G4Scatterer.cc

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// $Id: G4Scatterer.cc,v 1.16 2010-03-12 15:45:18 gunter Exp $ //
//

#include <vector>

#include "globals.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4ios.hh"
#include "G4Scatterer.hh"
#include "G4KineticTrack.hh"
#include "G4ThreeVector.hh"
#include "G4LorentzRotation.hh"
#include "G4LorentzVector.hh"

#include "G4CollisionNN.hh"
#include "G4CollisionPN.hh"
#include "G4CollisionMesonBaryon.hh"

#include "G4CollisionInitialState.hh"
#include "G4HadTmpUtil.hh"
#include "G4Pair.hh"

// Declare the categories of collisions the Scatterer can handle
typedef GROUP2(G4CollisionNN, G4CollisionMesonBaryon) theChannels;

//----------------------------------------------------------------------------

G4Scatterer::G4Scatterer()
{
  Register aR;
  G4ForEach<theChannels>::Apply(&aR, &collisions);
}

//----------------------------------------------------------------------------

G4Scatterer::~G4Scatterer()
{
  std::for_each(collisions.begin(), collisions.end(), G4Delete());
  collisions.clear();
}

//----------------------------------------------------------------------------

G4double G4Scatterer::GetTimeToInteraction(const G4KineticTrack& trk1,
                                           const G4KineticTrack& trk2)
{
  G4double time = DBL_MAX;
    G4double distance_fast;
  G4LorentzVector mom1 = trk1.GetTrackingMomentum();
//  G4cout << "zcomp=" << std::abs(mom1.vect().unit().z() -1 ) << G4endl;
  G4double collisionTime;

  if ( std::abs(mom1.vect().unit().z() -1 ) < 1e-6 )
  {
     G4ThreeVector position = trk2.GetPosition() - trk1.GetPosition();
     G4double deltaz=position.z();
     G4double velocity = mom1.z()/mom1.e() * c_light;

     collisionTime=deltaz/velocity;
     distance_fast=position.x()*position.x() + position.y()*position.y();
  } else {

    //  The nucleons of the nucleus are FROZEN, ie. do not move..

    G4ThreeVector position = trk2.GetPosition() - trk1.GetPosition();

    G4ThreeVector velocity = mom1.vect()/mom1.e() * c_light;  // mom1.boostVector() will exit on slightly negative mass
    collisionTime = (position * velocity) / velocity.mag2();    // can't divide by /c_light;
    position -= velocity * collisionTime;
    distance_fast=position.mag2();

//    if ( collisionTime>0 ) G4cout << " dis1/2 square" << dis1 <<" "<< dis2 << G4endl;
//     collisionTime = GetTimeToClosestApproach(trk1,trk2);
  }
     if (collisionTime > 0)
        {
           static const G4double maxCrossSection = 500*millibarn;
           if(0.7*pi*distance_fast>maxCrossSection) return time;


           G4LorentzVector mom2(0,0,0,trk2.Get4Momentum().mag());

//         G4ThreeVector momLab = mom1.vect();// frozen Nucleus - mom2.vect();
//         G4ThreeVector posLab = trk1.GetPosition() - trk2.GetPosition();
//         G4double disLab=posLab * posLab - (posLab*momLab) * (posLab*momLab) /(momLab.mag2());

           G4LorentzRotation toCMSFrame((-1)*(mom1 + mom2).boostVector());
           mom1 = toCMSFrame * mom1;
           mom2 = toCMSFrame * mom2;

           G4LorentzVector coordinate1(trk1.GetPosition(), 100.);
           G4LorentzVector coordinate2(trk2.GetPosition(), 100.);
           G4ThreeVector pos = ((toCMSFrame * coordinate1).vect() -
                                (toCMSFrame * coordinate2).vect());

           G4ThreeVector mom = mom1.vect() - mom2.vect();

          // Calculate the impact parameter

           G4double distance = pos * pos - (pos*mom) * (pos*mom) / (mom.mag2());

//     G4cout << " disDiff " << distance-disLab << " " << disLab
//            << " " << std::abs(distance-disLab)/distance << G4endl
//          << " mom/Lab " << mom << " " << momLab << G4endl
//          << " pos/Lab " << pos << " " << posLab
//          << G4endl;

           if(pi*distance>maxCrossSection) return time;

