G4BGGPionElasticXS.cc

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// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4BGGPionElasticXS
//
// Author:        Vladimir Ivanchenko
//
// Creation date: 01.10.2003
// Modifications:
//
// -------------------------------------------------------------------
//
 
#include "G4BGGPionElasticXS.hh"
#include "G4SystemOfUnits.hh"
#include "G4ComponentGGHadronNucleusXsc.hh"
#include "G4UPiNuclearCrossSection.hh"
#include "G4HadronNucleonXsc.hh"
#include "G4NuclearRadii.hh"
 
#include "G4Proton.hh"
#include "G4PionPlus.hh"
#include "G4PionMinus.hh"
#include "G4NistManager.hh"
#include "G4HadronicParameters.hh"
#include "G4Pow.hh"
 
G4double G4BGGPionElasticXS::theGlauberFacPiPlus[93] = {0.0};
G4double G4BGGPionElasticXS::theCoulombFacPiPlus[93] = {0.0};
G4double G4BGGPionElasticXS::theGlauberFacPiMinus[93] = {0.0};
G4double G4BGGPionElasticXS::theCoulombFacPiMinus[93] = {0.0};
G4int G4BGGPionElasticXS::theA[93] = {0};
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
G4BGGPionElasticXS::G4BGGPionElasticXS(const G4ParticleDefinition* p) 
 : G4VCrossSectionDataSet("BarashenkovGlauberGribov") 
{
  verboseLevel = 0;
  fGlauberEnergy = 91.*CLHEP::GeV;
  fLowEnergy = 20.*CLHEP::MeV;
  fLowestEnergy = 1.*CLHEP::MeV;
  SetMinKinEnergy(0.0);
  SetMaxKinEnergy( G4HadronicParameters::Instance()->GetMaxEnergy() );
 
  fPion    = new G4UPiNuclearCrossSection();
  fGlauber = new G4ComponentGGHadronNucleusXsc();
  fHadron  = new G4HadronNucleonXsc();
 
  fG4pow = G4Pow::GetInstance();
 
  theProton = G4Proton::Proton();
  thePiPlus = G4PionPlus::PionPlus();
  isPiplus = (p == thePiPlus);
  SetForAllAtomsAndEnergies(true);
 
  if (0 == theA[0]) { Initialise(); } 
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
G4BGGPionElasticXS::~G4BGGPionElasticXS()
{
  delete fHadron;
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
G4bool 
G4BGGPionElasticXS::IsElementApplicable(const G4DynamicParticle*, G4int,
                                        const G4Material*)
{
  return true;
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
G4bool G4BGGPionElasticXS::IsIsoApplicable(const G4DynamicParticle*, 
                                           G4int Z, G4int, 
                                           const G4Element*, const G4Material*)
{
  return (1 == Z);
}
 
//....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 = std::max(dp->GetKineticEnergy(), fLowestEnergy);
  G4int Z = std::min(ZZ, 92);
  if(1 == Z) {
    cross = 1.0115*GetIsoCrossSection(dp,1,1);
  } else {
    if(ekin <= fLowEnergy) {
      cross = (isPiplus) ? theCoulombFacPiPlus[Z]*CoulombFactorPiPlus(ekin, Z)
        : theCoulombFacPiMinus[Z]*FactorPiMinus(ekin);
    } else if(ekin > fGlauberEnergy) {
      cross = (isPiplus) ? theGlauberFacPiPlus[Z] : theGlauberFacPiMinus[Z];
      cross *= fGlauber->GetElasticGlauberGribov(dp, Z, theA[Z]);
    } else {
      cross = fPion->GetElasticCrossSection(dp, Z, theA[Z]);
    }
  }
#ifdef G4VERBOSE
  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;
  }
#endif
  return cross;
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
G4double
G4BGGPionElasticXS::GetIsoCrossSection(const G4DynamicParticle* dp, 
                                       G4int, G4int A, 
                                       const G4Isotope*,
                                       const G4Element*,
                                       const G4Material*)
{
  // this method should be called only for Z = 1
  fHadron->HadronNucleonXscNS(dp->GetDefinition(), theProton, 
                              dp->GetKineticEnergy());
  G4double cross = A*fHadron->GetElasticHadronNucleonXsc();
 
