G4HEAntiSigmaPlusInelastic.cc

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// $Id$
//

// G4 Process: Gheisha High Energy Collision model.
// This includes the high energy cascading model, the two-body-resonance model
// and the low energy two-body model. Not included are the low energy stuff
// like nuclear reactions, nuclear fission without any cascading and all
// processes for particles at rest.  
// First work done by J.L.Chuma and F.W.Jones, TRIUMF, June 96.  
// H. Fesefeldt, RWTH-Aachen, 23-October-1996
 
#include "G4HEAntiSigmaPlusInelastic.hh"
#include "globals.hh"
#include "G4ios.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"

void G4HEAntiSigmaPlusInelastic::ModelDescription(std::ostream& outFile) const
{
  outFile << "G4HEAntiSigmaPlusInelastic is one of the High Energy\n"
          << "Parameterized (HEP) models used to implement inelastic\n"
          << "anti-Sigma+ 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.\n"
          << "The model does not conserve energy on an event-by-event\n"
          << "basis.  It may be applied to anti-Sigma+ with initial\n"
          << "energies above 20 GeV.\n";
}


G4HadFinalState*
G4HEAntiSigmaPlusInelastic::ApplyYourself(const G4HadProjectile& aTrack,
                                          G4Nucleus& targetNucleus)
{
  G4HEVector* pv = new G4HEVector[MAXPART];
  const G4HadProjectile* aParticle = &aTrack;
  const G4double atomicWeight = targetNucleus.GetA_asInt();
  const G4double atomicNumber = targetNucleus.GetZ_asInt();
  G4HEVector incidentParticle(aParticle);

  G4int incidentCode = incidentParticle.getCode();
  G4double incidentMass = incidentParticle.getMass();
  G4double incidentTotalEnergy = incidentParticle.getEnergy();

  // G4double incidentTotalMomentum = incidentParticle.getTotalMomentum();
  // DHW 19 May 2011: variable set but not used

  G4double incidentKineticEnergy = incidentTotalEnergy - incidentMass;

  if (incidentKineticEnergy < 1.)
    G4cout << "GHEAntiSigmaPlusInelastic: incident energy < 1 GeV" << G4endl;

  if (verboseLevel > 1) {
    G4cout << "G4HEAntiSigmaPlusInelastic::ApplyYourself" << G4endl;
    G4cout << "incident particle " << incidentParticle.getName()
           << "mass "              << incidentMass
           << "kinetic energy "    << incidentKineticEnergy
           << G4endl;
    G4cout << "target material with (A,Z) = (" 
           << atomicWeight << "," << atomicNumber << ")" << G4endl;
  }

  G4double inelasticity = NuclearInelasticity(incidentKineticEnergy, 
                                              atomicWeight, atomicNumber);
  if (verboseLevel > 1)
    G4cout << "nuclear inelasticity = " << inelasticity << G4endl;

  incidentKineticEnergy -= inelasticity;
    
  G4double excitationEnergyGNP = 0.;
  G4double excitationEnergyDTA = 0.; 

  G4double excitation = NuclearExcitation(incidentKineticEnergy,
                                          atomicWeight, atomicNumber,
                                          excitationEnergyGNP,
                                          excitationEnergyDTA);
  if (verboseLevel > 1)
    G4cout << "nuclear excitation = " << excitation << excitationEnergyGNP 
           << excitationEnergyDTA << G4endl;             

  incidentKineticEnergy -= excitation;
  incidentTotalEnergy = incidentKineticEnergy + incidentMass;
  // incidentTotalMomentum = std::sqrt( (incidentTotalEnergy-incidentMass)                    
  //                                   *(incidentTotalEnergy+incidentMass));
  // DHW 19 May 2011: variable set but not used

  G4HEVector targetParticle;
  if (G4UniformRand() < atomicNumber/atomicWeight) { 
    targetParticle.setDefinition("Proton");
  } else { 
    targetParticle.setDefinition("Neutron");
  }

  G4double targetMass = targetParticle.getMass();
  G4double centerOfMassEnergy = std::sqrt(incidentMass*incidentMass
                                        + targetMass*targetMass
                                        + 2.0*targetMass*incidentTotalEnergy);
  G4double availableEnergy = centerOfMassEnergy - targetMass - incidentMass;

  G4bool inElastic = true;
  vecLength = 0; 
        
  if (verboseLevel > 1)
    G4cout << "ApplyYourself: CallFirstIntInCascade for particle "
           << incidentCode << G4endl;

