G4FermiPhaseSpaceDecay Class Reference

#include <G4FermiPhaseSpaceDecay.hh>

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Public Member Functions
	G4FermiPhaseSpaceDecay ()
	~G4FermiPhaseSpaceDecay ()
std::vector< G4LorentzVector * > *	Decay (G4double parent_mass, const std::vector< G4double > &fragment_masses) const

Private Member Functions
G4double	PtwoBody (G4double E, G4double P1, G4double P2) const
G4ThreeVector	IsotropicVector (G4double Magnitude, CLHEP::HepRandomEngine *) const
G4double	BetaKopylov (G4int, CLHEP::HepRandomEngine *) const
std::vector< G4LorentzVector * > *	KopylovNBodyDecay (G4double, const std::vector< G4double > &) const
void	DumpProblem (G4double E, G4double P1, G4double P2, G4double P) const
	G4FermiPhaseSpaceDecay (const G4FermiPhaseSpaceDecay &)
const G4FermiPhaseSpaceDecay &	operator= (const G4FermiPhaseSpaceDecay &)
G4bool	operator== (const G4FermiPhaseSpaceDecay &)
G4bool	operator!= (const G4FermiPhaseSpaceDecay &)

Private Attributes
G4Pow *	g4pow

Detailed Description

Definition at line 51 of file G4FermiPhaseSpaceDecay.hh.

Constructor & Destructor Documentation

G4FermiPhaseSpaceDecay() [1/2]

G4FermiPhaseSpaceDecay::G4FermiPhaseSpaceDecay

(

)

Definition at line 42 of file G4FermiPhaseSpaceDecay.cc.

{
  g4pow = G4Pow::GetInstance();
}

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~G4FermiPhaseSpaceDecay()

G4FermiPhaseSpaceDecay::~G4FermiPhaseSpaceDecay

(

)

Definition at line 47 of file G4FermiPhaseSpaceDecay.cc.

{}

G4FermiPhaseSpaceDecay() [2/2]

G4FermiPhaseSpaceDecay::G4FermiPhaseSpaceDecay ( const G4FermiPhaseSpaceDecay &  )

private

Member Function Documentation

BetaKopylov()

G4double G4FermiPhaseSpaceDecay::BetaKopylov ( G4int  K, CLHEP::HepRandomEngine *  rndmEngine  ) const

inlineprivate

Definition at line 102 of file G4FermiPhaseSpaceDecay.hh.

{
  G4int N = 3*K - 5;
  G4double xN = G4double(N);
  G4double F;
  // VI variant
  G4double Fmax = std::sqrt(g4pow->powN(xN/(xN + 1),N)/(xN + 1)); 
  G4double chi;
  do {
    chi = rndmEngine->flat();
    F = std::sqrt(g4pow->powN(chi,N)*(1-chi));      
    // Loop checking, 05-Aug-2015, Vladimir Ivanchenko
   } while ( Fmax*rndmEngine->flat() > F);  
  return chi;
}

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Decay()

std::vector< G4LorentzVector * > * G4FermiPhaseSpaceDecay::Decay ( G4double  parent_mass, const std::vector< G4double > &  fragment_masses  ) const

inline

Definition at line 95 of file G4FermiPhaseSpaceDecay.hh.

{
  return KopylovNBodyDecay(parent_mass, fragment_masses);
}

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DumpProblem()

void G4FermiPhaseSpaceDecay::DumpProblem ( G4double  E, G4double  P1, G4double  P2, G4double  P  ) const

private

Definition at line 109 of file G4FermiPhaseSpaceDecay.cc.

{
  G4cout << "G4FermiPhaseSpaceDecay:  problem of decay of M(GeV)= " << E/GeV 
     << " on M1(GeV)= " << P1/GeV << " and  M2(GeV)= " << P2/GeV
     << " P(MeV)= " << P/MeV << " < 0" << G4endl;
  // exception only if the problem is numerically significant
  if(P < -CLHEP::eV) {
    throw G4HadronicException(__FILE__, __LINE__,"Error in decay kinematics");
  }
}

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IsotropicVector()

G4ThreeVector G4FermiPhaseSpaceDecay::IsotropicVector ( G4double  Magnitude, CLHEP::HepRandomEngine *  rndmEngine  ) const

inlineprivate

Definition at line 120 of file G4FermiPhaseSpaceDecay.hh.

