source: trunk/source/processes/hadronic/models/rpg/src/G4RPGProtonInelastic.cc @ 847

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// $Id: G4RPGProtonInelastic.cc,v 1.1 2007/07/18 21:04:20 dennis Exp $
// GEANT4 tag $Name: geant4-09-01-patch-02 $
//
 
#include "G4RPGProtonInelastic.hh"
#include "Randomize.hh"
 
G4HadFinalState*
G4RPGProtonInelastic::ApplyYourself( const G4HadProjectile &aTrack,
                                     G4Nucleus &targetNucleus )
{
  theParticleChange.Clear();
  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 << "G4RPGProtonInelastic::ApplyYourself called" << G4endl;
    G4cout << "kinetic energy = " 
           << originalIncident->GetKineticEnergy()/MeV << "MeV, ";
    G4cout << "target material = " 
           << targetMaterial->GetName() << ", ";
    G4cout << "target particle = " 
           << originalTarget->GetDefinition()->GetParticleName()
           << G4endl;
  }

  if( originalIncident->GetKineticEnergy()/GeV < 0.01+2.*G4UniformRand()/9. )
  {
    SlowProton( originalIncident, targetNucleus );
    delete originalTarget;
    return &theParticleChange;
  }

  //
  // 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) );
  }
  const G4double cutOff = 0.1;
  if( modifiedOriginal.GetKineticEnergy()/MeV <= cutOff )
  {
    SlowProton( originalIncident, targetNucleus );
    delete originalTarget;
    return &theParticleChange;
  }

  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,256> vec;  // vec will contain the sec. particles
  G4int vecLen = 0;
  vec.Initialize( 0 );

  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 );

  delete originalTarget;
  return &theParticleChange;
}

void
G4RPGProtonInelastic::SlowProton(const G4HadProjectile *originalIncident,
                                 G4Nucleus &targetNucleus )
{
  const G4double A = targetNucleus.GetN();    // atomic weight
  const G4double Z = targetNucleus.GetZ();    // atomic number
//  G4double currentKinetic = originalIncident->GetKineticEnergy()/MeV;
  //
  // calculate Q-value of reactions
  //
  G4double theAtomicMass = targetNucleus.AtomicMass( A, Z );
  G4double massVec[9];
  massVec[0] = targetNucleus.AtomicMass( A+1.0, Z+1.0 );
  massVec[1] = 0.;
  if (A > Z+1.0)
     massVec[1] = targetNucleus.AtomicMass( A    , Z+1.0 );
  massVec[2] = theAtomicMass;
  massVec[3] = 0.;
  if (A > 1.0 && A-1.0 > Z) 
     massVec[3] = targetNucleus.AtomicMass( A-1.0, Z );
  massVec[4] = 0.;
  if (A > 2.0 && A-2.0 > Z) 
     massVec[4] = targetNucleus.AtomicMass( A-2.0, Z     );
  massVec[5] = 0.;
  if (A > 3.0 && Z > 1.0 && A-3.0 > Z-1.0) 
     massVec[5] = targetNucleus.AtomicMass( A-3.0, Z-1.0 );
  massVec[6] = 0.;
  if (A > 1.0 && A-1.0 > Z+1.0) 
     massVec[6] = targetNucleus.AtomicMass( A-1.0, Z+1.0 );
  massVec[7] = massVec[3];
  massVec[8] = 0.;
  if (A > 1.0 && Z > 1.0) 
     massVec[8] = targetNucleus.AtomicMass( A-1.0, Z-1.0 );
    
  G4FastVector<G4ReactionProduct,4> vec;  // vec will contain the secondary particles
  G4int vecLen = 0;
  vec.Initialize( 0 );
    
  twoBody.NuclearReaction( vec, vecLen, originalIncident,
                           targetNucleus, theAtomicMass, massVec );
    
  theParticleChange.SetStatusChange( stopAndKill );
  theParticleChange.SetEnergyChange( 0.0 );
    
  G4DynamicParticle *pd;
  for( G4int i=0; i<vecLen; ++i )
  {
    pd = new G4DynamicParticle();
    pd->SetDefinition( vec[i]->GetDefinition() );
    pd->SetMomentum( vec[i]->GetMomentum() );
    theParticleChange.AddSecondary( pd );
    delete vec[i];
  }
}
 
