Geant4 Cross Reference |
1 // 1 2 // ******************************************* 3 // * License and Disclaimer 4 // * 5 // * The Geant4 software is copyright of th 6 // * the Geant4 Collaboration. It is provided 7 // * conditions of the Geant4 Software License 8 // * LICENSE and available at http://cern.ch/ 9 // * include a list of copyright holders. 10 // * 11 // * Neither the authors of this software syst 12 // * institutes,nor the agencies providing fin 13 // * work make any representation or warran 14 // * regarding this software system or assum 15 // * use. Please see the license in the file 16 // * for the full disclaimer and the limitatio 17 // * 18 // * This code implementation is the result 19 // * technical work of the GEANT4 collaboratio 20 // * By using, copying, modifying or distri 21 // * any work based on the software) you ag 22 // * use in resulting scientific publicati 23 // * acceptance of all terms of the Geant4 Sof 24 // ******************************************* 25 // 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 G4eCoulombSc 36 // 37 // Class Description: 38 // Computation of Screen-Coulomb Cross Sectio 39 // for protons, alpha and heavy Ions 40 // 41 // 42 // Reference: 43 // M.J. Boschini et al. "Nuclear and Non- 44 // for Coulomb Scattered Particles from L 45 // Regime in Space Radiation Environment" 46 // Accepted for publication in the Procee 47 // on Cosmic Rays for Particle and Astrop 48 // October, 2010, to be published by Wor 49 // 50 // Available for downloading at: 51 // http://arxiv.org/abs/1011.4822 52 // 53 // ------------------------------------------- 54 // 55 //....oooOO0OOooo........oooOO0OOooo........oo 56 57 #include "G4IonCoulombCrossSection.hh" 58 #include "G4PhysicalConstants.hh" 59 #include "Randomize.hh" 60 #include "G4Proton.hh" 61 #include "G4Exp.hh" 62 #include "G4Log.hh" 63 64 //....oooOO0OOooo........oooOO0OOooo........oo 65 66 using namespace std; 67 68 const G4double a0 = CLHEP::electron_mass_c2/0. 69 70 G4IonCoulombCrossSection::G4IonCoulombCrossSec 71 cosThetaMin(1.0), 72 cosThetaMax(-1.0), 73 alpha2(fine_structure_const*fine_structure_ 74 { 75 fNistManager = G4NistManager::Instance(); 76 fG4pow = G4Pow::GetInstance(); 77 theProton = G4Proton::Proton(); 78 particle = nullptr; 79 80 G4double p0 = electron_mass_c2*classic_elect 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 = mom 89 90 targetZ = targetMass = screenZ = ScreenRSqua 91 } 92 93 //....oooOO0OOooo........oooOO0OOooo........oo 94 95 void G4IonCoulombCrossSection::Initialise(cons 96 G4do 97 { 98 SetupParticle(p); 99 nucXSection = tkin = targetZ = mom2 = 0.0; 100 etag = DBL_MAX; 101 particle = p; 102 cosThetaMin = CosThetaLim; 103 } 104 105 //....oooOO0OOooo........oooOO0OOooo........oo 106 107 void G4IonCoulombCrossSection::SetupKinematic( 108 { 109 if(ekin != tkinLab || tmass != targetMass) { 110 111 // lab 112 tkinLab = ekin; 113 momLab2 = tkinLab*(tkinLab + 2.0*mass); 114 invbetaLab2 = 1.0 + mass*mass/momLab2; 115 116 G4double etot = tkinLab + mass; 117 G4double ptot = sqrt(momLab2); 118 G4double m12 = mass*mass; 119 // relativistic reduced mass from publucat 120 // A.P. Martynenko, R.N. Faustov, Teoret. 121 122 //incident particle & target nucleus 123 targetMass = tmass; 124 G4double Ecm=sqrt(m12 + targetMass*targetM 125 G4double mu_rel=mass*targetMass/Ecm; 126 G4double momCM= ptot*targetMass/Ecm; 127 // relative system 128 mom2 = momCM*momCM; 129 invbeta2 = 1.0 + mu_rel*mu_rel/mom2; 130 tkin = momCM*sqrt(invbeta2) - mu_rel;//Eki 131 132 cosTetMinNuc = cosThetaMin; 133 cosTetMaxNuc = cosThetaMax; 134 } 135 } 136 137 //....oooOO0OOooo........oooOO0OOooo........oo 138 139 void G4IonCoulombCrossSection::SetupTarget(G4d 140 G4int) 141 { 142 if(Z != targetZ || e != etag) { 143 etag = e; 144 targetZ = Z; 145 G4int iz= G4lrint(Z); 146 147 SetScreenRSquare(iz); 148 screenZ = 0; 149 screenZ = ScreenRSquare/mom2; 150 //heavycorr = 0; 151 // G4cout<< "heavycorr "<<heavycorr<<G4en 152 153 G4double corr=5.*twopi*Z*std::sqrt(chargeS 154 corr=G4Exp(G4Log(corr)*0.04); 155 screenZ *=0.5*(1.13 + corr*3.76*Z*Z*charge 156 // G4cout<<" heavycorr Z e corr....2As "<< 157 // <<Z <<"\t"<<e/MeV <<"\t"<<screenZ<<G4e 158 159 if(1 == iz && particle == theProton && cos 160 cosTetMaxNuc = 0.0; 161 } 162 } 163 } 164 165 //....oooOO0OOooo........oooOO0OOooo........oo 166 167 void G4IonCoulombCrossSection::SetScreenRSquar 168 { 169 //for proton Thomas-Fermi screening length 170 G4int Z1 = G4lrint(std::sqrt(chargeSquare)); 171 G4double Z113 = fG4pow->Z13(iz); 172 G4double Z1023 = fG4pow->powZ(Z1,0.23); 173 G4double Z2023 = fG4pow->powZ(iz,0.23); 174 G4double x=a0*(Z1023+Z2023); 175 176 // Universal screening length 177 if(particle == theProton){ 178 x = a0*Z113; 179 } 180 181 ScreenRSquare = alpha2*x*x; 182 } 183 184 //....oooOO0OOooo........oooOO0OOooo........oo 185 186 G4double G4IonCoulombCrossSection::NuclearCros 187 { 188 // This method needs initialisation before b 189 // scattering with target nucleus 190 G4double fac = coeff*targetZ*(targetZ)*charg 191 192 nucXSection = 0.0; 193 194 G4double x = 1.0 - cosTetMinNuc; 195 G4double x1 = x + screenZ; 196 197 // scattering with nucleus 198 if(cosTetMaxNuc < cosTetMinNuc) { 199 nucXSection = fac*(cosTetMinNuc - cosTetMa 200 (x1*(1.0 - cosTetMaxNuc + screenZ)); 201 } 202 203 return nucXSection; 204 } 205 206 //....oooOO0OOooo........oooOO0OOooo........oo 207 208 G4double G4IonCoulombCrossSection::SampleCosin 209 { 210 G4double z1 = 0.0; 211 if(cosTetMaxNuc < cosTetMinNuc) { 212 213 G4double x1 = 1. - cosTetMinNuc + screenZ; 214 G4double x2 = 1. - cosTetMaxNuc + screenZ; 215 G4double dx = cosTetMinNuc - cosTetMaxNuc; 216 z1 = x1*x2/(x1 + G4UniformRand()*dx) - scr 217 } 218 return z1; 219 } 220 221 //....oooOO0OOooo........oooOO0OOooo........oo 222 223 224 225 226