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G4INCLPhaseSpaceKopylov.cc
Go to the documentation of this file. Or view the newest version in sPHENIX GitHub for file G4INCLPhaseSpaceKopylov.cc
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25 //
26 // INCL++ intra-nuclear cascade model
27 // Alain Boudard, CEA-Saclay, France
28 // Joseph Cugnon, University of Liege, Belgium
29 // Jean-Christophe David, CEA-Saclay, France
30 // Pekka Kaitaniemi, CEA-Saclay, France, and Helsinki Institute of Physics, Finland
31 // Sylvie Leray, CEA-Saclay, France
32 // Davide Mancusi, CEA-Saclay, France
33 //
34 #define INCLXX_IN_GEANT4_MODE 1
35 
36 #include "globals.hh"
37 
39 #include "G4INCLRandom.hh"
40 #include "G4INCLKinematicsUtils.hh"
41 #include <algorithm>
42 #include <numeric>
43 #include <functional>
44 
45 namespace G4INCL {
46 
48  G4int N = 3*K - 5;
49  G4double xN = G4double(N);
50  G4double Fmax = std::sqrt(std::pow(xN/(xN+1.),N)/(xN+1.));
51 
52  G4double F, chi;
53  unsigned long loopCounter = 0;
54  const unsigned long maxLoopCounter = 10000000;
55  do {
56  chi = Random::shoot();
57  F = std::sqrt(std::pow(chi,N)*(1.-chi));
58  ++loopCounter;
59  } while (loopCounter<maxLoopCounter && Fmax*Random::shoot() > F); /* Loop checking, 10.07.2015, D.Mancusi */
60  return chi;
61  }
62 
63  void PhaseSpaceKopylov::generate(const G4double sqrtS, ParticleList &particles) {
64 
65  boostV.setX(0.0);
66  boostV.setY(0.0);
67  boostV.setZ(0.0);
68 
69  const size_t N = particles.size();
70  masses.resize(N);
71  sumMasses.resize(N);
72  std::transform(particles.begin(), particles.end(), masses.begin(), std::mem_fn(&Particle::getMass));
73  std::partial_sum(masses.begin(), masses.end(), sumMasses.begin());
74 
75  G4double PFragMagCM = 0.0;
76  G4double T = sqrtS-sumMasses.back();
77 // assert(T>-1.e-5);
78  if(T<0.)
79  T=0.;
80 
81  // The first particle in the list will pick up all the recoil
82  Particle *restParticle = particles.front();
83  restParticle->setMass(sqrtS);
84  restParticle->adjustEnergyFromMomentum();
85 
86  G4int k=N-1;
87  for (ParticleList::reverse_iterator p=particles.rbegin(); k>0; ++p, --k) {
88  const G4double mu = sumMasses[k-1];
89  T *= (k>1) ? betaKopylov(k) : 0.;
90 
91  const G4double restMass = mu + T;
92 
93  PFragMagCM = KinematicsUtils::momentumInCM(restParticle->getMass(), masses[k], restMass);
94  PFragCM = Random::normVector(PFragMagCM);
95  (*p)->setMomentum(PFragCM);
96  (*p)->adjustEnergyFromMomentum();
97  restParticle->setMass(restMass);
98  restParticle->setMomentum(-PFragCM);
99  restParticle->adjustEnergyFromMomentum();
100 
101  (*p)->boost(boostV);
102  restParticle->boost(boostV);
103 
104  boostV = -restParticle->boostVector();
105  }
106  restParticle->setMass(masses[0]);
107  restParticle->adjustEnergyFromMomentum();
108  }
109 
110 }