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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 "G4INCLSigmaZeroDecayChannel.hh"
39 #include "G4INCLKinematicsUtils.hh"
40 #include "G4INCLBinaryCollisionAvatar.hh"
41 #include "G4INCLRandom.hh"
42 #include "G4INCLGlobals.hh"
43
44 namespace G4INCL {
45
46 SigmaZeroDecayChannel::SigmaZeroDecayChannel(Particle *p, ThreeVector const &dir)
47 :theParticle(p), incidentDirection(dir)
48 {}
49
50 SigmaZeroDecayChannel::~SigmaZeroDecayChannel() {}
51
52
53 G4double SigmaZeroDecayChannel::computeDecayTime(Particle *p) {
54 // assert(p->getType() == SigmaZero);
55 const G4double gamma = std::sqrt(1+std::pow(p->getMomentum().mag()/p->getMass(),2));
56 const G4double tau = ParticleTable::getWidth(SigmaZero)*3E8*1E15*gamma; // fm
57 const G4double t = -tau * std::log(Random::shoot());
58 return t;
59 }
60
61 void SigmaZeroDecayChannel::sampleAngles(G4double *ctet_par, G4double *stet_par, G4double *phi_par) {
62
63 (*ctet_par) = -1.0 + 2.0*Random::shoot();
64 if(std::abs(*ctet_par) > 1.0) (*ctet_par) = Math::sign(*ctet_par); // needed?
65 (*stet_par) = std::sqrt(1.-(*ctet_par)*(*ctet_par));
66 (*phi_par) = Math::twoPi * Random::shoot();
67 }
68
69 void SigmaZeroDecayChannel::fillFinalState(FinalState *fs) {
70
71 // assert( theParticle->getType() == SigmaZero);
72 ParticleType createdType = Photon;
73
74 const G4double sqrtS = theParticle->getMass();
75
76 theParticle->setType(Lambda);
77 G4double phi, c_tet, s_tet;
78 sampleAngles(&c_tet, &s_tet, &phi);
79
80 G4double c_phi = std::cos(phi);
81 G4double s_phi = std::sin(phi);
82 G4double beta = incidentDirection.mag();
83
84 G4double q1, q2, q3;
85 G4double sal=0.0;
86 if (beta >= 1.0e-10)
87 sal = incidentDirection.perp()/beta;
88 if (sal >= 1.0e-6) {
89 G4double b1 = incidentDirection.getX();
90 G4double b2 = incidentDirection.getY();
91 G4double b3 = incidentDirection.getZ();
92 G4double cal = b3/beta;
93 G4double t1 = c_tet+cal*s_tet*s_phi/sal;
94 G4double t2 = s_tet/sal;
95 q1=(b1*t1+b2*t2*c_phi)/beta;
96 q2=(b2*t1-b1*t2*c_phi)/beta;
97 q3=(b3*t1/beta-t2*s_phi);
98 } else {
99 q1 = s_tet*c_phi;
100 q2 = s_tet*s_phi;
101 q3 = c_tet;
102 }
103
104 G4double xq = KinematicsUtils::momentumInCM(sqrtS,
105 theParticle->getMass(),
106 ParticleTable::getINCLMass(createdType));
107 q1 *= xq;
108 q2 *= xq;
109 q3 *= xq;
110
111 ThreeVector createdMomentum(q1, q2, q3);
112 ThreeVector createdPosition(theParticle->getPosition());
113 Particle *createdParticle = new Particle(createdType, createdMomentum, createdPosition);
114 theParticle->setMomentum(-createdMomentum);
115 theParticle->adjustEnergyFromMomentum();
116
117 fs->addModifiedParticle(theParticle);
118 fs->addCreatedParticle(createdParticle);
119
120 }
121 }
122