz] << G4endl; 
    }
  }
  /*
  dp.SetKineticEnergy(fLowEnergy);
  fHadron->GetHadronNucleonXscNS(&dp, G4Proton::Proton());
  theCoulombFac[1] = fHadron->GetElasticHadronNucleonXsc();
  */
  dp.SetKineticEnergy(fSAIDHighEnergyLimit);
  fHadron->GetHadronNucleonXscPDG(&dp, theProton);
  theCoulombFac[1] = 
    fSAID->GetElasticIsotopeCrossSection(particle,fSAIDHighEnergyLimit,1,1)
    /fHadron->GetElasticHadronNucleonXsc();

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

void
G4BGGPionElasticXS::CrossSectionDescription(std::ostream& outFile) const 
{
  outFile << "The Barashenkov-Glauber-Gribov cross section handles elastic\n"
          << "scattering of pions from nuclei at all energies. The\n"
          << "Barashenkov parameterization is used below 91 GeV and the\n"
          << "Glauber-Gribov parameterization is used above 91 GeV.\n";
}

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