source: trunk/source/processes/electromagnetic/standard/src/G4CoulombScatteringModel.cc @ 1197

Last change on this file since 1197 was 1196, checked in by garnier, 15 years ago

update CVS release candidate geant4.9.3.01
File size: 7.1 KB
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26// $Id: G4CoulombScatteringModel.cc,v 1.43 2009/10/28 10:14:13 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-03-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//
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 
111  G4double fm = m2/(mass + m2);
112  invbeta2 = 1.0 +  m12*fm*fm/mom2;
113
114  SetupTarget(Z, tkin);
115
116  G4double xsec = CrossSectionPerAtom();
117
118  // restore Lab system kinematics
119  tkin = xtkin;
120  mom2 = xmom2;
121  invbeta2 = xinvb;
122
123  return xsec;
124}
125
126//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
127
128void G4CoulombScatteringModel::SampleSecondaries(
129                               std::vector<G4DynamicParticle*>* fvect,
130                               const G4MaterialCutsCouple* couple,
131                               const G4DynamicParticle* dp,
132                               G4double cutEnergy, 
133                               G4double)
134{
135  G4double kinEnergy = dp->GetKineticEnergy();
136  if(kinEnergy < lowEnergyLimit) return;
137  DefineMaterial(couple);
138  SetupParticle(dp->GetDefinition());
139  SetupKinematic(kinEnergy, cutEnergy);
140
141  // Choose nucleus
142  currentElement = SelectRandomAtom(couple,particle,
143                                    kinEnergy,ecut,kinEnergy);
144
145  G4double Z  = currentElement->GetZ();
146  iz          = G4int(Z);
147  G4int ia    = SelectIsotopeNumber(currentElement);
148  G4double m2 = theParticleTable->GetIonTable()->GetNucleusMass(iz, ia);
149
150  // CM system
151  G4double etot = tkin + mass;
152  G4double ptot = sqrt(mom2);
153
154  G4double momCM= ptot*m2/sqrt(mass*mass + m2*m2 + 2.0*etot*m2);
155  mom2 = momCM*momCM;
156  G4double m12 = mass*mass;
157  G4double eCM = sqrt(mom2 + m12);
158
159  // a correction for heavy projectile
160  G4double fm = m2/(mass + m2);
161  invbeta2 = 1.0 +  m12*fm*fm/mom2;
162
163  // sample scattering angle in CM system
164  SetupTarget(Z, eCM - mass);
165
166  G4double cost = SampleCosineTheta();
167  G4double z1   = 1.0 - cost;
168  if(z1 < 0.0) return;
169  G4double sint = sqrt(z1*(1.0 + cost));
170  G4double phi  = twopi * G4UniformRand();
171
172  // kinematics in the Lab system
173  G4double bet  = ptot/(etot + m2);
174  G4double gam  = 1.0/sqrt((1.0 - bet)*(1.0 + bet));
175  G4double pzCM = momCM*cost;
176
177  G4ThreeVector v1(momCM*cos(phi)*sint,momCM*sin(phi)*sint,gam*(pzCM + bet*eCM));
178  G4ThreeVector dir = dp->GetMomentumDirection(); 
179  G4ThreeVector newDirection = v1.unit();
180  newDirection.rotateUz(dir);   
181  fParticleChange->ProposeMomentumDirection(newDirection);   
182
183  //  G4double elab = gam*(eCM + bet*pzCM);
184
185  G4double Ecm  = sqrt(mass*mass + m2*m2 + 2.0*etot*m2);
186  G4double elab = etot - m2*(ptot/Ecm)*(ptot/Ecm)*(1.-cost) ;
187
188 
189  G4double finalT = elab - mass;
190  if(finalT < 0.0) finalT = 0.0;
191  fParticleChange->SetProposedKineticEnergy(finalT);
192
193  // recoil
194  G4double erec = kinEnergy - finalT;
195
196  G4double tcut = recoilThreshold;
197  if(pCuts) { tcut= std::max(tcut,(*pCuts)[currentMaterialIndex]); } 
198
199  if(erec > tcut) {
200    G4ParticleDefinition* ion = theParticleTable->FindIon(iz, ia, 0, iz);
201    G4double plab = sqrt(finalT*(finalT + 2.0*mass));
202    G4ThreeVector p2 = (ptot*dir - plab*newDirection).unit();
203    G4DynamicParticle* newdp  = new G4DynamicParticle(ion, p2, erec);
204    fvect->push_back(newdp);
205  } else if(erec > 0.0) {
206    fParticleChange->ProposeLocalEnergyDeposit(erec);
207    fParticleChange->ProposeNonIonizingEnergyDeposit(erec);
208  }
209}
210
211//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
212
213
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