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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 
69 
71  cosThetaMin(1.0),
72  cosThetaMax(-1.0),
74 {
75  fNistManager = G4NistManager::Instance();
76  fG4pow = G4Pow::GetInstance();
77  theProton = G4Proton::Proton();
78  particle=0;
79 
81  coeff = twopi*p0*p0;
82 
83  cosTetMinNuc=0;
84  cosTetMaxNuc=0;
85  nucXSection =0;
86 
87  chargeSquare = spin = mass = 0.0;
88  tkinLab = momLab2 = invbetaLab2 = tkin = mom2 = invbeta2 = 0.0;
89 
90  targetZ = targetMass = screenZ = ScreenRSquare = etag = 0.0;
91 }
92 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
93 
95 {}
96 
97 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
98 
100  G4double CosThetaLim)
101 {
102  SetupParticle(p);
103  nucXSection = tkin = targetZ = mom2 = 0.0;
104  etag = DBL_MAX;
105  particle = p;
106  cosThetaMin = CosThetaLim;
107 }
108 
109 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
110 
112 {
113  if(ekin != tkinLab || tmass != targetMass) {
114 
115  // lab
116  tkinLab = ekin;
117  momLab2 = tkinLab*(tkinLab + 2.0*mass);
118  invbetaLab2 = 1.0 + mass*mass/momLab2;
119 
120  G4double etot = tkinLab + mass;
121  G4double ptot = sqrt(momLab2);
122  G4double m12 = mass*mass;
123  // relativistic reduced mass from publucation
124  // A.P. Martynenko, R.N. Faustov, Teoret. mat. Fiz. 64 (1985) 179
125 
126  //incident particle & target nucleus
127  targetMass = tmass;
128  G4double Ecm=sqrt(m12 + targetMass*targetMass + 2.0*etot*targetMass);
129  G4double mu_rel=mass*targetMass/Ecm;
130  G4double momCM= ptot*targetMass/Ecm;
131  // relative system
132  mom2 = momCM*momCM;
133  invbeta2 = 1.0 + mu_rel*mu_rel/mom2;
134  tkin = momCM*sqrt(invbeta2) - mu_rel;//Ekin of mu_rel
135 
136  cosTetMinNuc = cosThetaMin;
137  cosTetMaxNuc = cosThetaMax;
138  }
139 }
140 
141 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
142 
144  G4int)
145 {
146  if(Z != targetZ || e != etag) {
147  etag = e;
148  targetZ = Z;
149  G4int iz= G4lrint(Z);
150 
151  SetScreenRSquare(iz);
152  screenZ = 0;
153  screenZ = ScreenRSquare/mom2;
154  //heavycorr = 0;
155  // G4cout<< "heavycorr "<<heavycorr<<G4endl;
156 
157  G4double corr=5.*twopi*Z*std::sqrt(chargeSquare*alpha2);
158  corr=G4Exp(G4Log(corr)*0.04);
159  screenZ *=0.5*(1.13 + corr*3.76*Z*Z*chargeSquare*invbeta2*alpha2);
160  // G4cout<<" heavycorr Z e corr....2As "<< heavycorr << "\t"
161  // <<Z <<"\t"<<e/MeV <<"\t"<<screenZ<<G4endl;
162 
163  if(1 == iz && particle == theProton && cosTetMaxNuc < 0.0) {
164  cosTetMaxNuc = 0.0;
165  }
166  }
167 }
168 
169 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
170 
171 void G4IonCoulombCrossSection::SetScreenRSquare(G4int iz)
172 {
173  //for proton Thomas-Fermi screening length
174  G4int Z1 = G4lrint(std::sqrt(chargeSquare));
175  G4double Z113 = fG4pow->Z13(iz);
176  G4double Z1023 = fG4pow->powZ(Z1,0.23);
177  G4double Z2023 = fG4pow->powZ(iz,0.23);
178  G4double x=a0*(Z1023+Z2023);
179 
180  // Universal screening length
181  if(particle == theProton){
182  x = a0*Z113;
183  }
184 
185  ScreenRSquare = alpha2*x*x;
186 }
187 
188 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
189 
191 {
192  // This method needs initialisation before be called
193  // scattering with target nucleus
194  G4double fac = coeff*targetZ*(targetZ)*chargeSquare*invbeta2/mom2;
195 
196  nucXSection = 0.0;
197 
198  G4double x = 1.0 - cosTetMinNuc;
199  G4double x1 = x + screenZ;
200 
201  // scattering with nucleus
202  if(cosTetMaxNuc < cosTetMinNuc) {
203  nucXSection = fac*(cosTetMinNuc - cosTetMaxNuc)/
204  (x1*(1.0 - cosTetMaxNuc + screenZ));
205  }
206 
207  return nucXSection;
208 }
209 
210 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
211 
213 {
214  G4double z1 = 0.0;
215  if(cosTetMaxNuc < cosTetMinNuc) {
216 
217  G4double x1 = 1. - cosTetMinNuc + screenZ;
218  G4double x2 = 1. - cosTetMaxNuc + screenZ;
219  G4double dx = cosTetMinNuc - cosTetMaxNuc;
220  z1 = x1*x2/(x1 + G4UniformRand()*dx) - screenZ;
221  }
222  return z1;
223 }
224 
225 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
226 
227 
228 
229 
void SetupTarget(G4double Z, G4double kinEnergy, G4int heavycorr)
const G4double a0
static G4Pow * GetInstance()
Definition: G4Pow.cc:55
void SetupKinematic(G4double kinEnergy, G4double tmass)
const char * p
Definition: xmltok.h:285
tuple x
Definition: test.py:50
int G4int
Definition: G4Types.hh:78
static G4NistManager * Instance()
static constexpr double twopi
Definition: G4SIunits.hh:76
static constexpr double electron_mass_c2
#define G4UniformRand()
Definition: Randomize.hh:97
G4double Z13(G4int Z) const
Definition: G4Pow.hh:127
void SetupParticle(const G4ParticleDefinition *)
static G4Proton * Proton()
Definition: G4Proton.cc:93
float electron_mass_c2
Definition: hepunit.py:274
G4double G4Log(G4double x)
Definition: G4Log.hh:230
G4double G4Exp(G4double initial_x)
Exponential Function double precision.
Definition: G4Exp.hh:183
int G4lrint(double ad)
Definition: templates.hh:163
static const G4double fac
G4double powZ(G4int Z, G4double y) const
Definition: G4Pow.hh:254
double G4double
Definition: G4Types.hh:76
#define DBL_MAX
Definition: templates.hh:83
void Initialise(const G4ParticleDefinition *, G4double cosThetaLim)