G4PolarizedCompton.cc

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// $Id: G4PolarizedCompton.cc 69847 2013-05-16 09:36:18Z gcosmo $
// 
//
// File name:     G4PolarizedCompton
//
// Author:        Andreas Schaelicke
//                based on code by Michel Maire / Vladimir IVANTCHENKO
// Class description
//
// modified version respecting media and beam polarization
//     using the stokes formalism
//
// Creation date: 01.05.2005
//
// Modifications:
//
// 01-01-05, include polarization description (A.Stahl)
// 01-01-05, create asymmetry table and determine interactionlength (A.Stahl)
// 01-05-05, update handling of media polarization (A.Schalicke)
// 01-05-05, update polarized differential cross section (A.Schalicke)
// 20-05-05, added polarization transfer (A.Schalicke)
// 10-06-05, transformation between different reference frames (A.Schalicke)
// 17-10-05, correct reference frame dependence in GetMeanFreePath (A.Schalicke)
// 26-07-06, cross section recalculated (P.Starovoitov)
// 09-08-06, make it work under current geant4 release (A.Schalicke)
// 11-06-07, add PostStepGetPhysicalInteractionLength (A.Schalicke)
// -----------------------------------------------------------------------------


#include "G4PolarizedCompton.hh"
#include "G4SystemOfUnits.hh"
#include "G4Electron.hh"

#include "G4StokesVector.hh"
#include "G4PolarizationManager.hh"
#include "G4PolarizedComptonModel.hh"
#include "G4ProductionCutsTable.hh"
#include "G4PhysicsTableHelper.hh"
#include "G4KleinNishinaCompton.hh"
#include "G4PolarizedComptonModel.hh"

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G4PolarizedCompton::G4PolarizedCompton(const G4String& processName,
  G4ProcessType type):
  G4VEmProcess (processName, type),
  buildAsymmetryTable(true),
  useAsymmetryTable(true),
  isInitialised(false),
  selectedModel(0),
  mType(10),
  theAsymmetryTable(NULL)
{
  SetLambdaBinning(90);
  SetMinKinEnergy(0.1*keV);
  SetMaxKinEnergy(100.0*GeV);
  SetProcessSubType(fComptonScattering);
  emModel = 0;
}

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G4PolarizedCompton::~G4PolarizedCompton()
{
  if (theAsymmetryTable) {
    theAsymmetryTable->clearAndDestroy();
    delete theAsymmetryTable;
  }
}

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void G4PolarizedCompton::InitialiseProcess(const G4ParticleDefinition*)
{
  if(!isInitialised) {
    isInitialised = true;
    SetBuildTableFlag(true);
    SetSecondaryParticle(G4Electron::Electron());
    G4double emin = MinKinEnergy();
    G4double emax = MaxKinEnergy();
    emModel = new G4PolarizedComptonModel();
    if(0 == mType) selectedModel = new G4KleinNishinaCompton();
    else if(10 == mType) selectedModel = emModel;
    selectedModel->SetLowEnergyLimit(emin);
    selectedModel->SetHighEnergyLimit(emax);
    AddEmModel(1, selectedModel);
  } 
}

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void G4PolarizedCompton::PrintInfo()
{
  G4cout << " Total cross sections has a good parametrisation"
         << " from 10 KeV to (100/Z) GeV" 
         << "\n      Sampling according " << selectedModel->GetName() << " model" 
         << G4endl;
}         

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void G4PolarizedCompton::SetModel(const G4String& ss)
{
  if(ss == "Klein-Nishina") mType = 0;
  if(ss == "Polarized-Compton") mType = 10;
}


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



G4double G4PolarizedCompton::GetMeanFreePath(
                                   const G4Track& aTrack,
                                   G4double   previousStepSize,
                                   G4ForceCondition* condition)
{
  // *** get unploarised mean free path from lambda table ***
  G4double mfp = G4VEmProcess::GetMeanFreePath(aTrack, previousStepSize, condition);


   if (theAsymmetryTable && useAsymmetryTable) {
     // *** get asymmetry, if target is polarized ***
     const G4DynamicParticle* aDynamicGamma = aTrack.GetDynamicParticle();
     const G4double GammaEnergy = aDynamicGamma->GetKineticEnergy();
     const G4StokesVector GammaPolarization = aTrack.GetPolarization();
     const G4ParticleMomentum GammaDirection0 = aDynamicGamma->GetMomentumDirection();

