G4eeTo3PiModel Class Reference

#include <G4eeTo3PiModel.hh>

Inheritance diagram for G4eeTo3PiModel:

Public Member Functions
	G4eeTo3PiModel (G4eeCrossSections *)
virtual	~G4eeTo3PiModel ()
virtual G4double	ThresholdEnergy () const
virtual G4double	PeakEnergy () const
virtual G4double	ComputeCrossSection (G4double) const
virtual G4PhysicsVector *	PhysicsVector (G4double, G4double) const
virtual void	SampleSecondaries (std::vector< G4DynamicParticle * > *, G4double, const G4ThreeVector &)
Public Member Functions inherited from G4Vee2hadrons
	G4Vee2hadrons ()
virtual	~G4Vee2hadrons ()
void	SetLowEnergy (G4double val)
G4double	LowEnergy () const
void	SetHighEnergy (G4double val)
G4double	HighEnergy () const

Detailed Description

Definition at line 59 of file G4eeTo3PiModel.hh.

Constructor & Destructor Documentation

G4eeTo3PiModel::G4eeTo3PiModel

(

G4eeCrossSections *

cr

)

Definition at line 66 of file G4eeTo3PiModel.cc.

References G4ParticleDefinition::GetPDGMass(), python.hepunit::MeV, G4PionPlus::PionPlus(), and G4PionZero::PionZero().

                                                   :
  cross(cr)
{
  massPi  = G4PionPlus::PionPlus()->GetPDGMass();
  massPi0 = G4PionZero::PionZero()->GetPDGMass();
  massOm  = 782.62*MeV;
  massPhi = 1019.46*MeV;
  gcash   = 0.0;
  gmax    = 1.0;
}

G4eeTo3PiModel::~G4eeTo3PiModel ( )

virtual

Definition at line 79 of file G4eeTo3PiModel.cc.

{}

Member Function Documentation

G4double G4eeTo3PiModel::ComputeCrossSection ( G4double  e ) const

virtual

Implements G4Vee2hadrons.

Definition at line 100 of file G4eeTo3PiModel.cc.

References G4eeCrossSections::CrossSection3pi(), G4Vee2hadrons::HighEnergy(), and G4INCL::Math::min().

{
  G4double ee = std::min(HighEnergy(),e);
  return cross->CrossSection3pi(ee);
}

G4double G4eeTo3PiModel::PeakEnergy ( ) const

virtual

Implements G4Vee2hadrons.

Definition at line 91 of file G4eeTo3PiModel.cc.

References G4Vee2hadrons::HighEnergy().

{
  G4double e = massOm;
  if(HighEnergy() > massPhi) e = massPhi; 
  return e;
}

G4PhysicsVector * G4eeTo3PiModel::PhysicsVector ( G4double  emin, G4double  emax  ) const

virtual

Implements G4Vee2hadrons.

Definition at line 108 of file G4eeTo3PiModel.cc.

References G4INCL::Math::max(), python.hepunit::MeV, G4PhysicsVector::SetSpline(), ThresholdEnergy(), and test::v.

{
  G4double tmin = std::max(emin, ThresholdEnergy());
  G4double tmax = std::max(tmin, emax);
  G4int nbins = (G4int)((tmax - tmin)/(1.*MeV));
  G4PhysicsVector* v = new G4PhysicsLinearVector(emin,emax,nbins);
  v->SetSpline(true);
  return v;
}

void G4eeTo3PiModel::SampleSecondaries ( std::vector< G4DynamicParticle * > *  newp, G4double  e, const G4ThreeVector &  direction  )

virtual

Implements G4Vee2hadrons.

Definition at line 121 of file G4eeTo3PiModel.cc.

