G4BertiniEvaporation.cc

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//
//
// Implementation of the HETC88 code into Geant4.
// Evaporation and De-excitation parts
// T. Lampen, Helsinki Institute of Physics, May-2000

#include "globals.hh"
#include "G4BertiniEvaporation.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4BENeutronChannel.hh"
#include "G4BEProtonChannel.hh"
#include "G4BEDeuteronChannel.hh"
#include "G4BETritonChannel.hh"
#include "G4BEHe3Channel.hh"
#include "G4BEHe4Channel.hh"
#include "G4BEGammaDeexcitation.hh"

// verboseLevels : 4 inform about basic probabilities and branchings
//                 6 some details about calculations
//                 8 inform about final values
//                10 inform everything

G4BertiniEvaporation::G4BertiniEvaporation()
{
    G4cout << "Info G4BertiniEvaporation: This is still very fresh code."<< G4endl;
    G4cout << "     G4BertiniEvaporation: feed-back for improvement is very wellcome."<< G4endl;
    verboseLevel = 0;
 
    channelVector.push_back( new G4BENeutronChannel );
    channelVector.push_back( new G4BEProtonChannel  );
    channelVector.push_back( new G4BEDeuteronChannel);
    channelVector.push_back( new G4BETritonChannel  );
    channelVector.push_back( new G4BEHe3Channel     );
    channelVector.push_back( new G4BEHe4Channel     );
}


G4BertiniEvaporation::~G4BertiniEvaporation()
{
  while ( !channelVector.empty() )
    {
      delete channelVector.back();
      channelVector.pop_back();
    }
}


void G4BertiniEvaporation::setVerboseLevel( const G4int verbose )
{
  verboseLevel = verbose;

  // Update verbose level to all evaporation channels.
  std::vector< G4BertiniEvaporationChannel * >::iterator iChannel = channelVector.begin();  
  for ( ; iChannel != channelVector.end() ; *iChannel++ )                  
    ( *iChannel )->setVerboseLevel( verboseLevel );
}


G4FragmentVector * G4BertiniEvaporation::BreakItUp( G4LayeredNucleus & nucleus )
{
  G4int nucleusA;
  G4int nucleusZ;
  G4int i;
  G4double totalProbability;
  G4double excE;
  G4double newExcitation;
  G4double nucleusTotalMomentum;
  G4double nucleusKineticEnergy;
  G4double mRes; // Mass of residual nucleus.
  G4ThreeVector nucleusMomentumVector;
  G4DynamicParticle *pEmittedParticle;
  std::vector< G4DynamicParticle * > secondaryParticleVector;
  G4FragmentVector * result = new G4FragmentVector;
  
  // Read properties of the nucleus.
  nucleusA = nucleus.GetA_asInt();
  nucleusZ = nucleus.GetZ_asInt();
  excE                  = nucleus.GetEnergyDeposit();
  nucleusMomentumVector = nucleus.GetMomentum();

  // Move to CMS frame, save initial velocity of the nucleus to boostToLab vector.
  G4ThreeVector boostToLab( ( 1/G4NucleiProperties::GetNuclearMass( nucleusA, nucleusZ ) ) 
                            * nucleusMomentumVector ); // xx mass ok?

  if ( verboseLevel >= 10 )
    G4cout << " G4BertiniEvaporation : initial kinematics : boostToLab vector = " << boostToLab << G4endl
           << "                     excitation energy  : " << excE<< G4endl;

  if ( nucleusA == 8 && nucleusZ == 4 )
    {
      splitBe8( excE, boostToLab, secondaryParticleVector );
      fillResult( secondaryParticleVector, result);
      return result;
    }
  
  // Initialize evaporation channels and calculate sum of emission
  // probabilities.
  std::vector< G4BertiniEvaporationChannel * >::iterator iChannel = channelVector.begin();  
  totalProbability = 0;
  for ( ; iChannel != channelVector.end() ; *iChannel++ )                  
     {
       ( *iChannel )->setNucleusA( nucleusA );
       ( *iChannel )->setNucleusZ( nucleusZ );
       ( *iChannel )->setExcitationEnergy( excE );
       ( *iChannel )->setPairingCorrection( 1 );
       ( *iChannel )->calculateProbability();
       totalProbability += ( *iChannel )->getProbability();
     }

