G4LEAntiSigmaMinusInelastic.cc

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// $Id$
//
// Hadronic Process: AntiSigmaMinus Inelastic Process
// J.L. Chuma, TRIUMF, 19-Feb-1997
// J.P. Wellisch: 25.Apr-97: counter errors removed lines 426, 447
// Modified by J.L.Chuma 30-Apr-97: added originalTarget for CalculateMomenta
 
#include "G4LEAntiSigmaMinusInelastic.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "Randomize.hh"

void G4LEAntiSigmaMinusInelastic::ModelDescription(std::ostream& outFile) const
{
  outFile << "G4LEAntiSigmaMinusInelastic is one of the Low Energy\n"
          << "Parameterized (LEP) models used to implement inelastic\n"
          << "antiSigma- 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 antiSigma- with initial energies between 0\n"
          << "and 25 GeV.\n";
}


G4HadFinalState*
G4LEAntiSigmaMinusInelastic::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 << "G4LEAntiSigmaMinusInelastic::ApplyYourself called" << G4endl;
    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 G4LEAntiSigmaMinusInelastic::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 CASASM by H. Fesefeldt (13-Sep-1987)
  //
  // AntiSigmaMinus 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 pOriginal = originalIncident->GetTotalMomentum()/MeV;
  const G4double targetMass = targetParticle.GetMass()/MeV;
  G4double centerofmassEnergy = std::sqrt(mOriginal*mOriginal +
                                          targetMass*targetMass +
                                          2.0*targetMass*etOriginal);
  G4double availableEnergy = centerofmassEnergy-(targetMass+mOriginal);
    
  static G4bool first = true;
  const G4int numMul = 1200;
  const G4int numMulA = 400;
  const G4int numSec = 60;
  static G4double protmul[numMul], protnorm[numSec]; // proton constants
  static G4double neutmul[numMul], neutnorm[numSec]; // neutron constants
  static G4double protmulA[numMulA], protnormA[numSec]; // proton constants
  static G4double neutmulA[numMulA], neutnormA[numSec]; // neutron constants

