G4RPGOmegaMinusInelastic.cc

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// $Id$
//
 
#include "G4RPGOmegaMinusInelastic.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "Randomize.hh"

G4HadFinalState*
G4RPGOmegaMinusInelastic::ApplyYourself( const G4HadProjectile &aTrack,
                                         G4Nucleus &targetNucleus )
{
  const G4HadProjectile *originalIncident = &aTrack;
  if (originalIncident->GetKineticEnergy()<= 0.1*MeV) 
  {
    theParticleChange.SetStatusChange(isAlive);
    theParticleChange.SetEnergyChange(aTrack.GetKineticEnergy());
    theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit()); 
    return &theParticleChange;      
  }
    
  // create the target particle
    
  G4DynamicParticle *originalTarget = targetNucleus.ReturnTargetParticle();
//    G4double targetMass = originalTarget->GetDefinition()->GetPDGMass();
  G4ReactionProduct targetParticle( originalTarget->GetDefinition() );
    
  if( verboseLevel > 1 )
  {
    const G4Material *targetMaterial = aTrack.GetMaterial();
    G4cout << "G4RPGOmegaMinusInelastic::ApplyYourself called" << G4endl;
    G4cout << "kinetic energy = " << originalIncident->GetKineticEnergy() << "MeV, ";
    G4cout << "target material = " << targetMaterial->GetName() << ", ";
    G4cout << "target particle = " << originalTarget->GetDefinition()->GetParticleName()
           << G4endl;
  }
    G4ReactionProduct currentParticle( const_cast<G4ParticleDefinition *>(originalIncident->GetDefinition() ));
    currentParticle.SetMomentum( originalIncident->Get4Momentum().vect() );
    currentParticle.SetKineticEnergy( originalIncident->GetKineticEnergy() );
    
    // Fermi motion and evaporation
    // As of Geant3, the Fermi energy calculation had not been Done
    
    G4double ek = originalIncident->GetKineticEnergy();
    G4double amas = originalIncident->GetDefinition()->GetPDGMass();
    
    G4double tkin = targetNucleus.Cinema( ek );
    ek += tkin;
    currentParticle.SetKineticEnergy( ek );
    G4double et = ek + amas;
    G4double p = std::sqrt( std::abs((et-amas)*(et+amas)) );
    G4double pp = currentParticle.GetMomentum().mag();
    if( pp > 0.0 )
    {
      G4ThreeVector momentum = currentParticle.GetMomentum();
      currentParticle.SetMomentum( momentum * (p/pp) );
    }
    
    // calculate black track energies
    
    tkin = targetNucleus.EvaporationEffects( ek );
    ek -= tkin;
    currentParticle.SetKineticEnergy( ek );
    et = ek + amas;
    p = std::sqrt( std::abs((et-amas)*(et+amas)) );
    pp = currentParticle.GetMomentum().mag();
    if( pp > 0.0 )
    {
      G4ThreeVector momentum = currentParticle.GetMomentum();
      currentParticle.SetMomentum( momentum * (p/pp) );
    }

    G4ReactionProduct modifiedOriginal = currentParticle;

    currentParticle.SetSide( 1 ); // incident always goes in forward hemisphere
    targetParticle.SetSide( -1 );  // target always goes in backward hemisphere
    G4bool incidentHasChanged = false;
    G4bool targetHasChanged = false;
    G4bool quasiElastic = false;
    G4FastVector<G4ReactionProduct,GHADLISTSIZE> vec;  // vec will contain the secondary particles
    G4int vecLen = 0;
    vec.Initialize( 0 );

    const G4double cutOff = 0.1*MeV;
    if( currentParticle.GetKineticEnergy() > cutOff )
      Cascade( vec, vecLen,
               originalIncident, currentParticle, targetParticle,
               incidentHasChanged, targetHasChanged, quasiElastic );
    
    CalculateMomenta( vec, vecLen,
                      originalIncident, originalTarget, modifiedOriginal,
                      targetNucleus, currentParticle, targetParticle,
                      incidentHasChanged, targetHasChanged, quasiElastic );
    
