G4RPGAntiOmegaMinusInelastic.cc

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00025 //
00026 // $Id$
00027 //
00028 //
00029 // NOTE:  The FORTRAN version of the cascade, CASAOM, simply called the
00030 //        routine for the OmegaMinus particle.  Hence, the Cascade function
00031 //        below is just a copy of the Cascade from the OmegaMinus particle.
00032  
00033 #include "G4RPGAntiOmegaMinusInelastic.hh"
00034 #include "G4PhysicalConstants.hh"
00035 #include "G4SystemOfUnits.hh"
00036 #include "Randomize.hh"
00037 
00038 G4HadFinalState*
00039 G4RPGAntiOmegaMinusInelastic::ApplyYourself( const G4HadProjectile &aTrack,
00040                                              G4Nucleus &targetNucleus )
00041 { 
00042   const G4HadProjectile *originalIncident = &aTrack;
00043   if (originalIncident->GetKineticEnergy()<= 0.1*MeV) 
00044   {
00045     theParticleChange.SetStatusChange(isAlive);
00046     theParticleChange.SetEnergyChange(aTrack.GetKineticEnergy());
00047     theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit()); 
00048     return &theParticleChange;      
00049   }
00050 
00051   // create the target particle
00052 
00053   G4DynamicParticle *originalTarget = targetNucleus.ReturnTargetParticle();
00054     
00055     if( verboseLevel > 1 )
00056     {
00057       const G4Material *targetMaterial = aTrack.GetMaterial();
00058       G4cout << "kinetic energy = " << originalIncident->GetKineticEnergy()/MeV << "MeV, ";
00059       G4cout << "target material = " << targetMaterial->GetName() << ", ";
00060       G4cout << "target particle = " << originalTarget->GetDefinition()->GetParticleName()
00061            << G4endl;
00062     }
00063     //
00064     // Fermi motion and evaporation
00065     // As of Geant3, the Fermi energy calculation had not been Done
00066     //
00067     G4double ek = originalIncident->GetKineticEnergy()/MeV;
00068     G4double amas = originalIncident->GetDefinition()->GetPDGMass()/MeV;
00069     G4ReactionProduct modifiedOriginal;
00070     modifiedOriginal = *originalIncident;
00071     
00072     G4double tkin = targetNucleus.Cinema( ek );
00073     ek += tkin;
00074     modifiedOriginal.SetKineticEnergy( ek*MeV );
00075     G4double et = ek + amas;
00076     G4double p = std::sqrt( std::abs((et-amas)*(et+amas)) );
00077     G4double pp = modifiedOriginal.GetMomentum().mag()/MeV;
00078     if( pp > 0.0 )
00079     {
00080       G4ThreeVector momentum = modifiedOriginal.GetMomentum();
00081       modifiedOriginal.SetMomentum( momentum * (p/pp) );
00082     }
00083     //
00084     // calculate black track energies
00085     //
00086     tkin = targetNucleus.EvaporationEffects( ek );
00087     ek -= tkin;
00088     modifiedOriginal.SetKineticEnergy( ek*MeV );
00089     et = ek + amas;
00090     p = std::sqrt( std::abs((et-amas)*(et+amas)) );
00091     pp = modifiedOriginal.GetMomentum().mag()/MeV;
00092     if( pp > 0.0 )
00093     {
00094       G4ThreeVector momentum = modifiedOriginal.GetMomentum();
00095       modifiedOriginal.SetMomentum( momentum * (p/pp) );
00096     }
00097     G4ReactionProduct currentParticle = modifiedOriginal;
00098     G4ReactionProduct targetParticle;
00099     targetParticle = *originalTarget;
00100     currentParticle.SetSide( 1 ); // incident always goes in forward hemisphere
00101     targetParticle.SetSide( -1 );  // target always goes in backward hemisphere
00102     G4bool incidentHasChanged = false;
00103     G4bool targetHasChanged = false;
00104     G4bool quasiElastic = false;
00105     G4FastVector<G4ReactionProduct,GHADLISTSIZE> vec;  // vec will contain the secondary particles
00106     G4int vecLen = 0;
00107     vec.Initialize( 0 );
00108         
00109     const G4double cutOff = 0.1;
00110     const G4double anni = std::min( 1.3*currentParticle.GetTotalMomentum()/GeV, 0.4 );
00111     
00112     if( (currentParticle.GetKineticEnergy()/MeV > cutOff) || (G4UniformRand() > anni) )
00113       Cascade( vec, vecLen,
00114                originalIncident, currentParticle, targetParticle,
00115                incidentHasChanged, targetHasChanged, quasiElastic );
00116     
00117     CalculateMomenta( vec, vecLen,
00118                       originalIncident, originalTarget, modifiedOriginal,
00119                       targetNucleus, currentParticle, targetParticle,
00120                       incidentHasChanged, targetHasChanged, quasiElastic );
00121     
00122     SetUpChange( vec, vecLen,
00123                  currentParticle, targetParticle,
00124                  incidentHasChanged );
00125     
00126   delete originalTarget;
00127   return &theParticleChange;
00128 }
00129 
00130 
00131 void
00132 G4RPGAntiOmegaMinusInelastic::Cascade(G4FastVector<G4ReactionProduct,GHADLISTSIZE> &vec,
00133                                       G4int& vecLen,
00134                                       const G4HadProjectile* originalIncident,
00135                                       G4ReactionProduct& currentParticle,
00136                                       G4ReactionProduct& targetParticle,
00137                                       G4bool& incidentHasChanged,
00138                                       G4bool& targetHasChanged,
00139                                       G4bool& quasiElastic)
00140 {
00141   // Derived from H. Fesefeldt's original FORTRAN code CASOM
00142   // AntiOmegaMinus undergoes interaction with nucleon within a nucleus.  Check if it is
00143   // energetically possible to produce pions/kaons.  In not, assume nuclear excitation
00144   // occurs and input particle is degraded in energy. No other particles are produced.