           // charged particles special
           static const G4double maxChargedCrossSection = 200*millibarn;
           if(std::abs(trk1.GetDefinition()->GetPDGCharge())>0.1 &&
              std::abs(trk2.GetDefinition()->GetPDGCharge())>0.1 &&
              pi*distance>maxChargedCrossSection) return time;

           G4double sqrtS = (trk1.Get4Momentum() + trk2.Get4Momentum()).mag();
           // neutrons special  pn is largest cross-section, but above 1.91 GeV is less than 200 mb
           if(( trk1.GetDefinition() == G4Neutron::Neutron() ||
                trk2.GetDefinition() == G4Neutron::Neutron() ) &&
                     sqrtS>1.91*GeV && pi*distance>maxChargedCrossSection) return time;

/*
 *        if(distance <= sqr(1.14*fermi))
 *        {
 *          time = collisionTime;
 *
 * *
 *  *        G4cout << "Scatter distance/time: " << std::sqrt(distance)/fermi <<
 *  *            " / "<< time/ns << G4endl;
 *  *         G4ThreeVector pos1=trk1.GetPosition();
 *  *         G4ThreeVector pos2=trk2.GetPosition();
 *  *         G4LorentzVector xmom1 = trk1.Get4Momentum();
 *  *         G4LorentzVector xmom2 = trk2.Get4Momentum();
 *  *         G4cout << "position1: " <<  pos1.x() << " " << pos1.y() << " "
 *  *                   << pos1.z();
 *  *         pos1+=(collisionTime*c_light/xmom1.e())*xmom1.vect();
 *  *         G4cout << " straight line trprt: "
 *  *                   <<  pos1.x() << " " << pos1.y() << " "
 *  *                   <<  pos1.z()  << G4endl;
 *  *         G4cout << "position2: " <<  pos2.x() << " " << pos2.y() << " "
 *  *                   << pos2.z()  << G4endl;
 *  *         G4cout << "straight line distance 2 fixed:" << (pos1-pos2).mag()/fermi << G4endl;
 *  *         pos2+= (collisionTime*c_light/xmom2.e())*xmom2.vect();
 *  *         G4cout<< " straight line trprt: "
 *  *                   <<  pos2.x() << " " << pos2.y() << " "
 *  *                   <<  pos2.z() << G4endl;
 *  *         G4cout << "straight line distance :" << (pos1-pos2).mag()/fermi << G4endl;
 *  *
 *        }
 *
 *        if(1)
 *          return time;
 */

           if ((trk1.GetActualMass()+trk2.GetActualMass()) > sqrtS) return time;



          G4VCollision* collision = FindCollision(trk1,trk2);
          G4double totalCrossSection;
          // The cross section is interpreted geometrically as an area
          // Two particles are assumed to collide if their distance is < (totalCrossSection/pi)

          if (collision != 0)
            {
              totalCrossSection = collision->CrossSection(trk1,trk2);
              if ( totalCrossSection > 0 )
                {
/*                  G4cout << " totalCrossection = "<< totalCrossSection << ", trk1/2, s, e-m: "
 *                         << trk1.GetDefinition()->GetParticleName()
 *                         << " / "
 *                         << trk2.GetDefinition()->GetParticleName()
 *                         << ", "
 *                         << (trk1.Get4Momentum()+trk2.Get4Momentum()).mag()
 *                         << ", "
 *                         << (trk1.Get4Momentum()+trk2.Get4Momentum()).mag()-
 *                             trk1.Get4Momentum().mag() - trk2.Get4Momentum().mag()
 *                         << G4endl;
 */
                 if (distance <= totalCrossSection / pi)
                   {
                     time = collisionTime;
                   }
                } else
                {

                 // For debugging...
 //                 G4cout << " totalCrossection = 0, trk1/2, s, e-m: "
 //                        << trk1.GetDefinition()->GetParticleName()
 //                        << " / "
 //                        << trk2.GetDefinition()->GetParticleName()
 //                        << ", "
 //                        << (trk1.Get4Momentum()+trk2.Get4Momentum()).mag()
 //                        << ", "
 //                        << (trk1.Get4Momentum()+trk2.Get4Momentum()).mag()-
 //                            trk1.Get4Momentum().mag() - trk2.Get4Momentum().mag()
 //                        << G4endl;