#ifdef G4VERBOSE
  if(verboseLevel > 1) {
    G4cout << "G4BGGPionElasticXS::GetIsoCrossSection  for "
           << dp->GetDefinition()->GetParticleName()
           << "  Ekin(GeV)= " << dp->GetKineticEnergy()
           << " in nucleus Z=1  A=" << A
           << " XS(b)= " << cross/barn 
           << G4endl;
  }
#endif
  return cross;
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
void G4BGGPionElasticXS::BuildPhysicsTable(const G4ParticleDefinition& p)
{
  if(verboseLevel > 1) {
    G4cout << "G4BGGPionElasticXS::BuildPhysicsTable for " 
           << p.GetParticleName() << G4endl;
  } 
  if(&p == G4PionPlus::PionPlus() || &p == G4PionMinus::PionMinus()) {
    isPiplus = (&p == G4PionPlus::PionPlus());
  } else {
    G4ExceptionDescription ed;
    ed << "This BGG cross section is applicable only to pions and not to " 
       << p.GetParticleName() << G4endl; 
    G4Exception("G4BGGPionElasticXS::BuildPhysicsTable", "had001", 
                FatalException, ed);
  }
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
void G4BGGPionElasticXS::Initialise()
{
  theA[0] = theA[1] = 1;
  G4ThreeVector mom(0.0,0.0,1.0);
  G4DynamicParticle dp(thePiPlus, mom, fGlauberEnergy);
 
  G4NistManager* nist = G4NistManager::Instance();
 
  G4double csup, csdn;
  for (G4int iz=2; iz<93; ++iz) {
 
    G4int A = G4lrint(nist->GetAtomicMassAmu(iz));
    theA[iz] = A;
 
    csup = fGlauber->GetElasticGlauberGribov(&dp, iz, A);
    csdn = fPion->GetElasticCrossSection(&dp, iz, A);
    theGlauberFacPiPlus[iz] = csdn/csup;
  }
 
  dp.SetDefinition(G4PionMinus::PionMinus());
  for (G4int iz=2; iz<93; ++iz) {
    csup = fGlauber->GetElasticGlauberGribov(&dp, iz, theA[iz]);
    csdn = fPion->GetElasticCrossSection(&dp, iz, theA[iz]);
    theGlauberFacPiMinus[iz] = csdn/csup;
 
    if (verboseLevel > 1) {
      G4cout << "Z= " << iz <<  "  A= " << theA[iz] 
         << " factorPiPlus= " << theGlauberFacPiPlus[iz] 
         << " factorPiMinus= " << theGlauberFacPiMinus[iz] 
         << G4endl; 
    }
  }
  theCoulombFacPiPlus[1] = 1.0;
  theCoulombFacPiMinus[1]= 1.0;
  dp.SetKineticEnergy(fLowEnergy);
  dp.SetDefinition(thePiPlus);
  for (G4int iz=2; iz<93; ++iz) {
    theCoulombFacPiPlus[iz] = fPion->GetElasticCrossSection(&dp, iz, theA[iz])
      /CoulombFactorPiPlus(fLowEnergy, iz);
  }
  dp.SetDefinition(G4PionMinus::PionMinus());
  for(G4int iz=2; iz<93; ++iz) {
    theCoulombFacPiMinus[iz] = fPion->GetElasticCrossSection(&dp, iz, theA[iz])
      /FactorPiMinus(fLowEnergy);
 
    if(verboseLevel > 1) {
      G4cout << "Z= " << iz <<  "  A= " << theA[iz] 
         << " CoulombFactorPiPlus= " << theCoulombFacPiPlus[iz] 
         << " CoulombFactorPiMinus= " << theCoulombFacPiMinus[iz] 
         << G4endl; 
    }
  }
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
G4double G4BGGPionElasticXS::CoulombFactorPiPlus(G4double kinEnergy, G4int Z)
{
  return (kinEnergy > 0.0) ? 
    G4NuclearRadii::CoulombFactor(Z, theA[Z], thePiPlus, kinEnergy) : 0.0;
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
G4double G4BGGPionElasticXS::FactorPiMinus(G4double kinEnergy)
{
  return 1.0/std::sqrt(kinEnergy);
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
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";
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......