  // npos = number of pi+, nneg = number of pi-, nzero = number of pi0
  G4int counter, nt=0, npos=0, nneg=0, nzero=0;
  G4double test;
  const G4double c = 1.25;    
  const G4double b[2] = { 0.7, 0.7 };
    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( npos=0; npos<(numSec/3); ++npos )
      {
        for( nneg=std::max(0,npos-2); nneg<=npos; ++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=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 )
              {
                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];
      }
      //
      // do the same for annihilation channels
      //
      for( i=0; i<numMulA; ++i )protmulA[i] = 0.0;
      for( i=0; i<numSec; ++i )protnormA[i] = 0.0;
      counter = -1;
      for( npos=2; npos<(numSec/3); ++npos )
      {
        nneg = npos-2;
        for( nzero=0; nzero<numSec/3; ++nzero )
        {
          if( ++counter < numMulA )
          {
            nt = npos+nneg+nzero;
            if( nt>1 && nt<=numSec )
            {
              protmulA[counter] = Pmltpc(npos,nneg,nzero,nt,b[0],c);
              protnormA[nt-1] += protmulA[counter];
            }
          }
        }
      }
      for( i=0; i<numMulA; ++i )neutmulA[i] = 0.0;
      for( i=0; i<numSec; ++i )neutnormA[i] = 0.0;
      counter = -1;
       for( npos=1; npos<numSec/3; ++npos )
       {
        nneg = npos-1;
        for( nzero=0; nzero<numSec/3; ++nzero )
        {
          if( ++counter < numMulA )
          {
            nt = npos+nneg+nzero;
            if( nt>1 && nt<=numSec )
            {
              neutmulA[counter] = Pmltpc(npos,nneg,nzero,nt,b[1],c);
              neutnormA[nt-1] += neutmulA[counter];
            }
          }
        }
      }
      for( i=0; i<numSec; ++i )
      {
        if( protnormA[i] > 0.0 )protnormA[i] = 1.0/protnormA[i];
        if( neutnormA[i] > 0.0 )neutnormA[i] = 1.0/neutnormA[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 *aPiPlus = G4PionPlus::PionPlus();
    G4ParticleDefinition *aKaonMinus = G4KaonMinus::KaonMinus();
    G4ParticleDefinition *aKaonZL = G4KaonZeroLong::KaonZeroLong();
    G4ParticleDefinition *aKaonPlus = G4KaonPlus::KaonPlus();
    G4ParticleDefinition *anAntiLambda = G4AntiLambda::AntiLambda();
    G4ParticleDefinition *anAntiSigmaZero = G4AntiSigmaZero::AntiSigmaZero();
    const G4double anhl[] = {1.00,1.00,1.00,1.00,1.00,1.00,1.00,1.00,0.97,0.88,
                             0.85,0.81,0.75,0.64,0.64,0.55,0.55,0.45,0.47,0.40,
                             0.39,0.36,0.33,0.10,0.01};
    G4int iplab = G4int( pOriginal/GeV*10.0 );
    if( iplab >  9 )iplab = G4int( (pOriginal/GeV- 1.0)*5.0  ) + 10;
    if( iplab > 14 )iplab = G4int(  pOriginal/GeV- 2.0       ) + 15;
    if( iplab > 23 )iplab = G4int( (pOriginal/GeV-10.0)/10.0 ) + 23;
    if( iplab > 24 )iplab = 24;
    if( G4UniformRand() > anhl[iplab] )
    {
      if( availableEnergy <= aPiPlus->GetPDGMass()/MeV )
      {
        quasiElastic = true;
        return;
      }
      G4double n, anpn;
      GetNormalizationConstant( availableEnergy, n, anpn );
      G4double ran = G4UniformRand();
      G4double dum, excs = 0.0;
      if( targetParticle.GetDefinition() == aProton )
      {
        counter = -1;
        for( npos=0; npos<numSec/3 && ran>=excs; ++npos )
        {
          for( nneg=std::max(0,npos-2); nneg<=npos && 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--;
        G4int ncht = std::min( 3, std::max( 1, npos-nneg+1 ) );
        switch( ncht )
        {
         case 1:
           break;
         case 2:
           if( G4UniformRand() < 0.5 )
           {
             targetParticle.SetDefinitionAndUpdateE( aNeutron );
             targetHasChanged = true;
           }
           else
           {
             if( G4UniformRand() < 0.5 )
               currentParticle.SetDefinitionAndUpdateE( anAntiLambda );
             else
               currentParticle.SetDefinitionAndUpdateE( anAntiSigmaZero );
             incidentHasChanged = true;
           }             
           break;
         case 3:
           if( G4UniformRand() < 0.5 )
             currentParticle.SetDefinitionAndUpdateE( anAntiLambda );
           else
             currentParticle.SetDefinitionAndUpdateE( anAntiSigmaZero );
           incidentHasChanged = true;
           targetParticle.SetDefinitionAndUpdateE( aNeutron );
           targetHasChanged = true;
           break;
        }
      }
      else  // target must be a neutron
      {
        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*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--;
        G4int ncht = std::min( 3, std::max( 1, npos-nneg+2 ) );
        switch( ncht )
        {
         case 1:
           {
             targetParticle.SetDefinitionAndUpdateE( aProton );
             targetHasChanged = true;
           }
           break;
         case 2:
           if( G4UniformRand() < 0.5 )
           {
             if( G4UniformRand() < 0.5 )
             {
               currentParticle.SetDefinitionAndUpdateE( anAntiLambda );
               incidentHasChanged = true;
               targetParticle.SetDefinitionAndUpdateE( aProton );
               targetHasChanged = true;
             }
           }
           else
           {
             if( G4UniformRand() < 0.5 )
             {
               currentParticle.SetDefinitionAndUpdateE( anAntiSigmaZero );
               incidentHasChanged = true;
               targetParticle.SetDefinitionAndUpdateE( aProton );
               targetHasChanged = true;
             }
           }
           break;
         case 3:
           if( G4UniformRand() < 0.5 )
             currentParticle.SetDefinitionAndUpdateE( anAntiLambda );
           else
             currentParticle.SetDefinitionAndUpdateE( anAntiSigmaZero );
           incidentHasChanged = true;
           break;
        }
      }
    }
    else  // random number <= anhl[iplab]
    {
      if( centerofmassEnergy <= aPiPlus->GetPDGMass()/MeV+aKaonPlus->GetPDGMass()/MeV )
      {
        quasiElastic = true;
        return;
      }
      G4double n, anpn;
      GetNormalizationConstant( -centerofmassEnergy, n, anpn );
      G4double ran = G4UniformRand();
      G4double dum, excs = 0.0;
      if( targetParticle.GetDefinition() == aProton )
      {
        counter = -1;
        for( npos=2; npos<numSec/3 && ran>=excs; ++npos )
        {
          nneg=npos-2;
          for( nzero=0; nzero<numSec/3 && ran>=excs; ++nzero )
          {
            if( ++counter < numMulA )
            {
              nt = npos+nneg+nzero;
              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*protmulA[counter]*protnormA[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--; nzero--;
      }
      else  // target must be a neutron
      {
        counter = -1;
        for( npos=1; npos<numSec/3 && ran>=excs; ++npos )
        {
          nneg = npos-1;
          for( nzero=0; nzero<numSec/3 && ran>=excs; ++nzero )
          {
            if( ++counter < numMulA )
            {
              nt = npos+nneg+nzero;
              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*neutmulA[counter]*neutnormA[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--; nzero--;
      }
      if( nzero > 0 )
      {
        if( nneg > 0 )
        {
          if( G4UniformRand() < 0.5 )
          {
            vec.Initialize( 1 );
            G4ReactionProduct *p = new G4ReactionProduct;
            p->SetDefinition( aKaonMinus );
            (G4UniformRand() < 0.5) ? p->SetSide( -1 ) : p->SetSide( 1 );
            vec.SetElement( vecLen++, p );
            --nneg;
          }
          else   // random number >= 0.5
          {
            vec.Initialize( 1 );
            G4ReactionProduct *p = new G4ReactionProduct;
            p->SetDefinition( aKaonZL );
            (G4UniformRand() < 0.5) ? p->SetSide( -1 ) : p->SetSide( 1 );
            vec.SetElement( vecLen++, p );
            --nzero;
          }
        }
        else   // nneg == 0
        {
          vec.Initialize( 1 );
          G4ReactionProduct *p = new G4ReactionProduct;
          p->SetDefinition( aKaonZL );
          (G4UniformRand() < 0.5) ? p->SetSide( -1 ) : p->SetSide( 1 );
          vec.SetElement( vecLen++, p );
          --nzero;
        }
      }
      else    //  nzero == 0
      {
        if( nneg > 0 )
        {
          vec.Initialize( 1 );
          G4ReactionProduct *p = new G4ReactionProduct;
          p->SetDefinition( aKaonMinus );
          (G4UniformRand() < 0.5) ? p->SetSide( -1 ) : p->SetSide( 1 );
          vec.SetElement( vecLen++, p );
          --nneg;
        }
      }
      currentParticle.SetMass( 0.0 );
      targetParticle.SetMass( 0.0 );
    }
    SetUpPions( npos, nneg, nzero, vec, vecLen );
    return;
}

 /* end of file */