00145   // If reaction is possible, find the correct number of pions/protons/neutrons
00146   // produced using an interpolation to multiplicity data.  Replace some pions or
00147   // protons/neutrons by kaons or strange baryons according to the average
00148   // multiplicity per Inelastic reaction.
00149 
00150   const G4double mOriginal = originalIncident->GetDefinition()->GetPDGMass()/MeV;
00151   const G4double etOriginal = originalIncident->GetTotalEnergy()/MeV;
00152   const G4double targetMass = targetParticle.GetMass()/MeV;
00153   G4double centerofmassEnergy = std::sqrt( mOriginal*mOriginal +
00154                                       targetMass*targetMass +
00155                                       2.0*targetMass*etOriginal );
00156   G4double availableEnergy = centerofmassEnergy-(targetMass+mOriginal);
00157   if (availableEnergy <= G4PionPlus::PionPlus()->GetPDGMass()/MeV) {
00158     // not energetically possible to produce pion(s)
00159     quasiElastic = true;
00160     return;
00161   }
00162   static G4bool first = true;
00163   const G4int numMul = 1200;
00164   const G4int numSec = 60;
00165   static G4double protmul[numMul], protnorm[numSec]; // proton constants
00166   static G4double neutmul[numMul], neutnorm[numSec]; // neutron constants
00167 
00168   // np = number of pi+, nneg = number of pi-, nz = number of pi0
00169   G4int counter, nt=0, np=0, nneg=0, nz=0;
00170   G4double test;
00171   const G4double c = 1.25;    
00172   const G4double b[] = { 0.7, 0.7 };
00173   if (first) {  // Computation of normalization constants will only be done once
00174     first = false;
00175     G4int i;
00176     for( i=0; i<numMul; ++i )protmul[i] = 0.0;
00177     for( i=0; i<numSec; ++i )protnorm[i] = 0.0;
00178     counter = -1;
00179     for( np=0; np<(numSec/3); ++np )
00180       {
00181         for( nneg=std::max(0,np-1); nneg<=(np+1); ++nneg )
00182         {
00183           for( nz=0; nz<numSec/3; ++nz )
00184           {
00185             if( ++counter < numMul )
00186             {
00187               nt = np+nneg+nz;
00188               if( nt>0 && nt<=numSec )
00189               {
00190                 protmul[counter] = Pmltpc(np,nneg,nz,nt,b[0],c);
00191                 protnorm[nt-1] += protmul[counter];
00192               }
00193             }
00194           }
00195         }
00196       }
00197       for( i=0; i<numMul; ++i )neutmul[i] = 0.0;
00198       for( i=0; i<numSec; ++i )neutnorm[i] = 0.0;
00199       counter = -1;
00200       for( np=0; np<numSec/3; ++np )
00201       {
00202         for( nneg=np; nneg<=(np+2); ++nneg )
00203         {
00204           for( nz=0; nz<numSec/3; ++nz )
00205           {
00206             if( ++counter < numMul )
00207             {
00208               nt = np+nneg+nz;
00209               if( nt>0 && nt<=numSec )
00210               {
00211                 neutmul[counter] = Pmltpc(np,nneg,nz,nt,b[1],c);
00212                 neutnorm[nt-1] += neutmul[counter];
00213               }
00214             }
00215           }
00216         }
00217       }
00218       for( i=0; i<numSec; ++i )
00219       {
00220         if( protnorm[i] > 0.0 )protnorm[i] = 1.0/protnorm[i];
00221         if( neutnorm[i] > 0.0 )neutnorm[i] = 1.0/neutnorm[i];
00222       }
00223     }   // end of initialization
00224     
00225     const G4double expxu = 82.;           // upper bound for arg. of exp
00226     const G4double expxl = -expxu;        // lower bound for arg. of exp
00227     G4ParticleDefinition *aNeutron = G4Neutron::Neutron();
00228     G4ParticleDefinition *aProton = G4Proton::Proton();
00229     G4ParticleDefinition *aKaonMinus = G4KaonMinus::KaonMinus();
00230     G4ParticleDefinition *aSigmaPlus = G4SigmaPlus::SigmaPlus();
00231     G4ParticleDefinition *aXiZero = G4XiZero::XiZero();
00232     G4double n, anpn;
00233     GetNormalizationConstant( availableEnergy, n, anpn );
00234     G4double ran = G4UniformRand();
00235     G4double dum, excs = 0.0;
00236     G4int nvefix = 0;
00237     if( targetParticle.GetDefinition() == aProton )
00238     {
00239       counter = -1;
00240       for( np=0; np<numSec/3 && ran>=excs; ++np )
00241       {
00242         for( nneg=std::max(0,np-1); nneg<=(np+1) && ran>=excs; ++nneg )
00243         {