     G4Material*         aMaterial = aTrack.GetMaterial();
     G4VPhysicalVolume*  aPVolume  = aTrack.GetVolume();
     G4LogicalVolume*    aLVolume  = aPVolume->GetLogicalVolume();

     //   G4Material* bMaterial = aLVolume->GetMaterial();
     G4PolarizationManager * polarizationManger = G4PolarizationManager::GetInstance();

     const G4bool VolumeIsPolarized = polarizationManger->IsPolarized(aLVolume);
     G4StokesVector ElectronPolarization = polarizationManger->GetVolumePolarization(aLVolume);

     if (!VolumeIsPolarized || mfp == DBL_MAX) return mfp;
     
     if (verboseLevel>=2) {

       G4cout << " Mom " << GammaDirection0  << G4endl;
       G4cout << " Polarization " << GammaPolarization  << G4endl;
       G4cout << " MaterialPol. " << ElectronPolarization  << G4endl;
       G4cout << " Phys. Volume " << aPVolume->GetName() << G4endl;
       G4cout << " Log. Volume  " << aLVolume->GetName() << G4endl;
       G4cout << " Material     " << aMaterial          << G4endl;
     }

     G4int midx= CurrentMaterialCutsCoupleIndex();
     G4PhysicsVector * aVector=(*theAsymmetryTable)(midx);
     
     G4double asymmetry=0;
     if (aVector) {
       G4bool isOutRange;
       asymmetry = aVector->GetValue(GammaEnergy, isOutRange);
     } else {
       G4cout << " MaterialIndex     " << midx << " is out of range \n";
       asymmetry=0;
     }

     //  we have to determine angle between particle motion 
     //  and target polarisation here  
     //      circ pol * Vec(ElectronPol)*Vec(PhotonMomentum)
     //  both vectors in global reference frame
     
     G4double pol=ElectronPolarization*GammaDirection0;
     
     G4double polProduct = GammaPolarization.p3() * pol;
     mfp *= 1. / ( 1. + polProduct * asymmetry );

     if (verboseLevel>=2) {
       G4cout << " MeanFreePath:  " << mfp / mm << " mm " << G4endl;
       G4cout << " Asymmetry:     " << asymmetry          << G4endl;
       G4cout << " PolProduct:    " << polProduct         << G4endl;
     }
   }

   return mfp;
}

G4double G4PolarizedCompton::PostStepGetPhysicalInteractionLength(
                                   const G4Track& aTrack,
                                   G4double   previousStepSize,
                                   G4ForceCondition* condition)
{
  // *** get unploarised mean free path from lambda table ***
  G4double mfp = G4VEmProcess::PostStepGetPhysicalInteractionLength(aTrack, previousStepSize, condition);


   if (theAsymmetryTable && useAsymmetryTable) {
     // *** get asymmetry, if target is polarized ***
     const G4DynamicParticle* aDynamicGamma = aTrack.GetDynamicParticle();
     const G4double GammaEnergy = aDynamicGamma->GetKineticEnergy();
     const G4StokesVector GammaPolarization = aTrack.GetPolarization();
     const G4ParticleMomentum GammaDirection0 = aDynamicGamma->GetMomentumDirection();

     G4Material*         aMaterial = aTrack.GetMaterial();
     G4VPhysicalVolume*  aPVolume  = aTrack.GetVolume();
     G4LogicalVolume*    aLVolume  = aPVolume->GetLogicalVolume();

     //   G4Material* bMaterial = aLVolume->GetMaterial();
     G4PolarizationManager * polarizationManger = G4PolarizationManager::GetInstance();

     const G4bool VolumeIsPolarized = polarizationManger->IsPolarized(aLVolume);
     G4StokesVector ElectronPolarization = polarizationManger->GetVolumePolarization(aLVolume);

     if (!VolumeIsPolarized || mfp == DBL_MAX) return mfp;
     
     if (verboseLevel>=2) {

       G4cout << " Mom " << GammaDirection0  << G4endl;
       G4cout << " Polarization " << GammaPolarization  << G4endl;
       G4cout << " MaterialPol. " << ElectronPolarization  << G4endl;
       G4cout << " Phys. Volume " << aPVolume->GetName() << G4endl;
       G4cout << " Log. Volume  " << aLVolume->GetName() << G4endl;
       G4cout << " Material     " << aMaterial          << G4endl;
     }

