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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 "G4INCLPiNElasticChannel.hh"
39 #include "G4INCLKinematicsUtils.hh"
40 #include "G4INCLBinaryCollisionAvatar.hh"
41 #include "G4INCLRandom.hh"
42 #include "G4INCLGlobals.hh"
43 #include "G4INCLLogger.hh"
44
45 namespace G4INCL {
46
47 PiNElasticChannel::PiNElasticChannel(Particle *p1, Particle *p2)
48 : particle1(p1), particle2(p2)
49 {
50
51 }
52
53 PiNElasticChannel::~PiNElasticChannel(){
54
55 }
56
57 void PiNElasticChannel::fillFinalState(FinalState *fs) {
58 Particle * nucleon;
59 Particle * pion;
60 if(particle1->isNucleon()) {
61 nucleon = particle1;
62 pion = particle2;
63 } else {
64 nucleon = particle2;
65 pion = particle1;
66 }
67
68 G4double bpn=8e-6; // B-parameter of exp(Bt) - (MeV/c)^-2
69 G4double px_nucleon=nucleon->getMomentum().getX();
70 G4double py_nucleon=nucleon->getMomentum().getY();
71 G4double pz_nucleon=nucleon->getMomentum().getZ();
72 G4double cnorm1=px_nucleon*px_nucleon+py_nucleon*py_nucleon;
73 G4double cnorm2=std::sqrt(cnorm1);
74 G4double tnorm=cnorm1+pz_nucleon*pz_nucleon;
75 G4double cnorm=std::sqrt(tnorm);
76 G4double btm=std::exp(-4.*tnorm*bpn);
77 G4double rndm=Random::shoot();
78 G4double yrn=1.-rndm*(1.-btm);
79 G4double tt=std::log(yrn)/bpn;
80 G4double ctheta=1.+0.5*tt/tnorm;
81 G4double stheta=std::sqrt(1.-ctheta*ctheta);
82 G4double t7=1.-2.*Random::shoot();
83 G4double t8=std::sqrt(1-t7*t7);
84 G4double t1=-py_nucleon/cnorm2;
85 G4double t2=px_nucleon/cnorm2;
86 G4double t4=t2*pz_nucleon/cnorm;
87 G4double t5=-t1*pz_nucleon/cnorm;
88 G4double t6=-cnorm2/cnorm;
89 ThreeVector mom_nucleon(
90 px_nucleon*ctheta+cnorm*stheta*(t1*t7+t4*t8),
91 py_nucleon*ctheta+cnorm*stheta*(t2*t7+t5*t8),
92 pz_nucleon*ctheta+cnorm*stheta*t6*t8
93 );
94 nucleon->setMomentum(mom_nucleon);
95 pion->setMomentum(-mom_nucleon);
96
97 #ifdef INCLXX_IN_GEANT4_MODE
98 ParticleType startingNucleonType = nucleon->getType();
99 ParticleType startingPionType = pion->getType();
100 #endif
101
102 G4int iso=ParticleTable::getIsospin(nucleon->getType())+ParticleTable::getIsospin(pion->getType());
103 if (iso == 1 || iso == -1) {
104 rndm=3*Random::shoot();
105 if (rndm < 1.) {
106 ParticleType nucleonType=ParticleTable::getNucleonType(-iso);
107 nucleon->setType(nucleonType);
108 ParticleType pionType=ParticleTable::getPionType(2*iso);
109 pion->setType(pionType);
110 }
111 else {
112 ParticleType nucleonType=ParticleTable::getNucleonType(iso);
113 nucleon->setType(nucleonType);
114 pion->setType(PiZero);
115 }
116 }
117 else { // Useless
118 ParticleType nucleonType=ParticleTable::getNucleonType(iso/3);
119 nucleon->setType(nucleonType);
120 ParticleType pionType=ParticleTable::getPionType(2*iso/3);
121 pion->setType(pionType);
122 }
123
124 #ifdef INCLXX_IN_GEANT4_MODE
125 // Erase the parent resonance information if the nucleon or pion changes type
126 if ( startingNucleonType != nucleon->getType() || startingPionType != pion->getType() ) {
127 nucleon->setParentResonancePDGCode(0);
128 nucleon->setParentResonanceID(0);
129 pion->setParentResonancePDGCode(0);
130 pion->setParentResonanceID(0);
131 }
132 #endif
133
134 fs->addModifiedParticle(nucleon);
135 fs->addModifiedParticle(pion);
136 }
137
138 }
139