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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
38 #include "G4INCLPhaseSpaceKopylov.hh"
39 #include "G4INCLRandom.hh"
40 #include "G4INCLKinematicsUtils.hh"
41 #include <algorithm>
42 #include <numeric>
43 #include <functional>
44
45 namespace G4INCL {
46
47 G4double PhaseSpaceKopylov::betaKopylov(G4int K) const {
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 std::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=G4int(N-1);
87 for (auto 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 }
111