G4INCL::PhaseSpaceKopylov Class Reference

Generate momenta using the Kopylov method. More...

#include <G4INCLPhaseSpaceKopylov.hh>

Inheritance diagram for G4INCL::PhaseSpaceKopylov:

Public Member Functions
void	generate (const G4double sqrtS, ParticleList &particles)
	Generate momenta according to a uniform, non-Lorentz-invariant phase-space model. More...

Private Member Functions
G4double	betaKopylov (G4int K) const
	Internal function used by the Kopylov algorithm. More...

Private Attributes
ThreeVector	boostV
std::vector< G4double >	masses
ThreeVector	PFragCM
ThreeVector	PRestCM
std::vector< G4double >	sumMasses

Detailed Description

Generate momenta using the Kopylov method.

Definition at line 48 of file G4INCLPhaseSpaceKopylov.hh.

Member Function Documentation

betaKopylov()

G4double G4INCL::PhaseSpaceKopylov::betaKopylov ( G4int  K ) const

private

Internal function used by the Kopylov algorithm.

Definition at line 47 of file G4INCLPhaseSpaceKopylov.cc.

                                                       {
    G4int N = 3*K - 5;
    G4double xN = G4double(N);
    G4double Fmax = std::sqrt(std::pow(xN/(xN+1.),N)/(xN+1.));
 
    G4double F, chi;
    unsigned long loopCounter = 0;
    const unsigned long maxLoopCounter = 10000000;
    do {
      chi = Random::shoot();
      F = std::sqrt(std::pow(chi,N)*(1.-chi));
      ++loopCounter;
    } while (loopCounter<maxLoopCounter && Fmax*Random::shoot() > F); /* Loop checking, 10.07.2015, D.Mancusi */
    return chi;
  }

References G4INCL::Random::shoot().

Referenced by generate().

generate()

void G4INCL::PhaseSpaceKopylov::generate ( const G4double  sqrtS, ParticleList &  particles  )

virtual

Generate momenta according to a uniform, non-Lorentz-invariant phase-space model.

This function will assign momenta to the particles in the list that is passed as an argument. The event is generated in the CM frame.

Parameters

sqrtS	total centre-of-mass energy of the system
particles	list of particles

Implements G4INCL::IPhaseSpaceGenerator.

Definition at line 63 of file G4INCLPhaseSpaceKopylov.cc.

                                                                                {
 
    boostV.setX(0.0);
    boostV.setY(0.0);
    boostV.setZ(0.0);
 
    const size_t N = particles.size();
    masses.resize(N);
    sumMasses.resize(N);
    std::transform(particles.begin(), particles.end(), masses.begin(), std::mem_fn(&Particle::getMass));
    std::partial_sum(masses.begin(), masses.end(), sumMasses.begin());
 
    G4double PFragMagCM = 0.0;
    G4double T = sqrtS-sumMasses.back();
// assert(T>-1.e-5);
    if(T<0.)
      T=0.;
 
    // The first particle in the list will pick up all the recoil
    Particle *restParticle = particles.front();
    restParticle->setMass(sqrtS);
    restParticle->adjustEnergyFromMomentum();
 
    G4int k=N-1;
    for (ParticleList::reverse_iterator p=particles.rbegin(); k>0; ++p, --k) {
      const G4double mu = sumMasses[k-1];
      T *= (k>1) ? betaKopylov(k) : 0.;
 
      const G4double restMass = mu + T;
 
      PFragMagCM = KinematicsUtils::momentumInCM(restParticle->getMass(), masses[k], restMass);
      PFragCM = Random::normVector(PFragMagCM);
      (*p)->setMomentum(PFragCM);
      (*p)->adjustEnergyFromMomentum();
      restParticle->setMass(restMass);
      restParticle->setMomentum(-PFragCM);
      restParticle->adjustEnergyFromMomentum();
 
      (*p)->boost(boostV);
      restParticle->boost(boostV);
 
      boostV = -restParticle->boostVector();
    }
    restParticle->setMass(masses[0]);
    restParticle->adjustEnergyFromMomentum();
  }

References G4INCL::Particle::adjustEnergyFromMomentum(), betaKopylov(), G4INCL::Particle::boost(), boostV, G4INCL::Particle::boostVector(), G4INCL::Particle::getMass(), masses, G4INCL::KinematicsUtils::momentumInCM(), G4INCL::Random::normVector(), PFragCM, G4INCL::Particle::setMass(), G4INCL::Particle::setMomentum(), G4INCL::ThreeVector::setX(), G4INCL::ThreeVector::setY(), G4INCL::ThreeVector::setZ(), sumMasses, and G4coutFormatters::anonymous_namespace{G4coutFormatters.cc}::transform().

Field Documentation

boostV

ThreeVector G4INCL::PhaseSpaceKopylov::boostV

private

Definition at line 68 of file G4INCLPhaseSpaceKopylov.hh.

Referenced by generate().

masses

std::vector<G4double> G4INCL::PhaseSpaceKopylov::masses

private

Definition at line 65 of file G4INCLPhaseSpaceKopylov.hh.

Referenced by generate().

PFragCM

ThreeVector G4INCL::PhaseSpaceKopylov::PFragCM

private

Definition at line 67 of file G4INCLPhaseSpaceKopylov.hh.

Referenced by generate().

PRestCM

ThreeVector G4INCL::PhaseSpaceKopylov::PRestCM

private

Definition at line 67 of file G4INCLPhaseSpaceKopylov.hh.

sumMasses

std::vector<G4double> G4INCL::PhaseSpaceKopylov::sumMasses

private

Definition at line 66 of file G4INCLPhaseSpaceKopylov.hh.

Referenced by generate().

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

• source/processes/hadronic/models/inclxx/incl_physics/include/G4INCLPhaseSpaceKopylov.hh
• source/processes/hadronic/models/inclxx/incl_physics/src/G4INCLPhaseSpaceKopylov.cc