void G4RPGProtonInelastic::Cascade(
   G4FastVector<G4ReactionProduct,256> &vec,
   G4int &vecLen,
   const G4HadProjectile *originalIncident,
   G4ReactionProduct &currentParticle,
   G4ReactionProduct &targetParticle,
   G4bool &incidentHasChanged,
   G4bool &targetHasChanged,
   G4bool &quasiElastic )
{
  // Derived from H. Fesefeldt's original FORTRAN code CASP
  //
  // Proton 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.
  //
  // The center of mass energy is based on the initial energy, before
  // Fermi motion and evaporation effects are taken into account
  //
  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
  // np = number of pi+, nm = number of pi-, nz = number of pi0
  G4int counter, nt=0, np=0, nm=0, nz=0;
  const G4double c = 1.25;    
  const G4double b[] = { 0.70, 0.35 };
  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( np=0; np<(numSec/3); ++np )
    {
      for( nm=std::max(0,np-2); nm<=np; ++nm )
      {
        for( nz=0; nz<numSec/3; ++nz )
        {
          if( ++counter < numMul )
          {
            nt = np+nm+nz;
            if( nt>0 && nt<=numSec )
            {
              protmul[counter] = Pmltpc(np,nm,nz,nt,b[0],c) /
                (Factorial(2-np+nm)*Factorial(np-nm) );
              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( np=0; np<numSec/3; ++np )
    {
      for( nm=std::max(0,np-1); nm<=(np+1); ++nm )
      {
        for( nz=0; nz<numSec/3; ++nz )
        {
          if( ++counter < numMul )
          {
            nt = np+nm+nz;
            if( nt>0 && nt<=numSec )
            {
              neutmul[counter] = Pmltpc(np,nm,nz,nt,b[1],c) /
                (Factorial(1-np+nm)*Factorial(1+np-nm) );
              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();
  G4int ieab = static_cast<G4int>(availableEnergy*5.0/GeV);
  const G4double supp[] = {0.,0.4,0.55,0.65,0.75,0.82,0.86,0.90,0.94,0.98};
  G4double test, w0, wp, wt, wm;
    if( (availableEnergy < 2.0*GeV) && (G4UniformRand() >= supp[ieab]) )
    {
      // suppress high multiplicity events at low momentum
      // only one pion will be produced
      
      np = nm = nz = 0;
      if( targetParticle.GetDefinition() == aProton )
      {
        test = std::exp( std::min( expxu, std::max(
         expxl, -(1.0+b[0])*(1.0+b[0])/(2.0*c*c) ) ) );
        w0 = test/2.0;
        wp = test;
        if( G4UniformRand() < w0/(w0+wp) )
          nz = 1;
        else
          np = 1;
      }
      else // target is a neutron
      {
        test = std::exp( std::min( expxu, std::max(
         expxl, -(1.0+b[1])*(1.0+b[1])/(2.0*c*c) ) ) );
        w0 = test;
        wp = test/2.0;        
        test = std::exp( std::min( expxu, std::max(
         expxl, -(-1.0+b[1])*(-1.0+b[1])/(2.0*c*c) ) ) );
        wm = test/2.0;
        wt = w0+wp+wm;
        wp += w0;
        G4double ran = G4UniformRand();
        if( ran < w0/wt )
          nz = 1;
        else if( ran < wp/wt )
          np = 1;
        else
          nm = 1;
      }
    }
    else // (availableEnergy >= 2.0*GeV) || (random number < supp[ieab])
    {
      G4double n, anpn;
      GetNormalizationConstant( availableEnergy, n, anpn );
      G4double ran = G4UniformRand();
      G4double dum, excs = 0.0;
      if( targetParticle.GetDefinition() == aProton )
      {
        counter = -1;
        for( np=0; np<numSec/3 && ran>=excs; ++np )
        {
          for( nm=std::max(0,np-2); nm<=np && ran>=excs; ++nm )
          {
            for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
            {
              if( ++counter < numMul )
              {
                nt = np+nm+nz;
                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;
        }
      }
      else  // target must be a neutron
      {
        counter = -1;
        for( np=0; np<numSec/3 && ran>=excs; ++np )
        {
          for( nm=std::max(0,np-1); nm<=(np+1) && ran>=excs; ++nm )
          {
            for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
            {
              if( ++counter < numMul )
              {
                nt = np+nm+nz;
                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;
        }
      }
      np--; nm--; nz--;
    }
    if( targetParticle.GetDefinition() == aProton )
    {
      switch( np-nm )
      {
       case 1:
         if( G4UniformRand() < 0.5 )
         {
           targetParticle.SetDefinitionAndUpdateE( aNeutron );
           targetHasChanged = true;
         } else {
           currentParticle.SetDefinitionAndUpdateE( aNeutron );
           incidentHasChanged = true;
         }
         break;
       case 2:
         currentParticle.SetDefinitionAndUpdateE( aNeutron );
         targetParticle.SetDefinitionAndUpdateE( aNeutron );
         incidentHasChanged = true;
         targetHasChanged = true;
         break;
       default:
         break;
      }
    }
    else  // target is a neutron
    {
      switch( np-nm )
      {
       case 0:
         if( G4UniformRand() < 0.333333 )
         {
           currentParticle.SetDefinitionAndUpdateE( aNeutron );
           targetParticle.SetDefinitionAndUpdateE( aProton );
           incidentHasChanged = true;
           targetHasChanged = true;
         }
         break;
       case 1:
         currentParticle.SetDefinitionAndUpdateE( aNeutron );
         incidentHasChanged = true;
         break;
       default:
         targetParticle.SetDefinitionAndUpdateE( aProton );
         targetHasChanged = true;
         break;
      }
    }
    SetUpPions( np, nm, nz, vec, vecLen );
    return;
  }

 /* end of file */