Geant4 11.1.1
Toolkit for the simulation of the passage of particles through matter
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G4INCL::ElasticChannel Class Reference

#include <G4INCLElasticChannel.hh>

+ Inheritance diagram for G4INCL::ElasticChannel:

Public Member Functions

 ElasticChannel (Particle *p1, Particle *p2)
 
virtual ~ElasticChannel ()
 
void fillFinalState (FinalState *fs)
 
- Public Member Functions inherited from G4INCL::IChannel
 IChannel ()
 
virtual ~IChannel ()
 
FinalStategetFinalState ()
 
virtual void fillFinalState (FinalState *fs)=0
 

Detailed Description

Definition at line 49 of file G4INCLElasticChannel.hh.

Constructor & Destructor Documentation

◆ ElasticChannel()

G4INCL::ElasticChannel::ElasticChannel ( Particle p1,
Particle p2 
)

Definition at line 47 of file G4INCLElasticChannel.cc.

48 :particle1(p1), particle2(p2)
49 {
50 }

◆ ~ElasticChannel()

G4INCL::ElasticChannel::~ElasticChannel ( )
virtual

Definition at line 52 of file G4INCLElasticChannel.cc.

53 {
54 }

Member Function Documentation

◆ fillFinalState()

void G4INCL::ElasticChannel::fillFinalState ( FinalState fs)
virtual

Implements G4INCL::IChannel.

Definition at line 56 of file G4INCLElasticChannel.cc.

57 {
58 ParticleType p1TypeOld = particle1->getType();
59 ParticleType p2TypeOld = particle2->getType();
60
61 /* Concerning the way we calculate the lab momentum, see the considerations
62 * in CrossSections::elasticNNLegacy().
63 */
64 const G4double s = KinematicsUtils::squareTotalEnergyInCM(particle1, particle2);
66
67 const G4int isospin = ParticleTable::getIsospin(particle1->getType()) +
69
70 // Calculate the outcome of the channel:
71 G4double psq = particle1->getMomentum().mag2();
72 G4double pnorm = std::sqrt(psq);
74 G4double btmax = 4.0 * psq * b;
75 G4double z = std::exp(-btmax);
76 G4double ranres = Random::shoot();
77 G4double y = 1.0 - ranres * (1.0 - z);
78 G4double T = std::log(y)/b;
79 G4int iexpi = 0;
80 G4double apt = 1.0;
81
82 // Handle np case
83 if((particle1->getType() == Proton && particle2->getType() == Neutron) ||
84 (particle1->getType() == Neutron && particle2->getType() == Proton)) {
85 if(pl > 800.0) {
86 const G4double x = 0.001 * pl; // Transform to GeV
87 apt = (800.0/pl)*(800.0/pl);
88 G4double cpt = std::max(6.23 * std::exp(-1.79*x), 0.3);
89 G4double alphac = 100.0 * 1.0e-6;
90 G4double aaa = (1 + apt) * (1 - std::exp(-btmax))/b;
91 G4double argu = psq * alphac;
92
93 if(argu >= 8) {
94 argu = 0.0;
95 } else {
96 argu = std::exp(-4.0 * argu);
97 }
98
99 G4double aac = cpt * (1.0 - argu)/alphac;
100 G4double fracpn = aaa/(aac + aaa);
101 if(Random::shoot() > fracpn) {
102 z = std::exp(-4.0 * psq *alphac);
103 iexpi = 1;
104 y = 1.0 - ranres*(1.0 - z);
105 T = std::log(y)/alphac;
106 }
107 }
108 }
109
110 G4double ctet = 1.0 + 0.5*T/psq;
111 if(std::abs(ctet) > 1.0) ctet = Math::sign(ctet);
112 G4double stet = std::sqrt(1.0 - ctet*ctet);
113 G4double rndm = Random::shoot();
114
115 G4double fi = Math::twoPi * rndm;
116 G4double cfi = std::cos(fi);
117 G4double sfi = std::sin(fi);
118
119 G4double xx = particle1->getMomentum().perp2();
120 G4double zz = std::pow(particle1->getMomentum().getZ(), 2);
121
122 if(xx >= (zz * 1.0e-8)) {
123 ThreeVector p = particle1->getMomentum();
124 G4double yn = std::sqrt(xx);
125 G4double zn = yn * pnorm;
126 G4double ex[3], ey[3], ez[3];
127 ez[0] = p.getX() / pnorm;
128 ez[1] = p.getY() / pnorm;
129 ez[2] = p.getZ() / pnorm;
130
131 // Vector Ex is chosen arbitrarily:
132 ex[0] = p.getY() / yn;
133 ex[1] = -p.getX() / yn;
134 ex[2] = 0.0;
135
136 ey[0] = p.getX() * p.getZ() / zn;
137 ey[1] = p.getY() * p.getZ() / zn;
138 ey[2] = -xx/zn;
139
140 G4double pX = (ex[0]*cfi*stet + ey[0]*sfi*stet + ez[0]*ctet) * pnorm;
141 G4double pY = (ex[1]*cfi*stet + ey[1]*sfi*stet + ez[1]*ctet) * pnorm;
142 G4double pZ = (ex[2]*cfi*stet + ey[2]*sfi*stet + ez[2]*ctet) * pnorm;
143
144 ThreeVector p1momentum = ThreeVector(pX, pY, pZ);
145 particle1->setMomentum(p1momentum);
146 particle2->setMomentum(-p1momentum);
147 } else { // if(xx < (zz * 1.0e-8)) {
148 G4double momZ = particle1->getMomentum().getZ();
149 G4double pX = momZ * cfi * stet;
150 G4double pY = momZ * sfi * stet;
151 G4double pZ = momZ * ctet;
152
153 ThreeVector p1momentum(pX, pY, pZ);
154 particle1->setMomentum(p1momentum);
155 particle2->setMomentum(-p1momentum);
156 }
157
158 // Handle backward scattering here.
159
160 if((particle1->getType() == Proton && particle2->getType() == Neutron) ||
161 (particle1->getType() == Neutron && particle2->getType() == Proton)) {
162 rndm = Random::shoot();
163 apt = 1.0;
164 if(pl > 800.0) {
165 apt = std::pow(800.0/pl, 2);
166 }
167 if(iexpi == 1 || rndm > 1.0/(1.0 + apt)) {
168 particle1->setType(p2TypeOld);
169 particle2->setType(p1TypeOld);
170 }
171 }
172
173 // Note: there is no need to update the kinetic energies of the particles,
174 // as this is elastic scattering.
175
176 fs->addModifiedParticle(particle1);
177 fs->addModifiedParticle(particle2);
178
179 }
double G4double
Definition: G4Types.hh:83
int G4int
Definition: G4Types.hh:85
const G4INCL::ThreeVector & getMomentum() const
virtual void setMomentum(const G4INCL::ThreeVector &momentum)
G4INCL::ParticleType getType() const
void setType(ParticleType t)
G4double getZ() const
G4double perp2() const
G4double mag2() const
G4double calculateNNAngularSlope(G4double energyCM, G4int iso)
Calculate the slope of the NN DDXS.
G4double squareTotalEnergyInCM(Particle const *const p1, Particle const *const p2)
G4double momentumInLab(Particle const *const p1, Particle const *const p2)
gives the momentum in the lab frame of two particles.
const G4double twoPi
G4int sign(const T t)
G4int getIsospin(const ParticleType t)
Get the isospin of a particle.
const G4double effectiveNucleonMass
G4double shoot()
Definition: G4INCLRandom.cc:93

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