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2 | // ******************************************************************** |
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24 | // ******************************************************************** |
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25 | // |
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26 | // |
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27 | // G4ScreenedNuclearRecoil.hh,v 1.24 2008/05/01 19:58:59 marcus Exp |
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28 | // GEANT4 tag |
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29 | // |
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30 | // |
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31 | // |
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32 | // Class Description |
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33 | // Process for screened electromagnetic nuclear elastic scattering; |
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34 | // Physics comes from: |
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35 | // Marcus H. Mendenhall and Robert A. Weller, |
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36 | // "Algorithms for the rapid computation of classical cross sections |
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37 | // for screened Coulomb collisions " |
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38 | // Nuclear Instruments and Methods in Physics Research B58 (1991) 11-17 |
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39 | // The only input required is a screening function phi(r/a) which is the ratio |
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40 | // of the actual interatomic potential for two atoms with atomic numbers Z1 and Z2, |
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41 | // to the unscreened potential Z1*Z2*e^2/r where e^2 is elm_coupling in Geant4 units |
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42 | // the actual screening tables are computed externally in a python module "screened_scattering.py" |
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43 | // to allow very specific screening functions to be added if desired, without messing |
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44 | // with the insides of this code. |
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45 | // |
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46 | // First version, April 2004, Marcus H. Mendenhall, Vanderbilt University |
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47 | // May 1, 2008 -- Added code to allow process to have zero cross section above max energy, to coordinate with G4MSC. -- mhm |
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48 | // |
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49 | // Class Description - End |
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50 | |
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51 | |
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52 | #ifndef G4ScreenedNuclearRecoil_h |
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53 | #define G4ScreenedNuclearRecoil_h 1 |
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54 | |
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55 | #include "globals.hh" |
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56 | #include "G4VDiscreteProcess.hh" |
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57 | #include "G4ParticleChange.hh" |
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58 | #include "c2_function.hh" |
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59 | |
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60 | #include <map> |
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61 | #include <vector> |
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62 | |
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63 | class G4VNIELPartition; |
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64 | |
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65 | typedef c2_const_ptr<G4double> G4_c2_const_ptr; |
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66 | typedef c2_ptr<G4double> G4_c2_ptr; |
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67 | typedef c2_function<G4double> G4_c2_function; |
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68 | |
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69 | typedef struct G4ScreeningTables { |
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70 | G4double z1, z2, m1, m2, au, emin; |
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71 | G4_c2_const_ptr EMphiData; |
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72 | } G4ScreeningTables; |
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73 | |
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74 | // A class for loading ScreenedCoulombCrossSections |
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75 | class G4ScreenedCoulombCrossSectionInfo |
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76 | { |
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77 | public: |
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78 | G4ScreenedCoulombCrossSectionInfo() { } |
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79 | ~G4ScreenedCoulombCrossSectionInfo() { } |
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80 | |
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81 | static const char* CVSHeaderVers() { return |
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82 | "G4ScreenedNuclearRecoil.hh,v 1.24 2008/05/01 19:58:59 marcus Exp GEANT4 tag "; |
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83 | } |
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84 | static const char* CVSFileVers(); |
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85 | }; |
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86 | |
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87 | // A class for loading ScreenedCoulombCrossSections |
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88 | class G4ScreenedCoulombCrossSection : public G4ScreenedCoulombCrossSectionInfo |
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89 | { |
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90 | public: |
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91 | |
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92 | G4ScreenedCoulombCrossSection() : verbosity(1) { } |
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93 | G4ScreenedCoulombCrossSection(const G4ScreenedCoulombCrossSection &src) : |
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94 | G4ScreenedCoulombCrossSectionInfo(),verbosity(src.verbosity) { } |
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95 | virtual ~G4ScreenedCoulombCrossSection(); |
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96 | |
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97 | typedef std::map<G4int, G4ScreeningTables> ScreeningMap; |
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98 | |
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99 | // a local, fast-access mapping of a particle's Z to its full definition |
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100 | typedef std::map<G4int, class G4ParticleDefinition *> ParticleCache; |
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101 | |