00244           for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
00245           {
00246             if( ++counter < numMul )
00247             {
00248               nt = np+nneg+nz;
00249               if( nt>0 && nt<=numSec )
00250               {
00251                 test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
00252                 dum = (pi/anpn)*nt*protmul[counter]*protnorm[nt-1]/(2.0*n*n);
00253                 if( std::fabs(dum) < 1.0 )
00254                 {
00255                   if( test >= 1.0e-10 )excs += dum*test;
00256                 }
00257                 else
00258                   excs += dum*test;
00259               }
00260             }
00261           }
00262         }
00263       }
00264       if( ran >= excs )  // 3 previous loops continued to the end
00265       {
00266         quasiElastic = true;
00267         return;
00268       }
00269       np--; nneg--; nz--;
00270       //
00271       // number of secondary mesons determined by kno distribution
00272       // check for total charge of final state mesons to determine
00273       // the kind of baryons to be produced, taking into account
00274       // charge and strangeness conservation
00275       //
00276       if( np < nneg )
00277       {
00278         if( np+1 == nneg )
00279         {
00280           currentParticle.SetDefinitionAndUpdateE( aXiZero );
00281           incidentHasChanged = true;
00282           nvefix = 1;
00283         }
00284         else   // charge mismatch
00285         {
00286           currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
00287           incidentHasChanged = true;
00288           nvefix = 2;
00289         }
00290       }
00291       else if( np > nneg )
00292       {
00293         targetParticle.SetDefinitionAndUpdateE( aNeutron );
00294         targetHasChanged = true;
00295       }
00296     }
00297     else  // target must be a neutron
00298     {
00299       counter = -1;
00300       for( np=0; np<numSec/3 && ran>=excs; ++np )
00301       {
00302         for( nneg=np; nneg<=(np+2) && ran>=excs; ++nneg )
00303         {
00304           for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
00305           {
00306             if( ++counter < numMul )
00307             {
00308               nt = np+nneg+nz;
00309               if( nt>0 && nt<=numSec )
00310               {
00311                 test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
00312                 dum = (pi/anpn)*nt*neutmul[counter]*neutnorm[nt-1]/(2.0*n*n);
00313                 if( std::fabs(dum) < 1.0 )
00314                 {
00315                   if( test >= 1.0e-10 )excs += dum*test;
00316                 }
00317                 else
00318                   excs += dum*test;
00319               }
00320             }
00321           }
00322         }
00323       }
00324       if( ran >= excs )  // 3 previous loops continued to the end
00325       {
00326         quasiElastic = true;
00327         return;
00328       }
00329       np--; nneg--; nz--;
00330       if( np+1 < nneg )
00331       {
00332         if( np+2 == nneg )
00333         {
00334           currentParticle.SetDefinitionAndUpdateE( aXiZero );
00335           incidentHasChanged = true;
00336           nvefix = 1;
00337         }
00338         else   // charge mismatch
00339         {
00340           currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
00341           incidentHasChanged = true;
00342           nvefix = 2;
00343         }
00344         targetParticle.SetDefinitionAndUpdateE( aProton );
00345         targetHasChanged = true;
00346       }
00347       else if( np+1 == nneg )
00348       {
00349         targetParticle.SetDefinitionAndUpdateE( aProton );
00350         targetHasChanged = true;
00351       }
00352   }
00353 
00354   SetUpPions(np, nneg, nz, vec, vecLen);
00355   for (G4int i = 0; i < vecLen && nvefix > 0; ++i) {
00356     if (vec[i]->GetDefinition() == G4PionMinus::PionMinus() ) {
00357       // correct the strangeness by replacing a pi- by a kaon-
00358       if( nvefix >= 1 )vec[i]->SetDefinitionAndUpdateE( aKaonMinus );
00359       --nvefix;
00360     }
00361   }
00362 
00363   return;
00364 }
00365 
00366  /* end of file */
00367  

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