G4LEAntiOmegaMinusInelastic.cc

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// $Id$
//
// Hadronic Process: AntiOmegaMinus Inelastic Process
// J.L. Chuma, TRIUMF, 20-Feb-1997
// Modified by J.L.Chuma 30-Apr-97: added originalTarget for CalculateMomenta
//
// NOTE:  The FORTRAN version of the cascade, CASAOM, simply called the
//        routine for the OmegaMinus particle.  Hence, the Cascade function
//        below is just a copy of the Cascade from the OmegaMinus particle.
 
#include "G4LEAntiOmegaMinusInelastic.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "Randomize.hh"

void G4LEAntiOmegaMinusInelastic::ModelDescription(std::ostream& outFile) const
{
  outFile << "G4LEAntiOmegaMinusInelastic is one of the Low Energy\n"
          << "Parameterized (LEP) models used to implement inelastic\n"
          << "antiOmega- scattering from nuclei.  It is a re-engineered\n"
          << "version of the GHEISHA code of H. Fesefeldt.  It divides the\n"
          << "initial collision products into backward- and forward-going\n"
          << "clusters which are then decayed into final state hadrons.  The\n"
          << "model does not conserve energy on an event-by-event basis.  It\n"
          << "may be applied to antiOmega- with initial energies between 0\n"
          << "and 25 GeV.\n";
}

G4HadFinalState*
G4LEAntiOmegaMinusInelastic::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();

  if (verboseLevel > 1) {
    const G4Material *targetMaterial = aTrack.GetMaterial();
    G4cout << "kinetic energy = " << originalIncident->GetKineticEnergy()/MeV << "MeV, ";
    G4cout << "target material = " << targetMaterial->GetName() << ", ";
    G4cout << "target particle = " << originalTarget->GetDefinition()->GetParticleName()
           << G4endl;
  }

  // Fermi motion and evaporation
  // As of Geant3, the Fermi energy calculation had not been Done
  G4double ek = originalIncident->GetKineticEnergy()/MeV;
  G4double amas = originalIncident->GetDefinition()->GetPDGMass()/MeV;
  G4ReactionProduct modifiedOriginal;
  modifiedOriginal = *originalIncident;
    
  G4double tkin = targetNucleus.Cinema( ek );
  ek += tkin;
  modifiedOriginal.SetKineticEnergy( ek*MeV );
  G4double et = ek + amas;
  G4double p = std::sqrt( std::abs((et-amas)*(et+amas)) );
  G4double pp = modifiedOriginal.GetMomentum().mag()/MeV;
  if (pp > 0.0) {
    G4ThreeVector momentum = modifiedOriginal.GetMomentum();
    modifiedOriginal.SetMomentum( momentum * (p/pp) );
  }

  // calculate black track energies
  tkin = targetNucleus.EvaporationEffects( ek );
  ek -= tkin;
  modifiedOriginal.SetKineticEnergy( ek*MeV );
  et = ek + amas;
  p = std::sqrt( std::abs((et-amas)*(et+amas)) );
  pp = modifiedOriginal.GetMomentum().mag()/MeV;
  if (pp > 0.0) {
    G4ThreeVector momentum = modifiedOriginal.GetMomentum();
    modifiedOriginal.SetMomentum( momentum * (p/pp) );
  }
  G4ReactionProduct currentParticle = modifiedOriginal;
  G4ReactionProduct targetParticle;
  targetParticle = *originalTarget;
  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;
  const G4double anni = std::min( 1.3*currentParticle.GetTotalMomentum()/GeV, 0.4 );
    
  if ((currentParticle.GetKineticEnergy()/MeV > cutOff) || (G4UniformRand() > anni) )
    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);

  if (isotopeProduction) DoIsotopeCounting(originalIncident, targetNucleus);

  delete originalTarget;
  return &theParticleChange;
}
 
void G4LEAntiOmegaMinusInelastic::Cascade(
   G4FastVector<G4ReactionProduct,GHADLISTSIZE>& vec,
   G4int& vecLen,
   const G4HadProjectile* originalIncident,
   G4ReactionProduct& currentParticle,
   G4ReactionProduct& targetParticle,
   G4bool& incidentHasChanged,
   G4bool& targetHasChanged,
   G4bool& quasiElastic)
{
  // derived from original FORTRAN code CASOM by H. Fesefeldt (31-Jan-1989)
  //
  // AntiOmegaMinus 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()/MeV;
  const G4double etOriginal = originalIncident->GetTotalEnergy()/MeV;
  const G4double targetMass = targetParticle.GetMass()/MeV;
  G4double centerofmassEnergy = std::sqrt(mOriginal*mOriginal +
                                          targetMass*targetMass +
                                          2.0*targetMass*etOriginal);
  G4double availableEnergy = centerofmassEnergy-(targetMass+mOriginal);
  if (availableEnergy <= G4PionPlus::PionPlus()->GetPDGMass()/MeV) {
    // not energetically possible to produce pion(s)
    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

