G4eeTo3PiModel Class Reference

#include <G4eeTo3PiModel.hh>

Inheritance diagram for G4eeTo3PiModel:

G4Vee2hadrons

Public Member Functions

 G4eeTo3PiModel (G4eeCrossSections *)
virtual ~G4eeTo3PiModel ()
virtual G4double ThresholdEnergy () const
virtual G4double PeakEnergy () const
virtual G4double ComputeCrossSection (G4double) const
virtual G4PhysicsVectorPhysicsVector (G4double, G4double) const
virtual void SampleSecondaries (std::vector< G4DynamicParticle * > *, G4double, const G4ThreeVector &)

Detailed Description

Definition at line 59 of file G4eeTo3PiModel.hh.


Constructor & Destructor Documentation

G4eeTo3PiModel::G4eeTo3PiModel ( G4eeCrossSections  ) 

Definition at line 66 of file G4eeTo3PiModel.cc.

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

00066                                                    :
00067   cross(cr)
00068 {
00069   massPi  = G4PionPlus::PionPlus()->GetPDGMass();
00070   massPi0 = G4PionZero::PionZero()->GetPDGMass();
00071   massOm  = 782.62*MeV;
00072   massPhi = 1019.46*MeV;
00073   gcash   = 0.0;
00074   gmax    = 1.0;
00075 }

G4eeTo3PiModel::~G4eeTo3PiModel (  )  [virtual]

Definition at line 79 of file G4eeTo3PiModel.cc.

00080 {}


Member Function Documentation

G4double G4eeTo3PiModel::ComputeCrossSection ( G4double   )  const [virtual]

Implements G4Vee2hadrons.

Definition at line 100 of file G4eeTo3PiModel.cc.

References G4eeCrossSections::CrossSection3pi(), and G4Vee2hadrons::HighEnergy().

00101 {
00102   G4double ee = std::min(HighEnergy(),e);
00103   return cross->CrossSection3pi(ee);
00104 }

G4double G4eeTo3PiModel::PeakEnergy (  )  const [virtual]

Implements G4Vee2hadrons.

Definition at line 91 of file G4eeTo3PiModel.cc.

References G4Vee2hadrons::HighEnergy().

00092 {
00093   G4double e = massOm;
00094   if(HighEnergy() > massPhi) e = massPhi; 
00095   return e;
00096 }

G4PhysicsVector * G4eeTo3PiModel::PhysicsVector ( G4double  ,
G4double   
) const [virtual]

Implements G4Vee2hadrons.

Definition at line 108 of file G4eeTo3PiModel.cc.

References G4PhysicsVector::SetSpline(), and ThresholdEnergy().

00110 {
00111   G4double tmin = std::max(emin, ThresholdEnergy());
00112   G4double tmax = std::max(tmin, emax);
00113   G4int nbins = (G4int)((tmax - tmin)/(1.*MeV));
00114   G4PhysicsVector* v = new G4PhysicsLinearVector(emin,emax,nbins);
00115   v->SetSpline(true);
00116   return v;
00117 }

void G4eeTo3PiModel::SampleSecondaries ( std::vector< G4DynamicParticle * > *  ,
G4double  ,
const G4ThreeVector  
) [virtual]

Implements G4Vee2hadrons.

Definition at line 121 of file G4eeTo3PiModel.cc.

References G4eeCrossSections::DpRho(), G4cout, G4endl, G4RandomDirection(), G4UniformRand, G4PionMinus::PionMinus(), G4PionPlus::PionPlus(), G4PionZero::PionZero(), and ThresholdEnergy().

00123 {
00124   if(e < ThresholdEnergy()) return;
00125 
00126   G4double x0 = massPi0/e;
00127   G4double x1 = massPi/e;
00128 
00129   G4LorentzVector w0, w1, w2;
00130   G4ThreeVector dir0, dir1;
00131   G4double e0, p0, e2, p, gg, m01, m02, m12;
00132 
00133   // max pi0 energy
00134   G4double edel  = 0.5*e*(1.0 + x0*x0 - 4.0*x1*x1) - massPi0;
00135 
00136   do {
00137     // pi0 sample
00138     e0 = edel*G4UniformRand() + massPi0;
00139     p0 = sqrt(e0 - massPi0*massPi0);
00140     dir0 = G4RandomDirection();
00141     w0 = G4LorentzVector(p0*dir0.x(),p0*dir0.y(),p0*dir0.z(),e0);
00142 
00143     // pi+pi- pair
00144     w1 = G4LorentzVector(-p0*dir0.x(),-p0*dir0.y(),-p0*dir0.z(),e-e0);
00145     G4ThreeVector bst = w1.boostVector();
00146     e2 = 0.25*w1.m2();
00147 
00148     // pi+ 
00149     p = sqrt(e2 - massPi*massPi);
00150     dir1 = G4RandomDirection();
00151     w2 = G4LorentzVector(p*dir1.x(),p*dir1.y(),p*dir1.z(),sqrt(e2));
00152     w2.boost(bst);
00153     G4double px2 = w2.x();
00154     G4double py2 = w2.y();
00155     G4double pz2 = w2.z();
00156 
00157     // pi- 
00158     w1 -= w2;
00159     G4double px1 = w1.x();
00160     G4double py1 = w1.y();
00161     G4double pz1 = w1.z();
00162 
00163     m01 = w0*w1;
00164     m02 = w0*w2;
00165     m12 = w1*w2;
00166 
00167     G4double px = py1*pz2 - py2*pz1;
00168     G4double py = pz1*px2 - pz2*px1;
00169     G4double pz = px1*py2 - px2*py1;
00170 
00171     gg = (px*px + py*py + pz*pz)*
00172       norm( 1.0/cross->DpRho(m01) +  1.0/cross->DpRho(m02)
00173             + 1.0/cross->DpRho(m12) );
00174     if(gg > gmax) {
00175       G4cout << "G4eeTo3PiModel::SampleSecondaries WARNING matrix element g= "
00176              << gg << " > " << gmax << " (majoranta)" << G4endl;
00177     }
00178     if(gg > gcash) gcash = gg;
00179     
00180   } while( gmax*G4UniformRand() > gg );
00181 
00182   w0.rotateUz(direction);
00183   w1.rotateUz(direction);
00184   w2.rotateUz(direction);
00185 
00186   // create G4DynamicParticle objects 
00187   G4DynamicParticle* dp0 = 
00188      new G4DynamicParticle(G4PionZero::PionZero(), w0);
00189   G4DynamicParticle* dp1 = 
00190      new G4DynamicParticle(G4PionPlus::PionPlus(), w1);
00191   G4DynamicParticle* dp2 = 
00192      new G4DynamicParticle(G4PionMinus::PionMinus(), w2);
00193   newp->push_back(dp0);
00194   newp->push_back(dp1);
00195   newp->push_back(dp2);
00196 }

G4double G4eeTo3PiModel::ThresholdEnergy (  )  const [virtual]

Implements G4Vee2hadrons.

Definition at line 84 of file G4eeTo3PiModel.cc.

References G4Vee2hadrons::LowEnergy().

Referenced by PhysicsVector(), and SampleSecondaries().

00085 {
00086   return std::max(LowEnergy(),2.0*massPi + massPi0);
00087 }


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