     G4int midx= CurrentMaterialCutsCoupleIndex();
     G4PhysicsVector * aVector=(*theAsymmetryTable)(midx);
     
     G4double asymmetry=0;
     if (aVector) {
       G4bool isOutRange;
       asymmetry = aVector->GetValue(GammaEnergy, isOutRange);
     } else {
       G4cout << " MaterialIndex     " << midx << " is out of range \n";
       asymmetry=0;
     }

     //  we have to determine angle between particle motion 
     //  and target polarisation here  
     //      circ pol * Vec(ElectronPol)*Vec(PhotonMomentum)
     //  both vectors in global reference frame
     
     G4double pol=ElectronPolarization*GammaDirection0;
     
     G4double polProduct = GammaPolarization.p3() * pol;
     mfp *= 1. / ( 1. + polProduct * asymmetry );

     if (verboseLevel>=2) {
       G4cout << " MeanFreePath:  " << mfp / mm << " mm " << G4endl;
       G4cout << " Asymmetry:     " << asymmetry          << G4endl;
       G4cout << " PolProduct:    " << polProduct         << G4endl;
     }
   }

   return mfp;
}

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

void G4PolarizedCompton::PreparePhysicsTable(const G4ParticleDefinition& part)
{
  G4VEmProcess::PreparePhysicsTable(part);
  if(buildAsymmetryTable)
    theAsymmetryTable = G4PhysicsTableHelper::PreparePhysicsTable(theAsymmetryTable);
}

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


void G4PolarizedCompton::BuildPhysicsTable(const G4ParticleDefinition& part)
{
  // *** build (unpolarized) cross section tables (Lambda)
  G4VEmProcess::BuildPhysicsTable(part);
  if(buildAsymmetryTable)
    BuildAsymmetryTable(part);
}

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void G4PolarizedCompton::BuildAsymmetryTable(const G4ParticleDefinition& part)
{
  // Access to materials
  const G4ProductionCutsTable* theCoupleTable=
        G4ProductionCutsTable::GetProductionCutsTable();
  size_t numOfCouples = theCoupleTable->GetTableSize();
  for(size_t i=0; i<numOfCouples; ++i) {
    if (!theAsymmetryTable) break;
    if (theAsymmetryTable->GetFlag(i)) {

      // create physics vector and fill it
      const G4MaterialCutsCouple* couple = theCoupleTable->GetMaterialCutsCouple(i);
      // use same parameters as for lambda
      G4PhysicsVector* aVector = LambdaPhysicsVector(couple);
      //      modelManager->FillLambdaVector(aVector, couple, startFromNull);

      for (G4int j = 0 ; j < LambdaBinning() ; ++j ) {
        G4double lowEdgeEnergy = aVector->GetLowEdgeEnergy(j);
        G4double tasm=0.;
        G4double asym = ComputeAsymmetry(lowEdgeEnergy, couple, part, 0., tasm);
        aVector->PutValue(j,asym);
      }

      G4PhysicsTableHelper::SetPhysicsVector(theAsymmetryTable, i, aVector);
    }
  }

}

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


G4double G4PolarizedCompton::ComputeAsymmetry(G4double energy,
                         const G4MaterialCutsCouple* couple,
                       const G4ParticleDefinition& aParticle,
                               G4double cut,
                               G4double & tAsymmetry)
{
  G4double lAsymmetry = 0.0;
  tAsymmetry=0;

  //
  // calculate polarized cross section
  //
  G4ThreeVector thePolarization=G4ThreeVector(0.,0.,1.);
  emModel->SetTargetPolarization(thePolarization);
  emModel->SetBeamPolarization(thePolarization);
  G4double sigma2=emModel->CrossSection(couple,&aParticle,energy,cut,energy);

  //
  // calculate unpolarized cross section
  //
  thePolarization=G4ThreeVector();
  emModel->SetTargetPolarization(thePolarization);
  emModel->SetBeamPolarization(thePolarization);
  G4double sigma0=emModel->CrossSection(couple,&aParticle,energy,cut,energy);

  // determine assymmetries
  if (sigma0>0.) {
    lAsymmetry=sigma2/sigma0-1.;
  }
  return lAsymmetry;
}

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