G4ElasticHNScattering Class Reference

#include <G4ElasticHNScattering.hh>

Public Member Functions
	G4ElasticHNScattering ()
virtual	~G4ElasticHNScattering ()
virtual G4bool	ElasticScattering (G4VSplitableHadron *aPartner, G4VSplitableHadron *bPartner, G4FTFParameters *theParameters) const

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Detailed Description

Definition at line 47 of file G4ElasticHNScattering.hh.

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Constructor & Destructor Documentation

G4ElasticHNScattering::G4ElasticHNScattering

(

)

Definition at line 52 of file G4ElasticHNScattering.cc.

{
}

G4ElasticHNScattering::~G4ElasticHNScattering

(

)

[virtual]

Definition at line 259 of file G4ElasticHNScattering.cc.

{
}

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Member Function Documentation

G4bool G4ElasticHNScattering::ElasticScattering	(	G4VSplitableHadron *	aPartner,
		G4VSplitableHadron *	bPartner,
		G4FTFParameters *	theParameters
	)			const [virtual]

Definition at line 57 of file G4ElasticHNScattering.cc.

References G4VSplitableHadron::Get4Momentum(), G4FTFParameters::GetAvaragePt2ofElasticScattering(), G4VSplitableHadron::GetDefinition(), G4ParticleDefinition::GetPDGMass(), G4VSplitableHadron::GetPosition(), G4VSplitableHadron::GetTimeOfCreation(), G4VSplitableHadron::IncrementCollisionCount(), G4VSplitableHadron::Set4Momentum(), G4VSplitableHadron::SetPosition(), G4VSplitableHadron::SetStatus(), and G4VSplitableHadron::SetTimeOfCreation().

Referenced by G4DiffractiveExcitation::ExciteParticipants().

{
// -------------------- Projectile parameters -----------------------------------
           G4LorentzVector Pprojectile=projectile->Get4Momentum();

           if(Pprojectile.z() < 0.)
           {
            target->SetStatus(2);
            return false;
           } 

           G4bool PutOnMassShell(false);

           G4double M0projectile = Pprojectile.mag();                        
           if(M0projectile < projectile->GetDefinition()->GetPDGMass()) 
           {
              PutOnMassShell=true;
              M0projectile=projectile->GetDefinition()->GetPDGMass();
           }

           G4double Mprojectile2 = M0projectile * M0projectile;

           G4double AveragePt2=theParameters->GetAvaragePt2ofElasticScattering();

// -------------------- Target parameters ----------------------------------------------

           G4LorentzVector Ptarget=target->Get4Momentum();

           G4double M0target = Ptarget.mag();

           if(M0target < target->GetDefinition()->GetPDGMass()) 
           {
              PutOnMassShell=true;
              M0target=target->GetDefinition()->GetPDGMass();
           }
     
           G4double Mtarget2 = M0target * M0target;                      

// Transform momenta to cms and then rotate parallel to z axis;

           G4LorentzVector Psum;
           Psum=Pprojectile+Ptarget;

           G4LorentzRotation toCms(-1*Psum.boostVector());

           G4LorentzVector Ptmp=toCms*Pprojectile;

           if ( Ptmp.pz() <= 0. )                                
           {
           // "String" moving backwards in  CMS, abort collision !!
           //G4cout << " abort Collision!! " << G4endl;
                   target->SetStatus(2);
                   return false; 
           }
                           
           toCms.rotateZ(-1*Ptmp.phi());
           toCms.rotateY(-1*Ptmp.theta());
        
           G4LorentzRotation toLab(toCms.inverse());

           Pprojectile.transform(toCms);
           Ptarget.transform(toCms);

// ---------------------- Putting on mass-on-shell, if needed ------------------------
           G4double PZcms2, PZcms;                                          

           G4double S=Psum.mag2();                                          
//         G4double SqrtS=std::sqrt(S);                                     