  G4bool successful = false; 
    
  FirstIntInCasAntiSigmaPlus(inElastic, availableEnergy, pv, vecLength,
                             incidentParticle, targetParticle, atomicWeight);

  if (verboseLevel > 1)
    G4cout << "ApplyYourself::StrangeParticlePairProduction" << G4endl;

  if ((vecLength > 0) && (availableEnergy > 1.)) 
    StrangeParticlePairProduction(availableEnergy, centerOfMassEnergy,
                                  pv, vecLength,
                                  incidentParticle, targetParticle);

  HighEnergyCascading(successful, pv, vecLength,
                      excitationEnergyGNP, excitationEnergyDTA,
                      incidentParticle, targetParticle,
                      atomicWeight, atomicNumber);
  if (!successful)
    HighEnergyClusterProduction(successful, pv, vecLength,
                                excitationEnergyGNP, excitationEnergyDTA,
                                incidentParticle, targetParticle,
                                atomicWeight, atomicNumber);
  if (!successful) 
    MediumEnergyCascading(successful, pv, vecLength, 
                          excitationEnergyGNP, excitationEnergyDTA, 
                          incidentParticle, targetParticle,
                          atomicWeight, atomicNumber);

  if (!successful)
    MediumEnergyClusterProduction(successful, pv, vecLength,
                                  excitationEnergyGNP, excitationEnergyDTA,       
                                  incidentParticle, targetParticle,
                                  atomicWeight, atomicNumber);
  if (!successful)
    QuasiElasticScattering(successful, pv, vecLength,
                           excitationEnergyGNP, excitationEnergyDTA,
                           incidentParticle, targetParticle, 
                           atomicWeight, atomicNumber);
  if (!successful)
    ElasticScattering(successful, pv, vecLength,
                      incidentParticle,    
                      atomicWeight, atomicNumber);

  if (!successful)
    G4cout << "GHEInelasticInteraction::ApplyYourself fails to produce final state particles"
           << G4endl;

  FillParticleChange(pv,  vecLength);
  delete [] pv;
  theParticleChange.SetStatusChange(stopAndKill);
  return &theParticleChange;
}


void
G4HEAntiSigmaPlusInelastic::FirstIntInCasAntiSigmaPlus(G4bool& inElastic,
                                                       const G4double availableEnergy,
                                                       G4HEVector pv[],
                                                       G4int& vecLen,
                                                       const G4HEVector& incidentParticle,
                                                       const G4HEVector& targetParticle,
                                                       const G4double atomicWeight)

// AntiSigma+ 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.
{
  static const G4double expxu = 82.;     // upper bound for arg. of exp
  static const G4double expxl = -expxu;  // lower bound for arg. of exp

  static const G4double protb = 0.7;
  static const G4double neutb = 0.7;
  static const G4double     c = 1.25;

  static const G4int numMul   = 1200;
  static const G4int numMulAn = 400;
  static const G4int numSec   = 60;

  G4int protonCode  = Proton.getCode();

  G4int targetCode = targetParticle.getCode();
  G4double incidentTotalMomentum = incidentParticle.getTotalMomentum();

  static G4bool first = true;
  static G4double protmul[numMul],  protnorm[numSec];   // proton constants
  static G4double protmulAn[numMulAn],protnormAn[numSec]; 
  static G4double neutmul[numMul],  neutnorm[numSec];   // neutron constants
  static G4double neutmulAn[numMulAn],neutnormAn[numSec];

  //  misc. local variables
  //  npos = number of pi+,  nneg = number of pi-,  nzero = number of pi0

  G4int i, counter, nt, npos, nneg, nzero;

  if (first) {
    // compute normalization constants, this will only be done once
    first = false;
    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,protb,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,neutb,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];
    }