                }
/*
 *            if(distance <= sqr(5.*fermi))
 *             {
 *                G4cout << " distance,xsect, std::sqrt(xsect/pi) : " << std::sqrt(distance)/fermi
 *                       << " " << totalCrossSection/sqr(fermi)
 *                       << " " << std::sqrt(totalCrossSection / pi)/fermi << G4endl;
 *             }
 */

            }
          else
            {
              time = DBL_MAX;
//            /*
              // For debugging
//hpw                 G4cout << "G4Scatterer - collision not found: "
//hpw                << trk1.GetDefinition()->GetParticleName()
//hpw                << " - "
//hpw                << trk2.GetDefinition()->GetParticleName()
//hpw                << G4endl;
              // End of debugging
//            */
            }
        }

      else
        {
              /*
          // For debugging
          G4cout << "G4Scatterer - negative collisionTime"
                 << ": collisionTime = " << collisionTime
                 << ", position = " << position
                 << ", velocity = " << velocity
                 << G4endl;
          // End of debugging
              */
        }

  return time;
}

//----------------------------------------------------------------------------

G4KineticTrackVector* G4Scatterer::Scatter(const G4KineticTrack& trk1,
                                              const G4KineticTrack& trk2)
{
//   G4double sqrtS = (trk1.Get4Momentum() + trk2.Get4Momentum()).mag();
   G4LorentzVector pInitial=trk1.Get4Momentum() + trk2.Get4Momentum();
   G4double energyBalance = pInitial.t();
   G4double pxBalance = pInitial.vect().x();
   G4double pyBalance = pInitial.vect().y();
   G4double pzBalance = pInitial.vect().z();
   G4int chargeBalance = G4lrint(trk1.GetDefinition()->GetPDGCharge()
                       + trk2.GetDefinition()->GetPDGCharge());
   G4int baryonBalance = trk1.GetDefinition()->GetBaryonNumber()
                       + trk2.GetDefinition()->GetBaryonNumber();

   G4VCollision* collision = FindCollision(trk1,trk2);
   if (collision != 0)
   {
     G4double aCrossSection = collision->CrossSection(trk1,trk2);
     if (aCrossSection > 0.0)
     {


        #ifdef debug_G4Scatterer
        G4cout << "be4 FinalState 1(p,e,m): "
        << trk1.Get4Momentum() << " "
        << trk1.Get4Momentum().mag()
        << ", 2: "
        << trk2.Get4Momentum()<< " "
        << trk2.Get4Momentum().mag() << " "
        << G4endl;
        #endif


       G4KineticTrackVector* products = collision->FinalState(trk1,trk2);
       if(!products || products->size() == 0) return products;

        #ifdef debug_G4Scatterer
       G4cout << "size of FS: "<<products->size()<<G4endl;
        #endif

       G4KineticTrack *final= products->operator[](0);


        #ifdef debug_G4Scatterer
        G4cout << "    FinalState 1: "
                << final->Get4Momentum()<< " "
                << final->Get4Momentum().mag() ;
        #endif

        if(products->size() == 1) return products;
        final=products->operator[](1);
        #ifdef debug_G4Scatterer
        G4cout << ", 2: "
                << final->Get4Momentum() << " "
                << final->Get4Momentum().mag() << " " << G4endl;
        #endif

       final= products->operator[](0);
       G4LorentzVector pFinal=final->Get4Momentum();
       if(products->size()==2)
       {
         final=products->operator[](1);
         pFinal +=final->Get4Momentum();
       }