  // If no evaporation process is possible, try without pairing energy.
  if ( totalProbability == 0 )
    {
      if ( verboseLevel >= 4 )
        G4cout << "G4BertiniEvaporation : no emission possible with pairing correction, trying without it" << G4endl;
      for ( iChannel = channelVector.begin() ; iChannel != channelVector.end() ; *iChannel++ )
        {
          ( *iChannel )->setPairingCorrection(0);
          ( *iChannel )->calculateProbability();
          totalProbability += ( *iChannel )->getProbability();
        }
      if ( verboseLevel >= 4 )
        G4cout << "                       probability without correction " << totalProbability << G4endl;

    }

  // Normal evaporation cycle follows.
  // Particles are evaporated till all probabilities are zero.
  while ( totalProbability > 0 )
    {
      G4BertiniEvaporationChannel *pSelectedChannel;

      // Sample active emission channel.
      G4double sampledProbability = G4UniformRand() * totalProbability;
      if ( verboseLevel >= 10 ) G4cout << "          RandomProb : " << sampledProbability << G4endl;
      for ( iChannel = channelVector.begin() ; iChannel != channelVector.end() ; *iChannel++ )
        {
          sampledProbability -= ( *iChannel )->getProbability();
          if ( sampledProbability < 0 ) break;
        }
      pSelectedChannel = ( *iChannel );
      if ( iChannel == channelVector.end() )
        throw G4HadronicException(__FILE__, __LINE__,  "G4BertiniEvaporation : Error while sampling evaporation particle" );

      if ( verboseLevel >= 4 ) 
        G4cout << "G4BertiniEvaporation : particle " << pSelectedChannel->getName() << " selected " << G4endl;

      // Max 10 tries to get a physically acceptable particle energy
      // in this emission channel.
      i = 0;

      do
        {
          pEmittedParticle = pSelectedChannel->emit();
          // This loop checks that particle with too large energy is not emitted.
          // CMS frame is considered in this loop. Nonrelativistic treatment. xxx


          const G4int zRes = nucleusZ - pSelectedChannel->getParticleZ(); 
          const G4int aRes  = nucleusA - pSelectedChannel->getParticleA(); 
          // const G4double eBind = G4NucleiProperties::GetBindingEnergy( aRes, zRes );  // Binding energy of the nucleus.
          mRes  = G4NucleiProperties::GetNuclearMass( aRes, zRes ); // Mass of the target nucleus
          //      In HETC88:
          //      eBind = Z * (-0.78244) + A * 8.36755 - cameron ( A , Z );
          //      mRes =  zRes * 938.79304 + ( aRes - zRes ) * 939.57548 - eBind; 
          //      where cameron ( A, Z ) is the mass excess by Cameron, see Canadian Journal of Physics,
          //      vol. 35, 1957, p.1022

          nucleusTotalMomentum = pEmittedParticle->GetTotalMomentum(); // CMS frame
          nucleusKineticEnergy = std::pow( nucleusTotalMomentum, 2 ) / ( 2 * mRes );
          newExcitation = excE - pEmittedParticle->GetKineticEnergy() - nucleusKineticEnergy - pSelectedChannel->getQ();

          if ( verboseLevel >= 10)
            G4cout << "G4BertiniEvaporation : Kinematics " << G4endl
                   << "                    part kinetic E in CMS = " 
                   << pEmittedParticle->GetKineticEnergy() << G4endl
                   << "                    new excitation E      =  " 
                   << newExcitation << G4endl;

          i++;
          if ( !( newExcitation > 0 ) && i < 10) delete pEmittedParticle;
        } while ( !( newExcitation > 0 )  &&  i < 10 );

      if ( i >= 10 ) 
        {
          // No appropriate particle energy found.
          // Set probability of this channel to zero 
          // and try to sample another particle on the 
          // next round.
          delete pEmittedParticle;

          if ( verboseLevel >= 4 )
            G4cout << "G4BertiniEvaporation : No appropriate energy for particle " 
                   << pSelectedChannel->getName() << " found." << G4endl;

          pSelectedChannel->setProbability( 0 );

          totalProbability = 0;
          for ( ; iChannel != channelVector.end() ; *iChannel++ )                  
            totalProbability += ( *iChannel )->getProbability();
        } // Treatment of physically unacceptable particle ends.
      else
        {
          // Good particle found. 