           PZcms2=(S*S+Mprojectile2*Mprojectile2+Mtarget2*Mtarget2-
                                 2*S*Mprojectile2-2*S*Mtarget2-2*Mprojectile2*Mtarget2)/4./S;

           if(PZcms2 < 0.)
           {  // It can be in an interaction with off-shell nuclear nucleon
            if(M0projectile > projectile->GetDefinition()->GetPDGMass()) 
            {  // An attempt to de-excite the projectile
               // It is assumed that the target is in the ground state
             M0projectile = projectile->GetDefinition()->GetPDGMass();
             Mprojectile2=M0projectile*M0projectile;
             PZcms2=(S*S+Mprojectile2*Mprojectile2+Mtarget2*Mtarget2-
                    2*S*Mprojectile2 - 2*S*Mtarget2 - 2*Mprojectile2*Mtarget2)
                    /4./S;

             if(PZcms2 < 0.){ return false;} // Non succesful attempt after the de-excitation
            }
            else // if(M0projectile > projectile->GetDefinition()->GetPDGMass())
            {
             target->SetStatus(2);                                   
             return false;                   // The projectile was not excited,
                                             // but the energy was too low to put
                                             // the target nucleon on mass-shell
            }   // end of if(M0projectile > projectile->GetDefinition()->GetPDGMass())
           }    // end of if(PZcms2 < 0.)

           PZcms = std::sqrt(PZcms2);

           if(PutOnMassShell)
           {
              if(Pprojectile.z() > 0.)
              {
                 Pprojectile.setPz( PZcms);
                 Ptarget.setPz(    -PZcms);
              }
              else  // if(Pprojectile.z() > 0.)
              {
                 Pprojectile.setPz(-PZcms);
                 Ptarget.setPz(     PZcms);
              };

              Pprojectile.setE(std::sqrt(Mprojectile2+
                                                      Pprojectile.x()*Pprojectile.x()+
                                                      Pprojectile.y()*Pprojectile.y()+
                                                      PZcms2));
              Ptarget.setE(std::sqrt(    Mtarget2    +
                                                      Ptarget.x()*Ptarget.x()+
                                                      Ptarget.y()*Ptarget.y()+
                                                      PZcms2));
           }  // end of if(PutOnMassShell)

           G4double maxPtSquare = PZcms2;

// ------ Now we can calculate the transfered Pt --------------------------
           G4double Pt2;                                                    
           G4double ProjMassT2; //, ProjMassT;                                  
           G4double TargMassT2; //, TargMassT;

           G4LorentzVector Qmomentum;
           Qmomentum=G4LorentzVector(GaussianPt(AveragePt2,maxPtSquare),0);

           Pt2=G4ThreeVector(Qmomentum.vect()).mag2();                  

           ProjMassT2=Mprojectile2+Pt2;                           
//           ProjMassT =std::sqrt(ProjMassT2);                            

           TargMassT2=Mtarget2+Pt2;                               
//           TargMassT =std::sqrt(TargMassT2);                            

           PZcms2=(S*S+ProjMassT2*ProjMassT2+                           
                       TargMassT2*TargMassT2-                           
                    2.*S*ProjMassT2-2.*S*TargMassT2-                 
                    2.*ProjMassT2*TargMassT2)/4./S;                  
           if(PZcms2 < 0 ) {PZcms2=0;};// to avoid the exactness problem
           PZcms =std::sqrt(PZcms2);                                    

           Pprojectile.setPz( PZcms);  
           Ptarget.setPz(    -PZcms); 

           Pprojectile += Qmomentum;
           Ptarget     -= Qmomentum;

// Transform back and update SplitableHadron Participant.
           Pprojectile.transform(toLab);
           Ptarget.transform(toLab);
/*  // Maybe it will be needed for an exact calculations--------------------
           G4double TargetMomentum=std::sqrt(Ptarget.x()*Ptarget.x()+
                                             Ptarget.y()*Ptarget.y()+
                                             Ptarget.z()*Ptarget.z());
*/

// Calculation of the creation time ---------------------
      projectile->SetTimeOfCreation(target->GetTimeOfCreation());
      projectile->SetPosition(target->GetPosition());
// Creation time and position of target nucleon were determined at
// ReggeonCascade() of G4FTFModel
// ------------------------------------------------------

           projectile->Set4Momentum(Pprojectile);
           target->Set4Momentum(Ptarget);

           projectile->IncrementCollisionCount(1);
           target->IncrementCollisionCount(1);

           return true;
}

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The documentation for this class was generated from the following files:

• G4ElasticHNScattering.hh
• G4ElasticHNScattering.cc

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