G4LEAntiLambdaInelastic.cc

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//
// $Id$
//
// Hadronic Process: AntiLambda Inelastic Process
// J.L. Chuma, TRIUMF, 19-Feb-1997
// Modified by J.L.Chuma 30-Apr-97: added originalTarget for CalculateMomenta

#include "G4LEAntiLambdaInelastic.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "Randomize.hh"

void G4LEAntiLambdaInelastic::ModelDescription(std::ostream& outFile) const
{
  outFile << "G4LEAntiLambdaInelastic is one of the Low Energy Parameterized\n"
          << "(LEP) models used to implement inelastic anti-lambda\n"
          << "scattering from nuclei.  It is a re-engineered version of the\n"
          << "GHEISHA code of H. Fesefeldt.  It divides the initial\n"
          << "collision products into backward- and forward-going clusters\n"
          << "which are then decayed into final state hadrons.  The model\n"
          << "does not conserve energy on an event-by-event basis.  It may\n"
          << "be applied to anti-lambdas with initial energies between 0 and\n"
          << "25 GeV.\n";
}


G4HadFinalState*
G4LEAntiLambdaInelastic::ApplyYourself(const G4HadProjectile& aTrack,
                                       G4Nucleus& targetNucleus)
{
  const G4HadProjectile *originalIncident = &aTrack;

  // create the target particle
  G4DynamicParticle* originalTarget = targetNucleus.ReturnTargetParticle();
    
  if (verboseLevel > 1) {
    const G4Material *targetMaterial = aTrack.GetMaterial();
    G4cout << "G4LEAntiLambdaInelastic::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 ( (originalIncident->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 G4LEAntiLambdaInelastic::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 CASAL0 by H. Fesefeldt (13-Sep-1987)
  //
  // AntiLambda 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;
  const G4double pOriginal = originalIncident->GetTotalMomentum()/GeV;
  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 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;
    G4int counter = -1;
    for (npos = 0; npos < (numSec/3); ++npos) {
      for (nneg = std::max(0, npos-2); 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 = std::max(0,npos-1); 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];
    }

    // 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 = 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) {
            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 = 0; npos < numSec/3; ++npos) {
      nneg = npos;
      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 *aPiMinus = G4PionMinus::PionMinus();
  G4ParticleDefinition *aPiZero = G4PionZero::PionZero();
  G4ParticleDefinition *aKaonPlus = G4KaonPlus::KaonPlus();
  G4ParticleDefinition *aKaonMinus = G4KaonMinus::KaonMinus();
  G4ParticleDefinition *aKaonZL = G4KaonZeroLong::KaonZeroLong();
  G4ParticleDefinition *anAntiSigmaZero = G4AntiSigmaZero::AntiSigmaZero();
  G4ParticleDefinition *anAntiSigmaPlus = G4AntiSigmaPlus::AntiSigmaPlus();
  G4ParticleDefinition *anAntiSigmaMinus = G4AntiSigmaMinus::AntiSigmaMinus();
  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*10.0 );
  if (iplab >  9) iplab = G4int( (pOriginal- 1.0)*5.0  ) + 10;
  if (iplab > 14) iplab = G4int(  pOriginal- 2.0       ) + 15;
  if (iplab > 22) iplab = G4int( (pOriginal-10.0)/10.0 ) + 23;
  if (iplab > 24) iplab = 24;

  if (G4UniformRand() > anhl[iplab]) {
    if (availableEnergy <= aPiPlus->GetPDGMass()/MeV) {
      // not energetically possible to produce pion(s)
      quasiElastic = true;
      return;
    }    
    G4double n, anpn;
    GetNormalizationConstant (availableEnergy, n, anpn);
    G4double ran = G4UniformRand();
    G4double dum, excs = 0.0;
    if (targetParticle.GetDefinition() == aProton) {
      G4int counter = -1;
      for (npos = 0; npos < numSec/3 && ran>=excs; ++npos) {
        for (nneg = std::max(0,npos-2); 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--;
      G4int ncht = std::min(4, std::max(1, npos-nneg+2 ) );
      switch (ncht)
      {
        case 1:
          currentParticle.SetDefinitionAndUpdateE(anAntiSigmaMinus);
          incidentHasChanged = true;
          break;
        case 2:
          if (G4UniformRand() < 0.5) {
            if (G4UniformRand() < 0.5) {
              currentParticle.SetDefinitionAndUpdateE(anAntiSigmaZero);
              incidentHasChanged = true;
            } else {
              currentParticle.SetDefinitionAndUpdateE(anAntiSigmaMinus);
              incidentHasChanged = true;
              targetParticle.SetDefinitionAndUpdateE(aNeutron);
              targetHasChanged = true;
            }
          } else {
            if (G4UniformRand() >= 0.5) {
              currentParticle.SetDefinitionAndUpdateE(anAntiSigmaMinus);
              incidentHasChanged = true;
              targetParticle.SetDefinitionAndUpdateE(aNeutron);
              targetHasChanged = true;
            }
          }
          break;
        case 3:
          if (G4UniformRand() < 0.5) {
            if (G4UniformRand() < 0.5) {
              currentParticle.SetDefinitionAndUpdateE(anAntiSigmaZero);
              incidentHasChanged = true;
              targetParticle.SetDefinitionAndUpdateE(aNeutron);
              targetHasChanged = true;
            } else {
              currentParticle.SetDefinitionAndUpdateE(anAntiSigmaPlus);
              incidentHasChanged = true;
            }
          } else {
            if (G4UniformRand() < 0.5) {
              targetParticle.SetDefinitionAndUpdateE(aNeutron);
              targetHasChanged = true;
            } else {
              currentParticle.SetDefinitionAndUpdateE(anAntiSigmaPlus);
              incidentHasChanged = true;
            }
          }
          break;
        case 4:
          currentParticle.SetDefinitionAndUpdateE(anAntiSigmaPlus);
          incidentHasChanged = true;
          targetParticle.SetDefinitionAndUpdateE(aNeutron);
          targetHasChanged = true;
          break;
      } // end switch

