source: trunk/source/processes/electromagnetic/standard/src/G4CoulombScatteringModel.cc @ 1228

Last change on this file since 1228 was 1228, checked in by garnier, 14 years ago

update geant4.9.3 tag
File size: 7.3 KB
Line 
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26// $Id: G4CoulombScatteringModel.cc,v 1.44 2009/12/03 09:59:07 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-03 $
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//
42// 01.08.06 V.Ivanchenko extend upper limit of table to TeV and review the
43//          logic of building - only elements from G4ElementTable
44// 08.08.06 V.Ivanchenko build internal table in ekin scale, introduce faclim
45// 19.10.06 V.Ivanchenko use inheritance from G4eCoulombScatteringModel
46// 09.10.07 V.Ivanchenko reorganized methods, add cut dependence in scattering off e-
47// 09.06.08 V.Ivanchenko SelectIsotope is moved to the base class
48// 16.06.09 Consolandi rows 109, 111-112, 183, 185-186
49//
50//
51// Class Description:
52//
53// -------------------------------------------------------------------
54//
55//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
56//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
57
58#include "G4CoulombScatteringModel.hh"
59#include "Randomize.hh"
60#include "G4ParticleChangeForGamma.hh"
61#include "G4ParticleTable.hh"
62#include "G4IonTable.hh"
63#include "G4Proton.hh"
64
65//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
66
67using namespace std;
68
69G4CoulombScatteringModel::G4CoulombScatteringModel(const G4String& nam)
70  : G4eCoulombScatteringModel(nam)
71{}
72
73//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
74
75G4CoulombScatteringModel::~G4CoulombScatteringModel()
76{}
77
78//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
79
80G4double G4CoulombScatteringModel::ComputeCrossSectionPerAtom(
81                                const G4ParticleDefinition* p,
82                                G4double kinEnergy, 
83                                G4double Z, 
84                                G4double, 
85                                G4double cutEnergy,
86                                G4double)
87{
88  SetupParticle(p);
89  if(kinEnergy < lowEnergyLimit) return 0.0;
90  SetupKinematic(kinEnergy, cutEnergy);
91
92  // save lab system kinematics
93  G4double xtkin = tkin;
94  G4double xmom2 = mom2;
95  G4double xinvb = invbeta2;
96
97  // CM system
98  iz            = G4int(Z);
99  G4double m2   = fNistManager->GetAtomicMassAmu(iz)*amu_c2;
100  G4double etot = tkin + mass;
101  G4double ptot = sqrt(mom2);
102
103  G4double m12  = mass*mass;
104  G4double momCM= ptot*m2/sqrt(m12 + m2*m2 + 2.0*etot*m2);
105
106  mom2 = momCM*momCM;
107  tkin = sqrt(mom2 + m12) - mass;
108
109  //invbeta2 = 1.0 +  m12/mom2;
110  //  G4double fm = m2/(mass + m2); 
111
112  // 03.09.2009 C.Consaldi
113  G4double Ecm=sqrt(m12 + m2*m2 + 2.0*etot*m2);
114  G4double mu_rel=mass*m2/Ecm;
115
116  invbeta2 = 1.0 +  mu_rel*mu_rel/mom2; 
117  //
118
119  SetupTarget(Z, tkin);
120
121  G4double xsec = CrossSectionPerAtom();
122
123  // restore Lab system kinematics
124  tkin = xtkin;
125  mom2 = xmom2;
126  invbeta2 = xinvb;
127
128  return xsec;
129}
130
131//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
132
133void G4CoulombScatteringModel::SampleSecondaries(
134                               std::vector<G4DynamicParticle*>* fvect,
135                               const G4MaterialCutsCouple* couple,
136                               const G4DynamicParticle* dp,
137                               G4double cutEnergy, 
138                               G4double)
139{
140  G4double kinEnergy = dp->GetKineticEnergy();
141  if(kinEnergy < lowEnergyLimit) return;
142  DefineMaterial(couple);
143  SetupParticle(dp->GetDefinition());
144  SetupKinematic(kinEnergy, cutEnergy);
145
146  // Choose nucleus
147  currentElement = SelectRandomAtom(couple,particle,
148                                    kinEnergy,ecut,kinEnergy);
149
150  G4double Z  = currentElement->GetZ();
151  iz          = G4int(Z);
152  G4int ia    = SelectIsotopeNumber(currentElement);
153  G4double m2 = theParticleTable->GetIonTable()->GetNucleusMass(iz, ia);
154
155  // CM system
156  G4double etot = tkin + mass;
157  G4double ptot = sqrt(mom2);
158
159  G4double momCM= ptot*m2/sqrt(mass*mass + m2*m2 + 2.0*etot*m2);
160  mom2 = momCM*momCM;
161  G4double m12 = mass*mass;
162  G4double eCM = sqrt(mom2 + m12);
163
164  // a correction for heavy projectile
165  //  G4double fm = m2/(mass + m2);
166  //  invbeta2 = 1.0 +  m12*fm*fm/mom2;
167
168  // 03.09.2009 C.Consaldi
169  G4double Ecm=sqrt(m12 + m2*m2 + 2.0*etot*m2);
170  G4double mu_rel=mass*m2/Ecm;
171
172  invbeta2 = 1.0 +  mu_rel*mu_rel/mom2;
173  //
174
175  // sample scattering angle in CM system
176  SetupTarget(Z, eCM - mass);
177
178  G4double cost = SampleCosineTheta();
179  G4double z1   = 1.0 - cost;
180  if(z1 < 0.0) return;
181  G4double sint = sqrt(z1*(1.0 + cost));
182  G4double phi  = twopi * G4UniformRand();
183
184  // kinematics in the Lab system
185  G4double bet  = ptot/(etot + m2);
186  G4double gam  = 1.0/sqrt((1.0 - bet)*(1.0 + bet));
187  G4double pzCM = momCM*cost;
188
189  G4ThreeVector v1(momCM*cos(phi)*sint,momCM*sin(phi)*sint,gam*(pzCM + bet*eCM));
190  G4ThreeVector dir = dp->GetMomentumDirection(); 
191  G4ThreeVector newDirection = v1.unit();
192  newDirection.rotateUz(dir);   
193  fParticleChange->ProposeMomentumDirection(newDirection);   
194
195 //   G4double elab = gam*(eCM + bet*pzCM);
196
197 // G4double Ecm  = sqrt(mass*mass + m2*m2 + 2.0*etot*m2);
198  G4double elab = etot - m2*(ptot/Ecm)*(ptot/Ecm)*(1.-cost) ;
199
200 
201  G4double finalT = elab - mass;
202  if(finalT < 0.0) finalT = 0.0;
203  fParticleChange->SetProposedKineticEnergy(finalT);
204
205  // recoil
206  G4double erec = kinEnergy - finalT;
207
208  G4double tcut = recoilThreshold;
209  if(pCuts) { tcut= std::max(tcut,(*pCuts)[currentMaterialIndex]); } 
210
211  if(erec > tcut) {
212    G4ParticleDefinition* ion = theParticleTable->FindIon(iz, ia, 0, iz);
213    G4double plab = sqrt(finalT*(finalT + 2.0*mass));
214    G4ThreeVector p2 = (ptot*dir - plab*newDirection).unit();
215    G4DynamicParticle* newdp  = new G4DynamicParticle(ion, p2, erec);
216    fvect->push_back(newdp);
217  } else if(erec > 0.0) {
218    fParticleChange->ProposeLocalEnergyDeposit(erec);
219    fParticleChange->ProposeNonIonizingEnergyDeposit(erec);
220  }
221}
222
223//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
224
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