Geant4  10.01.p02
G4IonCoulombCrossSection.cc
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26 // G4IonCoulombCrossSection.cc
27 //-------------------------------------------------------------------
28 //
29 // GEANT4 Class header file
30 //
31 // File name: G4IonCoulombCrossSection
32 //
33 // Author: Cristina Consolandi
34 //
35 // Creation date: 05.10.2010 from G4eCoulombScatteringModel
36 //
37 // Class Description:
38 // Computation of Screen-Coulomb Cross Section
39 // for protons, alpha and heavy Ions
40 //
41 //
42 // Reference:
43 // M.J. Boschini et al. "Nuclear and Non-Ionizing Energy-Loss
44 // for Coulomb Scattered Particles from Low Energy up to Relativistic
45 // Regime in Space Radiation Environment"
46 // Accepted for publication in the Proceedings of the ICATPP Conference
47 // on Cosmic Rays for Particle and Astroparticle Physics, Villa Olmo, 7-8
48 // October, 2010, to be published by World Scientific (Singapore).
49 //
50 // Available for downloading at:
51 // http://arxiv.org/abs/1011.4822
52 //
53 // -------------------------------------------------------------------
54 //
55 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
56 
58 #include "G4PhysicalConstants.hh"
59 #include "Randomize.hh"
60 #include "G4Proton.hh"
61 #include "G4Exp.hh"
62 #include "G4Log.hh"
63 
64 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
65 
66 using namespace std;
67 
68 const G4double a0 = CLHEP::electron_mass_c2/0.88534;
69 
71  cosThetaMin(1.0),
72  cosThetaMax(-1.0),
73  alpha2(fine_structure_const*fine_structure_const)
74 {
77  particle=0;
78 
79  G4double p0 = electron_mass_c2*classic_electr_radius;
80  coeff = twopi*p0*p0;
81 
82  cosTetMinNuc=0;
83  cosTetMaxNuc=0;
84  nucXSection =0;
85 
86  chargeSquare = spin = mass = 0.0;
87  tkinLab = momLab2 = invbetaLab2 = tkin = mom2 = invbeta2 = 0.0;
88 
90 }
91 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
92 
94 {}
95 
96 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
97 
99  G4double CosThetaLim)
100 {
101  SetupParticle(p);
102  nucXSection = 0.0;
103  tkin = targetZ = mom2 = DBL_MIN;
104  ecut = etag = DBL_MAX;
105  particle = p;
106  cosThetaMin = CosThetaLim;
107 }
108 
109 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
110 
112  G4double cut, G4double tmass)
113 {
114  if(ekin != tkinLab || ecut != cut || tmass != targetMass) {
115 
116  // lab
117  tkinLab = ekin;
118  momLab2 = tkinLab*(tkinLab + 2.0*mass);
119  invbetaLab2 = 1.0 + mass*mass/momLab2;
120 
121  G4double etot = tkinLab + mass;
122  G4double ptot = sqrt(momLab2);
123  G4double m12 = mass*mass;
124 
125  targetMass = tmass;
126  // relativistic reduced mass from publucation
127  // A.P. Martynenko, R.N. Faustov, Teoret. mat. Fiz. 64 (1985) 179
128 
129  //incident particle & target nucleus
130  G4double Ecm=sqrt(m12 + targetMass*targetMass + 2.0*etot*targetMass);
131  G4double mu_rel=mass*targetMass/Ecm;
132  G4double momCM= ptot*targetMass/Ecm;
133  // relative system
134  mom2 = momCM*momCM;
135  invbeta2 = 1.0 + mu_rel*mu_rel/mom2;
136  tkin = momCM*sqrt(invbeta2) - mu_rel;//Ekin of mu_rel
137 
140  }
141 }
142 
143 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