{
  G4double CosTheta = 2.0*rndmEngine->flat() - 1.0;
  G4double SinTheta = std::sqrt((1. - CosTheta)*(1. + CosTheta));
  G4double Phi = CLHEP::twopi*rndmEngine->flat();
  G4ThreeVector Vector(Magnitude*std::cos(Phi)*SinTheta,
               Magnitude*std::sin(Phi)*SinTheta,
               Magnitude*CosTheta);
  return Vector;
}

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KopylovNBodyDecay()

std::vector< G4LorentzVector * > * G4FermiPhaseSpaceDecay::KopylovNBodyDecay ( G4double  M, const std::vector< G4double > &  mr  ) const

private

Definition at line 51 of file G4FermiPhaseSpaceDecay.cc.

{
  size_t N = mr.size();

  std::vector<G4LorentzVector*>* P = 
    new std::vector<G4LorentzVector*>(N, 0);

  G4double mtot = 0.0;
  for(size_t k=0; k<N; ++k) { mtot += mr[k]; }
  G4double mu = mtot;
  G4double PFragMagCM = 0.0;
  G4double Mass = M;
  G4double T = Mass-mtot;
  G4LorentzVector PFragCM(0.0,0.0,0.0,0.0);
  G4LorentzVector PRestCM(0.0,0.0,0.0,0.0);
  G4LorentzVector PRestLab(0.0,0.0,0.0,Mass);

  CLHEP::HepRandomEngine* rndmEngine = G4Random::getTheEngine();

  for (size_t k = N-1; k>0; --k)
    {
      mu -= mr[k];
      if (k>1) { T *= BetaKopylov(k, rndmEngine); }
      else     { T = 0.0; }
      
      G4double RestMass = mu + T;

      PFragMagCM = PtwoBody(Mass,mr[k],RestMass);
      
      // Create a unit vector with a random direction isotropically distributed
      G4ThreeVector RandVector(IsotropicVector(PFragMagCM, rndmEngine));

      PFragCM.setVect(RandVector);
      PFragCM.setE(std::sqrt(PFragMagCM*PFragMagCM + mr[k]*mr[k]));

      PRestCM.setVect(-RandVector);
      PRestCM.setE(std::sqrt(PFragMagCM*PFragMagCM + RestMass*RestMass));


      G4ThreeVector BoostV = PRestLab.boostVector();

      PFragCM.boost(BoostV);
      PRestCM.boost(BoostV);
      PRestLab = PRestCM;

      (*P)[k] = new G4LorentzVector(PFragCM);
      
      Mass = RestMass;
    }

  (*P)[0] = new G4LorentzVector(PRestLab);

  return P;
}

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operator!=()

G4bool G4FermiPhaseSpaceDecay::operator!= ( const G4FermiPhaseSpaceDecay &  )

private

operator=()

const G4FermiPhaseSpaceDecay& G4FermiPhaseSpaceDecay::operator= ( const G4FermiPhaseSpaceDecay &  )

private

operator==()

G4bool G4FermiPhaseSpaceDecay::operator== ( const G4FermiPhaseSpaceDecay &  )

private

PtwoBody()

G4double G4FermiPhaseSpaceDecay::PtwoBody ( G4double  E, G4double  P1, G4double  P2  ) const

inlineprivate

Definition at line 85 of file G4FermiPhaseSpaceDecay.hh.

{
  G4double res = 0.0;
  G4double P = (E+P1+P2)*(E+P1-P2)*(E-P1+P2)*(E-P1-P2)/(4.0*E*E);
  if (P>0.0) { res = std::sqrt(P); }
  else { DumpProblem(E,P1,P2,P); }
  return res;
}

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Member Data Documentation

g4pow

G4Pow* G4FermiPhaseSpaceDecay::g4pow

private

Definition at line 81 of file G4FermiPhaseSpaceDecay.hh.

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

• G4FermiPhaseSpaceDecay.hh
• G4FermiPhaseSpaceDecay.cc