    SetUpChange( vec, vecLen,
                 currentParticle, targetParticle,
                 incidentHasChanged );
    
  delete originalTarget;
  return &theParticleChange;
}

 
void G4RPGOmegaMinusInelastic::Cascade(
   G4FastVector<G4ReactionProduct,GHADLISTSIZE> &vec,
   G4int& vecLen,
   const G4HadProjectile *originalIncident,
   G4ReactionProduct &currentParticle,
   G4ReactionProduct &targetParticle,
   G4bool &incidentHasChanged,
   G4bool &targetHasChanged,
   G4bool &quasiElastic )
{
  // Derived from H. Fesefeldt's original FORTRAN code CASOM
  // OmegaMinus undergoes interaction with nucleon within a nucleus.  Check if it is
  // energetically possible to produce pions/kaons.  In not, assume nuclear excitation
  // occurs and input particle is degraded in energy. No other particles are produced.
  // If reaction is possible, find the correct number of pions/protons/neutrons
  // produced using an interpolation to multiplicity data.  Replace some pions or
  // protons/neutrons by kaons or strange baryons according to the average
  // multiplicity per Inelastic reaction.

  const G4double mOriginal = originalIncident->GetDefinition()->GetPDGMass();
  const G4double etOriginal = originalIncident->GetTotalEnergy();
//    const G4double pOriginal = originalIncident->GetTotalMomentum();
  const G4double targetMass = targetParticle.GetMass();
  G4double centerofmassEnergy = std::sqrt( mOriginal*mOriginal +
                                      targetMass*targetMass +
                                      2.0*targetMass*etOriginal );
  G4double availableEnergy = centerofmassEnergy-(targetMass+mOriginal);
  if( availableEnergy <= G4PionPlus::PionPlus()->GetPDGMass() )
  {
    quasiElastic = true;
    return;
  }
    static G4bool first = true;
    const G4int numMul = 1200;
    const G4int numSec = 60;
    static G4double protmul[numMul], protnorm[numSec]; // proton constants
    static G4double neutmul[numMul], neutnorm[numSec]; // neutron constants
    // np = number of pi+, nneg = number of pi-, nz = number of pi0
    G4int counter, nt=0, np=0, nneg=0, nz=0;
    G4double test;
    const G4double c = 1.25;    
    const G4double b[] = { 0.70, 0.70 };
    if( first )    // compute normalization constants, this will only be Done once
    {
      first = false;
      G4int i;
      for( i=0; i<numMul; ++i )protmul[i] = 0.0;
      for( i=0; i<numSec; ++i )protnorm[i] = 0.0;
      counter = -1;
      for( np=0; np<(numSec/3); ++np )
      {
        for( nneg=std::max(0,np-1); nneg<=(np+1); ++nneg )
        {
          for( nz=0; nz<numSec/3; ++nz )
          {
            if( ++counter < numMul )
            {
              nt = np+nneg+nz;
              if( nt > 0 )
              {
                protmul[counter] = Pmltpc(np,nneg,nz,nt,b[0],c);
                protnorm[nt-1] += protmul[counter];
              }
            }
          }
        }
      }
      for( i=0; i<numMul; ++i )neutmul[i] = 0.0;
      for( i=0; i<numSec; ++i )neutnorm[i] = 0.0;
      counter = -1;
      for( np=0; np<numSec/3; ++np )
      {
        for( nneg=np; nneg<=(np+2); ++nneg )
        {
          for( nz=0; nz<numSec/3; ++nz )
          {
            if( ++counter < numMul )
            {
              nt = np+nneg+nz;
              if( (nt>0) && (nt<=numSec) )
              {
                neutmul[counter] = Pmltpc(np,nneg,nz,nt,b[1],c);
                neutnorm[nt-1] += neutmul[counter];
              }
            }
          }
        }
      }
      for( i=0; i<numSec; ++i )
      {
        if( protnorm[i] > 0.0 )protnorm[i] = 1.0/protnorm[i];
        if( neutnorm[i] > 0.0 )neutnorm[i] = 1.0/neutnorm[i];
      }
    }   // end of initialization
    
    const G4double expxu = 82.;           // upper bound for arg. of exp
    const G4double expxl = -expxu;        // lower bound for arg. of exp
    G4ParticleDefinition *aNeutron = G4Neutron::Neutron();
    G4ParticleDefinition *aProton = G4Proton::Proton();
    G4ParticleDefinition *aKaonMinus = G4KaonMinus::KaonMinus();
    G4ParticleDefinition *aPiMinus = G4PionMinus::PionMinus();
    G4ParticleDefinition *aSigmaPlus = G4SigmaPlus::SigmaPlus();
    G4ParticleDefinition *aXiZero = G4XiZero::XiZero();
    