144 
146  G4int heavycorr)
147 {
148  if(Z != targetZ || e != etag) {
149  etag = e;
150  targetZ = Z;
151  G4int iz= G4lrint(Z);
152 
153  SetScreenRSquare(iz);
154  screenZ = 0;
156  // G4cout<< "heavycorr "<<heavycorr<<G4endl;
157 
158  if(heavycorr!=0 && particle != theProton){
159  G4double corr=5.*twopi*Z*std::sqrt(chargeSquare*alpha2);
160  corr=G4Exp(G4Log(corr)*0.12);
161  screenZ *=0.5*(1.13 + corr*3.76*Z*Z*chargeSquare*invbeta2*alpha2);
162  // G4cout<<" heavycorr Z e corr....2As "<< heavycorr << "\t"
163  // <<Z <<"\t"<<e/MeV <<"\t"<<screenZ<<G4endl;
164  }else{
165  screenZ *= 0.5*(1.13 + 3.76*Z*Z*chargeSquare*invbeta2*alpha2);
166  // G4cout<<" heavycorr Z e....2As "<< heavycorr << "\t"
167  // <<Z <<"\t"<< e/MeV <<"\t" <<screenZ<<G4endl;
168  }
169 
170  if(1 == iz && particle == theProton && cosTetMaxNuc < 0.0) {
171  cosTetMaxNuc = 0.0;
172  }
173  }
174 }
175 
176 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
177 
179 {
180  //for proton Thomas-Fermi screening length
181  G4int Z1 = G4lrint(std::sqrt(chargeSquare));
182  G4double Z1023 = G4Exp(fNistManager->GetLOGZ(Z1)*0.23);
183  G4double Z2023 = G4Exp(fNistManager->GetLOGZ(iz)*0.23);
184 
185  // Universal screening length
186  G4double x = a0*(Z1023+Z2023);
187 
188  ScreenRSquare = alpha2*x*x;
189 }
190 
191 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
192 
194 {
195  // This method needs initialisation before be called
196  // scattering with target nucleus
198 
199  nucXSection = 0.0;
200 
201  G4double x = 1.0 - cosTetMinNuc;
202  G4double x1 = x + screenZ;
203 
204  // scattering with nucleus
205  if(cosTetMaxNuc < cosTetMinNuc) {
206  nucXSection = fac*(cosTetMinNuc - cosTetMaxNuc)/
207  (x1*(1.0 - cosTetMaxNuc + screenZ));
208  }
209 
210  return nucXSection;
211 }
212 
213 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
214 
216 {
217  G4double z1 = 0.0;
218  if(cosTetMaxNuc < cosTetMinNuc) {
219 
220  G4double x1 = 1. - cosTetMinNuc + screenZ;
221  G4double x2 = 1. - cosTetMaxNuc + screenZ;
223  z1 = x1*x2/(x1 + G4UniformRand()*dx) - screenZ;
224  }
225  return z1;
226 }
227 
228 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
229 
230 
231 
232 
void SetupTarget(G4double Z, G4double kinEnergy, G4int heavycorr)
const G4double a0
const G4ParticleDefinition * theProton
int G4int
Definition: G4Types.hh:78
static G4NistManager * Instance()
const G4ParticleDefinition * particle
#define G4UniformRand()
Definition: Randomize.hh:93
void SetupParticle(const G4ParticleDefinition *)
G4double iz
Definition: TRTMaterials.hh:39
static G4Proton * Proton()
Definition: G4Proton.cc:93
G4double G4Log(G4double x)
Definition: G4Log.hh:230
G4double G4Exp(G4double initial_x)
Exponential Function double precision.
Definition: G4Exp.hh:183
const G4double p0
int G4lrint(double ad)
Definition: templates.hh:163
#define DBL_MIN
Definition: templates.hh:75
G4double GetLOGZ(G4int Z)
static const G4double fac
void SetupKinematic(G4double kinEnergy, G4double cut, G4double tmass)
double G4double
Definition: G4Types.hh:76
#define DBL_MAX
Definition: templates.hh:83
void Initialise(const G4ParticleDefinition *, G4double cosThetaLim)