G4ReactionKinematics Class Reference

#include <G4ReactionKinematics.hh>

Public Member Functions
void	TwoBodyScattering (const G4DynamicParticle *pIn1, const G4DynamicParticle *pIn2, G4DynamicParticle *pOut1, G4DynamicParticle *pOut2)
G4double	BreakupMomentum (G4double totalMass, G4double m1, G4double m2)

Detailed Description

Definition at line 48 of file G4ReactionKinematics.hh.

Member Function Documentation

G4double G4ReactionKinematics::BreakupMomentum ( G4double  totalMass, G4double  m1, G4double  m2  )

inline

Definition at line 57 of file G4ReactionKinematics.hh.

Referenced by TwoBodyScattering().

                                                             {

// is aequivalent to  G4double G4PhaseSpaceDecayChannel::Pmx !!

     G4double m0squared=totalMass*totalMass;
     G4double breakupMomentumSquared=
         (m0squared-(massA+massB)*(massA+massB))*
         (m0squared-(massA-massB)*(massA-massB))/
         (4*m0squared);
    if (breakupMomentumSquared>0) return std::sqrt(breakupMomentumSquared);
    else       return -1.;
}        

void G4ReactionKinematics::TwoBodyScattering	(	const G4DynamicParticle *	pIn1,
		const G4DynamicParticle *	pIn2,
		G4DynamicParticle *	pOut1,
		G4DynamicParticle *	pOut2
	)

Definition at line 41 of file G4ReactionKinematics.cc.

References CLHEP::HepLorentzVector::boost(), BreakupMomentum(), G4UniformRand, G4DynamicParticle::Get4Momentum(), G4DynamicParticle::GetMass(), G4INCL::KinematicsUtils::invariantMass(), python.hepunit::pi, and G4DynamicParticle::Set4Momentum().

{           
// initial particles:

// - total invariant mass
   G4LorentzVector sumIn(pIn1->Get4Momentum()+pIn2->Get4Momentum());
   G4double invariantMass=sumIn.mag();

// - beta of center-of-mass system
   G4ThreeVector betaCMS=sumIn.boostVector();

// final particles:

// - get final particle masses
   G4double massOut1=pOut1->GetMass();
   G4double massOut2=pOut2->GetMass();

// - calculate breakup momentum:
   G4double breakupMomentum=BreakupMomentum(invariantMass, massOut1, massOut2);

// - isotropic decay angle
   G4double costheta = 2.0*G4UniformRand() - 1.0;
   G4double sintheta = std::sqrt(1.0 - costheta*costheta);
   G4double phi = 2.0*pi*G4UniformRand();

// - setup LorentzVectors
   G4double pz=costheta*breakupMomentum;
   G4double px=sintheta*std::cos(phi)*breakupMomentum;
   G4double py=sintheta*std::sin(phi)*breakupMomentum;
   
   G4double breakupMomentumSquared=breakupMomentum*breakupMomentum;
   G4double energy1=std::sqrt(breakupMomentumSquared+massOut1*massOut1);
   G4double energy2=std::sqrt(breakupMomentumSquared+massOut2*massOut2);

   G4LorentzVector lorentz1(px, py, pz, energy1);
   G4LorentzVector lorentz2(px, py, pz, energy2);

// - back into lab system

   lorentz1.boost(betaCMS);
   lorentz2.boost(betaCMS);

// fill in new particles:

   pOut1->Set4Momentum(lorentz1);
   pOut2->Set4Momentum(lorentz2);

   return;
}

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

• G4ReactionKinematics.hh
• G4ReactionKinematics.cc