          // Transform particle properties to lab frame and save it.
          G4LorentzVector particleFourVector = pEmittedParticle->Get4Momentum();
          G4LorentzVector nucleusFourVector(  - pEmittedParticle->GetMomentum(), // CMS Frame.
                                              nucleusKineticEnergy + mRes ); // Total energy.
          particleFourVector.boost( boostToLab );
          nucleusFourVector.boost(  boostToLab );
          G4DynamicParticle *pPartLab  = new G4DynamicParticle( pEmittedParticle->GetDefinition(),
                                                                particleFourVector.e(), // Total energy
                                                                particleFourVector.vect() ); // momentum vector
          secondaryParticleVector.push_back( pPartLab );

          // Update residual nucleus and boostToLab vector.
          nucleusA = nucleusA - pSelectedChannel->getParticleA();
          nucleusZ = nucleusZ - pSelectedChannel->getParticleZ();
          excE = newExcitation;
          boostToLab = G4ThreeVector ( ( 1/mRes ) * nucleusFourVector.vect() );

          if ( verboseLevel >= 10 )
            G4cout << "  particle mom in cms " << pEmittedParticle->GetMomentum() << G4endl 
                   << "  particle mom in cms " << pEmittedParticle->GetTotalMomentum() << G4endl 
                   << "          Etot in cms " << pEmittedParticle->GetTotalEnergy() << G4endl
                   << "          Ekin in cms " << pEmittedParticle->GetKineticEnergy() << G4endl
                   << "        particle mass " << pEmittedParticle->GetMass() << G4endl
                   << "          boost  vect " << boostToLab << G4endl
                   << "          boosted 4v  " << particleFourVector << G4endl
                   << "          nucleus 4v  " << nucleusFourVector << G4endl
                   << "          nucl cm mom " << nucleusTotalMomentum << G4endl
                   << " particle k.e. in lab " << pPartLab->GetKineticEnergy() << G4endl
                   << "     new boost vector " << boostToLab << G4endl;

          delete pEmittedParticle;

          // If the residual nucleus is Be8, split it.
          if ( nucleusA == 8 && nucleusZ == 4 )
            {
              splitBe8( excE, boostToLab, secondaryParticleVector );
              fillResult( secondaryParticleVector, result);
              return result;
            }

          // Update evaporation channels and 
          // total emission probability.
          totalProbability = 0;
          for ( iChannel = channelVector.begin() ; iChannel != channelVector.end() ; *iChannel++ )  
            {
              ( *iChannel )->setNucleusA( nucleusA ); 
              ( *iChannel )->setNucleusZ( nucleusZ );
              ( *iChannel )->setExcitationEnergy( excE ); 
              ( *iChannel )->calculateProbability();
              totalProbability += ( *iChannel )->getProbability();
            }
        } // Treatment of physically acceptable particle ends.
    } // End of evaporation cycle.

  // Gamma de-excitation.
  G4BEGammaDeexcitation *pGammaChannel = new G4BEGammaDeexcitation;
  pGammaChannel->setNucleusA( nucleusA );
  pGammaChannel->setNucleusZ( nucleusZ );
  pGammaChannel->setVerboseLevel( verboseLevel );
  pGammaChannel->setExcitationEnergy( excE );

  // Emit equally sampled photons until all the excitation energy is
  // used; the last photon gets the remaining de-excitation energy.
  // Change of momentum of the nucleus is neglected.
  G4double gammaEnergy;
  G4double totalDeExcEnergy = 0;

  while ( excE > 0 )
    {
      pEmittedParticle = pGammaChannel->emit();
      gammaEnergy = pEmittedParticle->GetKineticEnergy();
      
      if ( ( totalDeExcEnergy + gammaEnergy ) > excE ) 
        {
          // All the remaining energy is used here.
          gammaEnergy = excE - totalDeExcEnergy;
          excE = 0;
        }

      totalDeExcEnergy += gammaEnergy; 

      if ( verboseLevel >= 10 )
        G4cout << " G4BertiniEvaporation : gamma de-excitation, g of " << gammaEnergy << " MeV " << G4endl;
      