    // annihilation
    for (i = 0; i < numMulAn; i++) protmulAn[i] = 0.0;
    for (i = 0; i < numSec; i++) protnormAn[i] = 0.0;
    counter = -1;
    for (npos = 1; npos < (numSec/3); npos++) {
      nneg = npos; 
      for (nzero = 0; nzero < numSec/3; nzero++) {
        if (++counter < numMulAn) {
          nt = npos+nneg+nzero;
          if ((nt>1) && (nt<=numSec) ) {
            protmulAn[counter] = pmltpc(npos,nneg,nzero,nt,protb,c);
            protnormAn[nt-1] += protmulAn[counter];
          }
        }
      }
    }

    for (i = 0; i < numMulAn; i++) neutmulAn[i]  = 0.0;
    for (i = 0; i < numSec; i++) neutnormAn[i] = 0.0;
    counter = -1;
    for (npos = 0; npos < numSec/3; npos++) {
      nneg = npos+1; 
      for (nzero = 0; nzero < numSec/3; nzero++) {
        if (++counter < numMulAn) {
          nt = npos+nneg+nzero;
          if ((nt>1) && (nt<=numSec) ) {
            neutmulAn[counter] = pmltpc(npos,nneg,nzero,nt,neutb,c);
            neutnormAn[nt-1] += neutmulAn[counter];
          }
        }
      }
    }
    for (i = 0; i < numSec; i++) {
      if( protnormAn[i] > 0.0 )protnormAn[i] = 1.0/protnormAn[i];
      if( neutnormAn[i] > 0.0 )neutnormAn[i] = 1.0/neutnormAn[i];
    }
  }  // end of initialization

         
  // initialize the first two places the same as beam and target                                    
  pv[0] = incidentParticle;
  pv[1] = targetParticle;
  vecLen = 2;

  if (!inElastic) {  // some two-body reactions 
    G4double cech[] = {0.50, 0.45, 0.40, 0.35, 0.30, 0.25, 0.06, 0.04, 0.005, 0.};

    G4int iplab = std::min(9, G4int( incidentTotalMomentum*2.5));
    if (G4UniformRand() < cech[iplab]/std::pow(atomicWeight,0.42) ) {           
      G4double ran = G4UniformRand();

      if (targetCode == protonCode) {
        if (ran < 0.2) {
          pv[0] = Proton;
          pv[1] = AntiSigmaPlus;
        } else if (ran < 0.4) {
          pv[0] = AntiLambda;
          pv[1] = Neutron;
        } else if (ran < 0.6) {
          pv[0] = Neutron;
          pv[1] = AntiLambda;
        } else if (ran < 0.8) {
          pv[0] = Neutron;
          pv[1] = AntiSigmaZero;
        } else {
          pv[0] = AntiSigmaZero;
          pv[1] = Neutron;
        }     
      } else {
        pv[0] = Neutron;
        pv[1] = AntiSigmaPlus;
      }  
    }
   
    return;
  }
  else if (availableEnergy <= PionPlus.getMass()) return;

  // inelastic scattering
  npos = 0; nneg = 0; nzero = 0;
  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( incidentTotalMomentum*10.);
  if ( iplab >  9) iplab = 10 + G4int( (incidentTotalMomentum  -1.)*5. );          
  if ( iplab > 14) iplab = 15 + G4int(  incidentTotalMomentum  -2.     );
  if ( iplab > 22) iplab = 23 + G4int( (incidentTotalMomentum -10.)/10.); 
  iplab = std::min(24, iplab);

  if ( G4UniformRand() > anhl[iplab] ) {  // non- annihilation channels

    // number of total particles vs. centre of mass Energy - 2*proton mass
    G4double aleab = std::log(availableEnergy);
    G4double n = 3.62567+aleab*(0.665843+aleab*(0.336514
                 + aleab*(0.117712+0.0136912*aleab))) - 2.0;
   
    // normalization constant for kno-distribution.
    // calculate first the sum of all constants, check for numerical problems.   
    G4double test, dum, anpn = 0.0;

           for (nt=1; nt<=numSec; nt++) {
             test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
             dum = pi*nt/(2.0*n*n);
             if (std::fabs(dum) < 1.0) { 
               if( test >= 1.0e-10 )anpn += dum*test;
             } else { 
               anpn += dum*test;
             }
           }
   
           G4double ran = G4UniformRand();
           G4double excs = 0.0;
           if( targetCode == protonCode ) 
             {
               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) ) {
                                    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) goto outOfLoop;      //----------------------->
                                  }   
                                }    
                            }     
                       }                                                                                  
                  }
       