    // energetically possible to produce pion(s)  -->  inelastic scattering
    
    G4double n, anpn;
    GetNormalizationConstant( availableEnergy, n, anpn );
    G4double ran = G4UniformRand();
    G4double dum, excs = 0.0;
    if( targetParticle.GetDefinition() == aProton )
    {
      counter = -1;
      for( np=0; np<numSec/3 && ran>=excs; ++np )
      {
        for( nneg=std::max(0,np-1); nneg<=(np+1) && ran>=excs; ++nneg )
        {
          for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
          {
            if( ++counter < numMul )
            {
              nt = np+nneg+nz;
              if( nt > 0 )
              {
                test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
                dum = (pi/anpn)*nt*protmul[counter]*protnorm[nt-1]/(2.0*n*n);
                if( std::fabs(dum) < 1.0 )
                {
                  if( test >= 1.0e-10 )excs += dum*test;
                }
                else
                  excs += dum*test;
              }
            }
          }
        }
      }
      if( ran >= excs )  // 3 previous loops continued to the end
      {
        quasiElastic = true;
        return;
      }
      np--; nneg--; nz--;
    }
    else  // target must be a neutron
    {
      counter = -1;
      for( np=0; np<numSec/3 && ran>=excs; ++np )
      {
        for( nneg=np; nneg<=(np+2) && ran>=excs; ++nneg )
        {
          for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
          {
            if( ++counter < numMul )
            {
              nt = np+nneg+nz;
              if( (nt>=1) && (nt<=numSec) )
              {
                test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
                dum = (pi/anpn)*nt*neutmul[counter]*neutnorm[nt-1]/(2.0*n*n);
                if( std::fabs(dum) < 1.0 )
                {
                  if( test >= 1.0e-10 )excs += dum*test;
                }
                else
                  excs += dum*test;
              }
            }
          }
        }
      }
      if( ran >= excs )  // 3 previous loops continued to the end
      {
        quasiElastic = true;
        return;
      }
      np--; nneg--; nz--;
    }
    // number of secondary mesons determined by kno distribution
    // check for total charge of final state mesons to determine
    // the kind of baryons to be produced, taking into account
    // charge and strangeness conservation
    //
    G4int nvefix = 0;
    if( targetParticle.GetDefinition() == aProton )
    {
      if( nneg > np )
      {
        if( nneg == np+1 )
        {
          currentParticle.SetDefinitionAndUpdateE( aXiZero );
          nvefix = 1;
        }
        else
        {
          currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
          nvefix = 2;
        }
        incidentHasChanged = true;
      }
      else if( nneg < np )
      {
        targetParticle.SetDefinitionAndUpdateE( aNeutron );
        targetHasChanged = true;
      }
    }
    else // target is a neutron
    {
      if( np+1 < nneg )
      {
        if( nneg == np+2 )
        {
          currentParticle.SetDefinitionAndUpdateE( aXiZero );
          incidentHasChanged = true;
          nvefix = 1;
        }
        else   // charge mismatch
        {
          currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
          incidentHasChanged = true;
          nvefix = 2;
        }
        targetParticle.SetDefinitionAndUpdateE( aProton );
        targetHasChanged = true;
      }
      else if( nneg == np+1 )
      {
        targetParticle.SetDefinitionAndUpdateE( aProton );
        targetHasChanged = true;
      }
    }

  SetUpPions(np, nneg, nz, vec, vecLen);
  for (G4int i = 0; i < vecLen && nvefix > 0; ++i) {
    if (vec[i]->GetDefinition() == aPiMinus) {
      if( nvefix >= 1 )vec[i]->SetDefinitionAndUpdateE(aKaonMinus);
      --nvefix;
    }
  }

  return;
}

 /* end of file */