  // npos = number of pi+, nneg = number of pi-, nzero = number of pi0
  G4int counter, nt=0;
  G4int npos = 0, nneg = 0, nzero = 0;
  G4double test;
  const G4double c = 1.25;    
  const G4double b[] = { 0.7, 0.7 };
  if (first) {  // Computation of normalization constants 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 (npos = 0; npos < (numSec/3); ++npos) {
      for (nneg = std::max(0,npos-1); nneg <= (npos+1); ++nneg) {
        for (nzero = 0; nzero < numSec/3; ++nzero) {
          if (++counter < numMul) {
            nt = npos+nneg+nzero;
            if (nt > 0 && nt <= numSec) {
              protmul[counter] = Pmltpc(npos,nneg,nzero,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 (npos = 0; npos < numSec/3; ++npos) {
      for (nneg = npos; nneg <= (npos+2); ++nneg) {
        for (nzero = 0; nzero < numSec/3; ++nzero) {
          if (++counter < numMul) {
            nt = npos+nneg+nzero;
            if ( nt>0 && nt<=numSec ) {
              neutmul[counter] = Pmltpc(npos,nneg,nzero,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 *aSigmaPlus = G4SigmaPlus::SigmaPlus();
  G4ParticleDefinition *aXiZero = G4XiZero::XiZero();
  G4double n, anpn;
  GetNormalizationConstant( availableEnergy, n, anpn );
  G4double ran = G4UniformRand();
  G4double dum, excs = 0.0;
  G4int nvefix = 0;
  if (targetParticle.GetDefinition() == aProton) {
    counter = -1;
    for (npos = 0; npos < numSec/3 && ran>=excs; ++npos) {
      for (nneg = std::max(0,npos-1); nneg <= (npos+1) && ran>=excs; ++nneg) {
        for (nzero = 0; nzero < numSec/3 && ran>=excs; ++nzero) {
          if ( ++counter < numMul ) {
            nt = npos+nneg+nzero;
            if (nt > 0 && nt <= numSec) {
              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;
    }
    npos--; nneg--; nzero--;

    // 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

    if (npos < nneg) {
      if (npos+1 == nneg) {
        currentParticle.SetDefinitionAndUpdateE(aXiZero);
        incidentHasChanged = true;
        nvefix = 1;
      } else {
        // charge mismatch
        currentParticle.SetDefinitionAndUpdateE(aSigmaPlus);
        incidentHasChanged = true;
        nvefix = 2;
      }
    } else if (npos > nneg) {
      targetParticle.SetDefinitionAndUpdateE(aNeutron);
      targetHasChanged = true;
    }
  } else {
    // target must be a neutron
    counter = -1;
    for (npos = 0; npos < numSec/3 && ran >= excs; ++npos) {
      for (nneg = npos; nneg <= (npos+2) && ran>=excs; ++nneg) {
        for (nzero = 0; nzero < numSec/3 && ran>=excs; ++nzero) {
          if (++counter < numMul) {
            nt = npos+nneg+nzero;
            if (nt > 0 && 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;
    }
    npos--; nneg--; nzero--;
    if (npos+1 < nneg) {
      if( npos+2 == nneg) {
        currentParticle.SetDefinitionAndUpdateE( aXiZero );
        incidentHasChanged = true;
        nvefix = 1;
      } else {
        // charge mismatch
        currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
        incidentHasChanged = true;
        nvefix = 2;
      }
      targetParticle.SetDefinitionAndUpdateE( aProton );
      targetHasChanged = true;
    } else if (npos+1 == nneg) {
      targetParticle.SetDefinitionAndUpdateE( aProton );
      targetHasChanged = true;
    }
  }

  SetUpPions(npos, nneg, nzero, vec, vecLen);
  for (G4int i = 0; i < vecLen && nvefix > 0; ++i) {
    if (vec[i]->GetDefinition() == G4PionMinus::PionMinus() ) {

      // correct the strangeness by replacing a pi- by a kaon-
      if (nvefix >= 1) vec[i]->SetDefinitionAndUpdateE(aKaonMinus);
        --nvefix;
    }
  }
  return;
}

 /* end of file */