Geant4-11
Public Member Functions | Private Member Functions | Private Attributes
G4INCL::PiNToEtaChannel Class Reference

#include <G4INCLPiNToEtaChannel.hh>

Inheritance diagram for G4INCL::PiNToEtaChannel:
G4INCL::IChannel

Public Member Functions

void fillFinalState (FinalState *fs)
 
FinalState * getFinalState ()
 
 PiNToEtaChannel (Particle *, Particle *)
 
virtual ~PiNToEtaChannel ()
 

Private Member Functions

 INCL_DECLARE_ALLOCATION_POOL (PiNToEtaChannel)
 

Private Attributes

Particle * particle1
 
Particle * particle2
 

Detailed Description

Definition at line 47 of file G4INCLPiNToEtaChannel.hh.

Constructor & Destructor Documentation

◆ PiNToEtaChannel()

G4INCL::PiNToEtaChannel::PiNToEtaChannel ( Particle *  p1,
Particle *  p2 
)

Definition at line 47 of file G4INCLPiNToEtaChannel.cc.

48 : particle1(p1), particle2(p2)
49 {
50
51 }

◆ ~PiNToEtaChannel()

G4INCL::PiNToEtaChannel::~PiNToEtaChannel ( )
virtual

Definition at line 53 of file G4INCLPiNToEtaChannel.cc.

53 {
54
55 }

Member Function Documentation

◆ fillFinalState()

void G4INCL::PiNToEtaChannel::fillFinalState ( FinalState *  fs)
virtual

Implements G4INCL::IChannel.

Definition at line 57 of file G4INCLPiNToEtaChannel.cc.

