source: trunk/source/processes/electromagnetic/standard/src/G4CoulombScatteringModel.cc @ 1055

Last change on this file since 1055 was 1055, checked in by garnier, 15 years ago

maj sur la beta de geant 4.9.3
File size: 6.7 KB
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26// $Id: G4CoulombScatteringModel.cc,v 1.39 2009/05/10 16:09:29 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-03-beta-cand-01 $
28//
29// -------------------------------------------------------------------
30//
31// GEANT4 Class file
32//
33//
34// File name:     G4CoulombScatteringModel
35//
36// Author:        Vladimir Ivanchenko
37//
38// Creation date: 22.08.2005
39//
40// Modifications:
41// 01.08.06 V.Ivanchenko extend upper limit of table to TeV and review the
42//          logic of building - only elements from G4ElementTable
43// 08.08.06 V.Ivanchenko build internal table in ekin scale, introduce faclim
44// 19.10.06 V.Ivanchenko use inheritance from G4eCoulombScatteringModel
45// 09.10.07 V.Ivanchenko reorganized methods, add cut dependence in scattering off e-
46// 09.06.08 V.Ivanchenko SelectIsotope is moved to the base class
47//
48// Class Description:
49//
50// -------------------------------------------------------------------
51//
52//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
53//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
54
55#include "G4CoulombScatteringModel.hh"
56#include "Randomize.hh"
57#include "G4ParticleChangeForGamma.hh"
58#include "G4ParticleTable.hh"
59#include "G4IonTable.hh"
60#include "G4Proton.hh"
61
62//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
63
64using namespace std;
65
66G4CoulombScatteringModel::G4CoulombScatteringModel(const G4String& nam)
67  : G4eCoulombScatteringModel(nam)
68{}
69
70//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
71
72G4CoulombScatteringModel::~G4CoulombScatteringModel()
73{}
74
75//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
76
77G4double G4CoulombScatteringModel::ComputeCrossSectionPerAtom(
78                                const G4ParticleDefinition* p,
79                                G4double kinEnergy, 
80                                G4double Z, 
81                                G4double, 
82                                G4double cutEnergy,
83                                G4double)
84{
85  SetupParticle(p);
86  G4double ekin = std::max(lowEnergyLimit, kinEnergy);
87  SetupKinematic(ekin, cutEnergy);
88
89  // save lab system kinematics
90  G4double xtkin = tkin;
91  G4double xmom2 = mom2;
92  G4double xinvb = invbeta2;
93
94  // CM system
95  iz            = G4int(Z);
96  G4double m2   = fNistManager->GetAtomicMassAmu(iz)*amu_c2;
97  G4double etot = tkin + mass;
98  G4double ptot = sqrt(mom2);
99
100  G4double m12  = mass*mass;
101  G4double momCM= ptot*m2/sqrt(m12 + m2*m2 + 2.0*etot*m2);
102
103  mom2 = momCM*momCM;
104  tkin = sqrt(mom2 + m12) - mass;
105  invbeta2 = 1.0 +  m12/mom2;
106
107  SetupTarget(Z, tkin);
108
109  G4double xsec = CrossSectionPerAtom();
110
111  // restore Lab system kinematics
112  tkin = xtkin;
113  mom2 = xmom2;
114  invbeta2 = xinvb;
115
116  return xsec;
117}
118
119//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
120
121void G4CoulombScatteringModel::SampleSecondaries(
122                               std::vector<G4DynamicParticle*>* fvect,
123                               const G4MaterialCutsCouple* couple,
124                               const G4DynamicParticle* dp,
125                               G4double cutEnergy, 
126                               G4double)
127{
128  G4double kinEnergy = dp->GetKineticEnergy();
129  if(kinEnergy <= DBL_MIN) return;
130  DefineMaterial(couple);
131  SetupParticle(dp->GetDefinition());
132  G4double ekin = std::max(lowEnergyLimit, kinEnergy);
133  SetupKinematic(ekin, cutEnergy);
134
135  // Choose nucleus
136  currentElement = SelectRandomAtom(couple,particle,ekin,ecut,tkin);
137
138  G4double Z  = currentElement->GetZ();
139  iz          = G4int(Z);
140  G4int ia    = SelectIsotopeNumber(currentElement);
141  G4double m2 = theParticleTable->GetIonTable()->GetNucleusMass(iz, ia);
142
143  // CM system
144  G4double etot = tkin + mass;
145  G4double ptot = sqrt(mom2);
146
147  G4double momCM= ptot*m2/sqrt(mass*mass + m2*m2 + 2.0*etot*m2);
148  mom2 = momCM*momCM;
149  G4double m12 = mass*mass;
150  G4double eCM = sqrt(mom2 + m12);
151
152  // a correction for heavy projectile
153  G4double fm = m2/(mass + m2);
154  invbeta2 = 1.0 +  m12*fm*fm/mom2;
155
156  // sample scattering angle in CM system
157  SetupTarget(Z, eCM - mass);
158
159  G4double cost = SampleCosineTheta();
160  G4double z1   = 1.0 - cost;
161  if(z1 < 0.0) return;
162
163  G4double sint = sqrt(z1*(1.0 + cost));
164  G4double phi  = twopi * G4UniformRand();
165
166  // kinematics in the Lab system
167  G4double bet  = ptot/(etot + m2);
168  G4double gam  = 1.0/sqrt((1.0 - bet)*(1.0 + bet));
169  G4double pzCM = momCM*cost;
170
171  G4ThreeVector v1(momCM*cos(phi)*sint,momCM*sin(phi)*sint,gam*(pzCM + bet*eCM));
172  G4ThreeVector dir = dp->GetMomentumDirection(); 
173  G4ThreeVector newDirection = v1.unit();
174  newDirection.rotateUz(dir);   
175  fParticleChange->ProposeMomentumDirection(newDirection);   
176
177  G4double elab = gam*(eCM + bet*pzCM);
178  ekin = elab - mass;
179  if(ekin < 0.0) ekin = 0.0;
180  fParticleChange->SetProposedKineticEnergy(ekin);
181
182  // recoil
183  G4double erec = kinEnergy - ekin;
184
185  if(erec > recoilThreshold) {
186    G4ParticleDefinition* ion = theParticleTable->FindIon(iz, ia, 0, iz);
187    G4double plab = sqrt(ekin*(ekin + 2.0*mass));
188    G4ThreeVector p2 = (ptot*dir - plab*newDirection).unit();
189    G4DynamicParticle* newdp  = new G4DynamicParticle(ion, p2, erec);
190    fvect->push_back(newdp);
191  } else if(erec > 0.0) {
192    fParticleChange->ProposeLocalEnergyDeposit(erec);
193    fParticleChange->ProposeNonIonizingEnergyDeposit(erec);
194  }
195}
196
197//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
198
199
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