References CLHEP::HepLorentzVector::boost(), CLHEP::HepLorentzVector::boostVector(), G4eeCrossSections::DpRho(), G4cout, G4endl, G4RandomDirection(), G4UniformRand, CLHEP::HepLorentzVector::m2(), G4PionMinus::PionMinus(), G4PionPlus::PionPlus(), G4PionZero::PionZero(), CLHEP::HepLorentzVector::rotateUz(), ThresholdEnergy(), CLHEP::Hep3Vector::x(), CLHEP::HepLorentzVector::x(), CLHEP::Hep3Vector::y(), CLHEP::HepLorentzVector::y(), CLHEP::Hep3Vector::z(), and CLHEP::HepLorentzVector::z().

{
  if(e < ThresholdEnergy()) return;

  G4double x0 = massPi0/e;
  G4double x1 = massPi/e;

  G4LorentzVector w0, w1, w2;
  G4ThreeVector dir0, dir1;
  G4double e0, p0, e2, p, gg, m01, m02, m12;

  // max pi0 energy
  G4double edel  = 0.5*e*(1.0 + x0*x0 - 4.0*x1*x1) - massPi0;

  do {
    // pi0 sample
    e0 = edel*G4UniformRand() + massPi0;
    p0 = sqrt(e0 - massPi0*massPi0);
    dir0 = G4RandomDirection();
    w0 = G4LorentzVector(p0*dir0.x(),p0*dir0.y(),p0*dir0.z(),e0);

    // pi+pi- pair
    w1 = G4LorentzVector(-p0*dir0.x(),-p0*dir0.y(),-p0*dir0.z(),e-e0);
    G4ThreeVector bst = w1.boostVector();
    e2 = 0.25*w1.m2();

    // pi+ 
    p = sqrt(e2 - massPi*massPi);
    dir1 = G4RandomDirection();
    w2 = G4LorentzVector(p*dir1.x(),p*dir1.y(),p*dir1.z(),sqrt(e2));
    w2.boost(bst);
    G4double px2 = w2.x();
    G4double py2 = w2.y();
    G4double pz2 = w2.z();

    // pi- 
    w1 -= w2;
    G4double px1 = w1.x();
    G4double py1 = w1.y();
    G4double pz1 = w1.z();

    m01 = w0*w1;
    m02 = w0*w2;
    m12 = w1*w2;

    G4double px = py1*pz2 - py2*pz1;
    G4double py = pz1*px2 - pz2*px1;
    G4double pz = px1*py2 - px2*py1;

    gg = (px*px + py*py + pz*pz)*
      norm( 1.0/cross->DpRho(m01) +  1.0/cross->DpRho(m02)
        + 1.0/cross->DpRho(m12) );
    if(gg > gmax) {
      G4cout << "G4eeTo3PiModel::SampleSecondaries WARNING matrix element g= "
         << gg << " > " << gmax << " (majoranta)" << G4endl;
    }
    if(gg > gcash) gcash = gg;
    
  } while( gmax*G4UniformRand() > gg );

  w0.rotateUz(direction);
  w1.rotateUz(direction);
  w2.rotateUz(direction);

  // create G4DynamicParticle objects 
  G4DynamicParticle* dp0 = 
     new G4DynamicParticle(G4PionZero::PionZero(), w0);
  G4DynamicParticle* dp1 = 
     new G4DynamicParticle(G4PionPlus::PionPlus(), w1);
  G4DynamicParticle* dp2 = 
     new G4DynamicParticle(G4PionMinus::PionMinus(), w2);
  newp->push_back(dp0);
  newp->push_back(dp1);
  newp->push_back(dp2);
}

G4double G4eeTo3PiModel::ThresholdEnergy ( ) const

virtual

Implements G4Vee2hadrons.

Definition at line 84 of file G4eeTo3PiModel.cc.

References G4Vee2hadrons::LowEnergy(), and G4INCL::Math::max().

Referenced by PhysicsVector(), and SampleSecondaries().

{
  return std::max(LowEnergy(),2.0*massPi + massPi0);
}

---

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

• G4eeTo3PiModel.hh
• G4eeTo3PiModel.cc