57 {
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
69 G4int iso=ParticleTable::getIsospin(nucleon->getType())+ParticleTable::getIsospin(pion->getType());
70// assert(iso == 1 || iso == -1);
71 if (iso == 1) {
72 nucleon->setType(Proton);
73 }
74 else if (iso == -1) {
75 nucleon->setType(Neutron);
76 }
77 pion->setType(Eta);
78 G4double sh=nucleon->getEnergy()+pion->getEnergy();
79 G4double mn=nucleon->getMass();
80 G4double me=pion->getMass();
81 G4double en=(sh*sh+mn*mn-me*me)/(2*sh);
82 nucleon->setEnergy(en);
83 G4double ee=std::sqrt(en*en-mn*mn+me*me);
84 pion->setEnergy(ee);
85 G4double pn=std::sqrt(en*en-mn*mn);
86
87// real distribution (from PRC 78, 025204 (2008))
88
89
90 G4double ECM=G4INCL::KinematicsUtils::totalEnergyInCM(particle1,particle2);
91
92 const G4double pi=std::acos(-1.0);
93 G4double x1;
94 G4double u1;
95 G4double fteta;
96 G4double teta;
97 G4double fi;
98
99 if (ECM < 1650.) {
100// below 1650 MeV - angular distribution (x=cos(theta): ax^2+bx+c
101
102 G4double f1= -0.0000288627*ECM*ECM+0.09155289*ECM-72.25436; // f(1) that is the maximum (fit on experimental data)
103 G4double b1=(f1-(f1/(1.5-0.5*std::pow((ECM-1580.)/95.,2))))/2.; // ideas: 1) f(-1)=0.5f(1); 2) "power term" flattens the distribution away from ECM=1580 MeV
104 G4double a1=2.5*b1; // minimum at cos(theta) = -0.2
105 G4double c1=f1-3.5*b1;
106
107 G4double interg1=2.*a1/3. +2.*c1; // (integral to normalize)
108
109 G4int passe1=0;
110 while (passe1==0) {
111 // Sample x from -1 to 1
112 x1=Random::shoot();
113 if (Random::shoot() > 0.5) x1=-x1;
114
115 // Sample u from 0 to 1
116 u1=Random::shoot();
117 fteta=(a1*x1*x1+b1*x1+c1)/interg1;
118 // The condition
119 if (u1*f1/interg1 < fteta) {
120 teta=std::acos(x1);
121 passe1=1;
122 }
123 }
124 }
125 else {
126// above 1650 MeV - angular distribution (x=cos(theta): (ax^2+bx+c)*(0.5+(arctan(10*(x+dev)))/pi) + vert
127
128 G4double a2=-0.29;
129 G4double b2=0.348; // ax^2+bx+c: around cos(theta)=0.6 with maximum at 0.644963 (value = 0.1872666)
130 G4double c2=0.0546;
131 G4double dev=-0.2; // tail close to zero from "dev" down to -1
132 G4double vert=0.04; // to avoid negative differential cross sections
133
134 G4double interg2=0.1716182902205207; // with the above given parameters! (integral to normalize)
135 const G4double f2=1.09118088; // maximum (integral taken into account)
136
137 G4int passe2=0;
138 while (passe2==0) {
139 // Sample x from -1 to 1
140 x1=Random::shoot();
141 if (Random::shoot() > 0.5) x1=-x1;
142
143 // Sample u from 0 to 1
144 u1=Random::shoot();
145 fteta=((a2*x1*x1+b2*x1+c2)*(0.5+(std::atan(10*(x1+dev)))/pi) + vert)/interg2;
146 // The condition
147 if (u1*f2 < fteta) {
148 teta=std::acos(x1);
149 passe2=1;
150 }
151 }
152 }
153
154 fi=(2.0*pi)*Random::shoot();
155
156 ThreeVector mom_nucleon(
157 pn*std::sin(teta)*std::cos(fi),
158 pn*std::sin(teta)*std::sin(fi),
159 pn*std::cos(teta)
160 );
161// end real distribution
162
163 nucleon->setMomentum(-mom_nucleon);
164 pion->setMomentum(mom_nucleon);
165
166 fs->addModifiedParticle(nucleon);
167 fs->addModifiedParticle(pion);
168 }
pi
static constexpr double pi
Definition: G4SIunits.hh:55
G4double
double G4double
Definition: G4Types.hh:83
G4int
int G4int
Definition: G4Types.hh:85
G4INCL::Particle::isNucleon
G4bool isNucleon() const
Definition: G4INCLParticle.hh:303
G4INCL::KinematicsUtils::totalEnergyInCM
G4double totalEnergyInCM(Particle const *const p1, Particle const *const p2)
Definition: G4INCLKinematicsUtils.cc:94
G4INCL::ParticleTable::getIsospin
G4int getIsospin(const ParticleType t)
Get the isospin of a particle.
Definition: G4INCLParticleTable.cc:478
G4INCL::Random::shoot
G4double shoot()
Definition: G4INCLRandom.cc:93
G4InuclParticleNames::pion
G4bool pion(G4int ityp)
Definition: G4InuclParticleNames.hh:90
G4InuclParticleNames::nucleon
G4bool nucleon(G4int ityp)
Definition: G4InuclParticleNames.hh:94

References G4INCL::FinalState::addModifiedParticle(), G4INCL::Eta, G4INCL::ParticleTable::getIsospin(), G4INCL::Particle::isNucleon(), G4INCL::Neutron, G4InuclParticleNames::nucleon(), particle1, particle2, pi, G4InuclParticleNames::pion(), G4InuclParticleNames::pn, G4INCL::Proton, G4INCL::Random::shoot(), and G4INCL::KinematicsUtils::totalEnergyInCM().

◆ getFinalState()

FinalState * G4INCL::IChannel::getFinalState ( )
inherited

Definition at line 50 of file G4INCLIChannel.cc.

50 {
51 FinalState *fs = new FinalState;
52 fillFinalState(fs);
53 return fs;
54 }
G4INCL::IChannel::fillFinalState
virtual void fillFinalState(FinalState *fs)=0

References G4INCL::IChannel::fillFinalState().

◆ INCL_DECLARE_ALLOCATION_POOL()

G4INCL::PiNToEtaChannel::INCL_DECLARE_ALLOCATION_POOL ( PiNToEtaChannel  )
private

Field Documentation

◆ particle1

Particle* G4INCL::PiNToEtaChannel::particle1
private

Definition at line 55 of file G4INCLPiNToEtaChannel.hh.

Referenced by fillFinalState().

◆ particle2

Particle * G4INCL::PiNToEtaChannel::particle2
private

Definition at line 55 of file G4INCLPiNToEtaChannel.hh.

Referenced by fillFinalState().

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