      G4LorentzVector gammaFourVector( pEmittedParticle->GetMomentum(),
                                       pEmittedParticle->GetKineticEnergy() );
      gammaFourVector.boost( boostToLab );
      pEmittedParticle->SetKineticEnergy( gammaFourVector.e() );
      pEmittedParticle->SetMomentumDirection( gammaFourVector.vect().unit() );

      secondaryParticleVector.push_back( pEmittedParticle );

      } 

  delete pGammaChannel;

  // Residual nucleus is not returned.

  fillResult( secondaryParticleVector, result);
  
  return result;
}


void G4BertiniEvaporation::splitBe8( const G4double E,
                                     const G4ThreeVector boostToLab,
                                     std::vector< G4DynamicParticle * > & secondaryParticleVector )
{
  G4double kineticEnergy; 
  G4double u;
  G4double v;
  G4double w;
  const G4double Be8DecayEnergy = 0.093 * MeV; 

  if ( E <= 0 ) throw G4HadronicException(__FILE__, __LINE__,  "G4BertiniEvaporation : excitation energy < 0 " );
  if ( verboseLevel >= 4 ) G4cout << "     Be8 split to 2 x He4" << G4endl;

  kineticEnergy = 0.5 * ( E + Be8DecayEnergy ); 
  
  // Create two alpha particles in CMS frame.
  isotropicCosines( u , v , w );
  G4ThreeVector momentumDirectionCMS( u, v, w ); 

  G4DynamicParticle *pP1Cms = new G4DynamicParticle( G4Alpha::Alpha(),
                                                     momentumDirectionCMS,
                                                     kineticEnergy );
  G4DynamicParticle *pP2Cms = new G4DynamicParticle( G4Alpha::Alpha(),
                                                     -momentumDirectionCMS,
                                                     kineticEnergy );
  G4LorentzVector fourVector1( pP1Cms->GetMomentum(), 
                               pP1Cms->GetTotalEnergy() );
  G4LorentzVector fourVector2( pP2Cms->GetMomentum(), 
                               pP2Cms->GetTotalEnergy() );

  // Transform into lab frame by transforming the four vectors. Then
  // add to the vector of secondary particles.
  fourVector1.boost( boostToLab );
  fourVector2.boost( boostToLab );
  G4DynamicParticle * pP1Lab  = new G4DynamicParticle( G4Alpha::Alpha(),
                                                      fourVector1.vect(),
                                                      fourVector1.e() );
  G4DynamicParticle * pP2Lab  = new G4DynamicParticle( G4Alpha::Alpha(),
                                                      fourVector2.vect(),
                                                      fourVector2.e() );
  secondaryParticleVector.push_back( pP1Lab );
  secondaryParticleVector.push_back( pP2Lab );

  delete pP1Cms;
  delete pP2Cms;

  return;
}


void G4BertiniEvaporation::fillResult( std::vector<G4DynamicParticle *> secondaryParticleVector,
                                      G4FragmentVector * aResult )
{
  // Fill the vector pParticleChange with secondary particles stored in vector.
  for ( size_t i = 0 ; i < secondaryParticleVector.size() ; i++ )
  {
    G4int aZ = static_cast<G4int> (secondaryParticleVector[i]->GetDefinition()->GetPDGCharge() );
    G4int aA = static_cast<G4int> (secondaryParticleVector[i]->GetDefinition()->GetBaryonNumber());
    G4LorentzVector aMomentum = secondaryParticleVector[i]->Get4Momentum();
    if(aA>0) 
    {
      aResult->push_back( new G4Fragment(aA, aZ, aMomentum) ); 
    }
    else 
    {
      aResult->push_back( new G4Fragment(aMomentum, secondaryParticleVector[i]->GetDefinition()) ); 
    }
  }
  return;
}


void G4BertiniEvaporation::isotropicCosines( G4double & u, G4double & v, G4double & w )
{
  // Samples isotropic random direction cosines.
  G4double CosTheta = 1.0 - 2.0 * G4UniformRand();
  G4double SinTheta = std::sqrt( 1.0 - CosTheta * CosTheta );
  G4double Phi = twopi * G4UniformRand();

  u = std::cos( Phi ) * SinTheta;
  v = std::cos( Phi ) * CosTheta,
  w = std::sin( Phi );

  return;
}

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