    } else {
      // target must be a neutron
      G4int counter = -1;
      for (npos = 0; npos < numSec/3 && ran>=excs; ++npos) {
        for (nneg = std::max(0,npos-1); 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--;
      G4int ncht = std::min(4, std::max(1, npos-nneg+3) );
      switch (ncht)
      {
        case 1:
          currentParticle.SetDefinitionAndUpdateE(anAntiSigmaMinus);
          incidentHasChanged = true;
          targetParticle.SetDefinitionAndUpdateE(aProton);
          targetHasChanged = true;
          break;
        case 2:
          if (G4UniformRand() < 0.5) {
            if (G4UniformRand() < 0.5) {
              currentParticle.SetDefinitionAndUpdateE(anAntiSigmaZero);
              incidentHasChanged = true;
              targetParticle.SetDefinitionAndUpdateE(aProton);
              targetHasChanged = true;
            } else {
              currentParticle.SetDefinitionAndUpdateE(anAntiSigmaMinus);
              incidentHasChanged = true;
            }
          } else {
            if (G4UniformRand() < 0.5) {
              targetParticle.SetDefinitionAndUpdateE(aProton);
              targetHasChanged = true;
            } else {
              currentParticle.SetDefinitionAndUpdateE(anAntiSigmaMinus);
              incidentHasChanged = true;
            }
          }
          break;
        case 3:
          if (G4UniformRand() < 0.5) {
            if (G4UniformRand() < 0.5) {
              currentParticle.SetDefinitionAndUpdateE(anAntiSigmaZero);
              incidentHasChanged = true;
            } else {
              currentParticle.SetDefinitionAndUpdateE(anAntiSigmaPlus);
              incidentHasChanged = true;
              targetParticle.SetDefinitionAndUpdateE( aProton );
              targetHasChanged = true;
            }
          } else {
            if (G4UniformRand() >= 0.5) {
              currentParticle.SetDefinitionAndUpdateE(anAntiSigmaPlus);
              incidentHasChanged = true;
              targetParticle.SetDefinitionAndUpdateE(aProton);
              targetHasChanged = true;
            }
          }
          break;
        default:
          currentParticle.SetDefinitionAndUpdateE(anAntiSigmaPlus);
          incidentHasChanged = true;
          break;
      } // end of switch
    }
  } else { // random number <= anhl[iplab]
    if (centerofmassEnergy <= aPiPlus->GetPDGMass()/MeV+aKaonPlus->GetPDGMass()/MeV) {
      quasiElastic = true;
      return;
    }

    //  annihilation channels
    G4double n, anpn;
    GetNormalizationConstant(-centerofmassEnergy, n, anpn);
    G4double ran = G4UniformRand();
    G4double dum, excs = 0.0;
    if (targetParticle.GetDefinition() == aProton) {
      G4int 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*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;
              }
            }
          }
        }
      }
    } else {
      // target must be a neutron
      G4int counter = -1;
      for (npos = 0; npos < numSec/3 && ran >= excs; ++npos) {
        nneg = npos;
        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--;
    currentParticle.SetMass( 0.0 );
    targetParticle.SetMass( 0.0 );
  }

  SetUpPions(npos, nneg, nzero, vec, vecLen);
  if (currentParticle.GetMass() == 0.0) {
    if (nzero == 0) {
      if (nneg > 0) {
        for (G4int i = 0; i < vecLen; ++i) {
          if (vec[i]->GetDefinition() == aPiMinus) {
            vec[i]->SetDefinitionAndUpdateE( aKaonMinus );
            break;
          }
        }
      }
    } else {
      // nzero > 0
      if (nneg == 0) {
        for (G4int i = 0; i < vecLen; ++i) {
          if (vec[i]->GetDefinition() == aPiZero) {
            vec[i]->SetDefinitionAndUpdateE(aKaonZL);
            break;
          }
        }
      } else {
        //  nneg > 0
        if (G4UniformRand() < 0.5) {
          if (nneg > 0) {
            for (G4int i = 0; i < vecLen; ++i) {
              if (vec[i]->GetDefinition() == aPiMinus) {
                vec[i]->SetDefinitionAndUpdateE(aKaonMinus);
                break;
              }
            }
          }
        } else {
          // random number >= 0.5
          for (G4int i = 0; i < vecLen; ++i) {
            if (vec[i]->GetDefinition() == aPiZero) {
              vec[i]->SetDefinitionAndUpdateE( aKaonZL );
              break;
            }
          }
        }
      }
    }
  }
  return;
}

 /* end of file */