                                              // 3 previous loops continued to the end
               inElastic = false;                 // quasi-elastic scattering   
               return;
             }
           else   
             {                                         // target must be a neutron
               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) ) {
                                    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) goto outOfLoop;       // -------------------------->
                                  }
                                }
                            }
                       }
                  }
                                                      // 3 previous loops continued to the end
               inElastic = false;                     // quasi-elastic scattering.
               return;
             }
          
       outOfLoop:           //  <------------------------------------------------------------------------   
    
       ran = G4UniformRand();

       if( targetCode == protonCode)
         {
           if( npos == nneg)
             {
               if (ran < 0.50)
                 {
                 }
               else if (ran < 0.75)
                 {
                   pv[0] = AntiSigmaZero;
                   pv[1] = Neutron;
                 }
               else
                 {
                   pv[0] = AntiLambda;
                   pv[1] = Neutron;
                 } 
             }
           else if (npos == (nneg-1))
             {
               if( ran < 0.50)
                 {
                   pv[0] = AntiLambda;
                 }
               else
                 {
                   pv[0] = AntiSigmaZero;
                 }
             }
           else 
             {  
               pv[1] = Neutron;
             }
         }  
       else
         {
           if( npos == nneg)
             {
             } 
           else if ( npos == (nneg-1))
             {
               if (ran < 0.5)
                 {
                   pv[1] = Proton;
                 }
               else if (ran < 0.75)
                 {
                   pv[0] = AntiLambda;
                 }
               else
                 {
                   pv[0] = AntiSigmaZero;
                 } 
             }
           else 
             {
               if (ran < 0.5)
                 {
                   pv[0] = AntiLambda;
                   pv[1] = Proton;
                 }
               else 
                 {
                   pv[0] = AntiSigmaZero;
                   pv[1] = Proton;
                 }
             }      
         } 
     }
   else                                                               // annihilation
     {  
       if ( availableEnergy > 2. * PionPlus.getMass() )
         {

           G4double aleab = std::log(availableEnergy);
           G4double n     = 3.62567+aleab*(0.665843+aleab*(0.336514
                            + aleab*(0.117712+0.0136912*aleab))) - 2.0;
   
                      //   normalization constant for kno-distribution.
                      //   calculate first the sum of all constants, check for numerical problems.   
           G4double test, dum, anpn = 0.0;

           for (nt=2; nt<=numSec; nt++) {
             test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
             dum = pi*nt/(2.0*n*n);
             if (std::fabs(dum) < 1.0) { 
               if( test >= 1.0e-10 )anpn += dum*test;
             } else { 
               anpn += dum*test;
             }
           }
   
           G4double ran = G4UniformRand();
           G4double excs = 0.0;
           if( targetCode == protonCode ) 
             {
               counter = -1;
               for( npos=1; npos<numSec/3; npos++ ) 
                  {
                    nneg = npos; 
                    for( nzero=0; nzero<numSec/3; nzero++ ) 
                      {
                        if( ++counter < numMulAn ) 
                          {
                            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*protmulAn[counter]*protnormAn[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) goto outOfLoopAn;      //----------------------->
                            }   
                          }    
                      }     
                 }                                                                                  
                 // 3 previous loops continued to the end
               inElastic = false;         // quasi-elastic scattering   
               return;
             }
           else   
             {                                         // target must be a neutron
               counter = -1;
               for( npos=0; npos<numSec/3; npos++ ) 
                 { 
                   nneg = npos+1; 
                   for( nzero=0; nzero<numSec/3; nzero++ ) 
                      {
                        if( ++counter < numMulAn ) 
                          {
                            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*neutmulAn[counter]*neutnormAn[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) goto outOfLoopAn;       // -------------------------->
                            }
                          }
                      }
                 }
               inElastic = false;            // quasi-elastic scattering.
               return;
             }
       outOfLoopAn:           //  <----------------------------------------   
       vecLen = 0;
         }
     }

   nt = npos + nneg + nzero;
   while ( nt > 0)
       {
         G4double ran = G4UniformRand();
         if ( ran < (G4double)npos/nt)
            { 
              if( npos > 0 ) 
                { pv[vecLen++] = PionPlus;
                  npos--;
                }
            }
         else if ( ran < (G4double)(npos+nneg)/nt)
            {   
              if( nneg > 0 )
                { 
                  pv[vecLen++] = PionMinus;
                  nneg--;
                }
            }
         else
            {
              if( nzero > 0 )
                { 
                  pv[vecLen++] = PionZero;
                  nzero--;
                }
            }
         nt = npos + nneg + nzero;
       } 
   if (verboseLevel > 1)
      {
        G4cout << "Particles produced: " ;
        G4cout << pv[0].getName() << " " ;
        G4cout << pv[1].getName() << " " ;
        for (i=2; i < vecLen; i++)   
            { 
              G4cout << pv[i].getName() << " " ;
            }
         G4cout << G4endl;
      }
   return;
 }

---