       #ifdef debug_G4Scatterer
       if ( (pInitial-pFinal).mag() > 0.1*MeV )
       {
          G4cout << "G4Scatterer: momentum imbalance, pInitial= " <<pInitial << " pFinal= " <<pFinal<< G4endl;
       }
       G4cout << "Scatterer costh= " << trk1.Get4Momentum().vect().unit() *(products->operator[](0))->Get4Momentum().vect().unit()<< G4endl;
       #endif

       for(size_t hpw=0; hpw<products->size(); hpw++)
       {
         energyBalance-=products->operator[](hpw)->Get4Momentum().t();
         pxBalance-=products->operator[](hpw)->Get4Momentum().vect().x();
         pyBalance-=products->operator[](hpw)->Get4Momentum().vect().y();
         pzBalance-=products->operator[](hpw)->Get4Momentum().vect().z();
         chargeBalance-=G4lrint(products->operator[](hpw)->GetDefinition()->GetPDGCharge());
         baryonBalance-=products->operator[](hpw)->GetDefinition()->GetBaryonNumber();
       }
       if(getenv("ScattererEnergyBalanceCheck"))
         std::cout << "DEBUGGING energy balance A: "
                   <<energyBalance<<" "
                   <<pxBalance<<" "
                   <<pyBalance<<" "
                   <<pzBalance<<" "
                   <<chargeBalance<<" "
                   <<baryonBalance<<" "
                   <<G4endl;
       if(chargeBalance !=0 )
       {
         G4cout << "track 1"<<trk1.GetDefinition()->GetParticleName()<<G4endl;
         G4cout << "track 2"<<trk2.GetDefinition()->GetParticleName()<<G4endl;
         for(size_t hpw=0; hpw<products->size(); hpw++)
         {
            G4cout << products->operator[](hpw)->GetDefinition()->GetParticleName()<<G4endl;
         }
         G4Exception("G4Scatterer", "im_r_matrix001", FatalException,
             "Problem in ChargeBalance");
       }
       return products;
     }
   }

   return NULL;
}

//----------------------------------------------------------------------------

G4VCollision* G4Scatterer::FindCollision(const G4KineticTrack& trk1,
                                         const G4KineticTrack& trk2)
{
  G4VCollision* collisionInCharge = 0;

  size_t i;
  for (i=0; i<collisions.size(); i++)
    {
      G4VCollision* component = collisions[i];
      if (component->IsInCharge(trk1,trk2))
        {
          collisionInCharge = component;
          break;
        }
    }
//    if(collisionInCharge)
//    {
//      G4cout << "found collision : "
//         << collisionInCharge->GetName()<< " "
//      << "for "
//      << trk1.GetDefinition()->GetParticleName()<<" + "
//      << trk2.GetDefinition()->GetParticleName()<<" "
//      << G4endl;;
//    }
  return collisionInCharge;
}

//----------------------------------------------------------------------------

G4double G4Scatterer::GetCrossSection(const G4KineticTrack& trk1,
                                      const G4KineticTrack& trk2)
{
   G4VCollision* collision = FindCollision(trk1,trk2);
   G4double aCrossSection = 0;
   if (collision != 0)
   {
     aCrossSection = collision->CrossSection(trk1,trk2);
   }
   return aCrossSection;
}

//----------------------------------------------------------------------------

const std::vector<G4CollisionInitialState *> & G4Scatterer::
GetCollisions(G4KineticTrack * aProjectile,
              std::vector<G4KineticTrack *> & someCandidates,
              G4double aCurrentTime)
{
  theCollisions.clear();
  std::vector<G4KineticTrack *>::iterator j=someCandidates.begin();
  for(; j != someCandidates.end(); ++j)
  {
    G4double collisionTime = GetTimeToInteraction(*aProjectile, **j);
    if(collisionTime == DBL_MAX)  // no collision
    {
      continue;
    }
    G4KineticTrackVector aTarget;
    aTarget.push_back(*j);
    theCollisions.push_back(
      new G4CollisionInitialState(collisionTime+aCurrentTime, aProjectile, aTarget, this) );
//      G4cerr <<" !!!!!! debug collisions "<<collisionTime<<" "<<pkt->GetDefinition()->GetParticleName()<<G4endl;
   }
   return theCollisions;
}


G4KineticTrackVector * G4Scatterer::
GetFinalState(G4KineticTrack * aProjectile,
              std::vector<G4KineticTrack *> & theTargets)
{
    G4KineticTrack target_reloc(*(theTargets[0]));
    return Scatter(*aProjectile, target_reloc);
}
//----------------------------------------------------------------------------