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102 | // LoadData is called by G4ScreenedNuclearRecoil::GetMeanFreePath |
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103 | // It loads the data tables, builds the elemental cross-section tables. |
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104 | virtual void LoadData(G4String screeningKey, G4int z1, G4double m1, G4double recoilCutoff) = 0; |
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105 | |
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106 | // BuildMFPTables is called by G4ScreenedNuclearRecoil::GetMeanFreePath to build the MFP tables for each material |
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107 | void BuildMFPTables(void); // scan the MaterialsTable and construct MFP tables |
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108 | |
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109 | virtual G4ScreenedCoulombCrossSection *create() = 0; // a 'virtual constructor' which clones the class |
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110 | const G4ScreeningTables *GetScreening(G4int Z) { return &(screeningData[Z]); } |
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111 | void SetVerbosity(G4int v) { verbosity=v; } |
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112 | |
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113 | // this process needs element selection weighted only by number density |
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114 | G4ParticleDefinition* SelectRandomUnweightedTarget(const G4MaterialCutsCouple* couple); |
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115 | |
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116 | enum { nMassMapElements=116 }; |
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117 | |
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118 | G4double standardmass(G4int z1) { return z1 <= nMassMapElements ? massmap[z1] : 2.5*z1; } |
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119 | |
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120 | // get the mean-free-path table for the indexed material |
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121 | const G4_c2_function * operator [] (G4int materialIndex) { |
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122 | return MFPTables.find(materialIndex)!=MFPTables.end() ? &(MFPTables[materialIndex].get()) : (G4_c2_function *)0; |
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123 | } |
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124 | |
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125 | protected: |
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126 | ScreeningMap screeningData; // screening tables for each element |
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127 | ParticleCache targetMap; |
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128 | G4int verbosity; |
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129 | std::map<G4int, G4_c2_const_ptr > sigmaMap; // total cross section for each element |
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130 | std::map<G4int, G4_c2_const_ptr > MFPTables; // MFP for each material |
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131 | |
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132 | private: |
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133 | static const G4double massmap[nMassMapElements+1]; |
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134 | |
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135 | }; |
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136 | |
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137 | typedef struct G4CoulombKinematicsInfo { |
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138 | G4double impactParameter; |
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139 | G4ScreenedCoulombCrossSection *crossSection; |
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140 | G4double a1, a2, sinTheta, cosTheta, sinZeta, cosZeta, eRecoil; |
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141 | G4ParticleDefinition *recoilIon; |
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142 | const G4Material *targetMaterial; |
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143 | } G4CoulombKinematicsInfo; |
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144 | |
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145 | class G4ScreenedCollisionStage { |
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146 | public: |
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147 | virtual void DoCollisionStep(class G4ScreenedNuclearRecoil *master, |
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148 | const class G4Track& aTrack, const class G4Step& aStep)=0; |
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149 | virtual ~G4ScreenedCollisionStage() {} |
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150 | }; |
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151 | |
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152 | class G4ScreenedCoulombClassicalKinematics: public G4ScreenedCoulombCrossSectionInfo, public G4ScreenedCollisionStage { |
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153 | |
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154 | public: |
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155 | G4ScreenedCoulombClassicalKinematics(); |
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156 | virtual void DoCollisionStep(class G4ScreenedNuclearRecoil *master, |
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157 | const class G4Track& aTrack, const class G4Step& aStep); |
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158 | |
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159 | G4bool DoScreeningComputation(class G4ScreenedNuclearRecoil *master, |
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160 | const G4ScreeningTables *screen, |
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161 | G4double eps, G4double beta); |
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162 | virtual ~G4ScreenedCoulombClassicalKinematics() { } |
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163 | protected: |
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164 | // the c2_functions we need to do the work. |
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165 | c2_const_plugin_function_p<G4double> &phifunc; |
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166 | c2_linear_p<G4double> &xovereps; |
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167 | G4_c2_ptr diff; |
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168 | |
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169 | }; |
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170 | |
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171 | class G4SingleScatter: public G4ScreenedCoulombCrossSectionInfo, public G4ScreenedCollisionStage { |
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172 | |
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173 | public: |
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174 | G4SingleScatter() { } |
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175 | virtual void DoCollisionStep(class G4ScreenedNuclearRecoil *master, |
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176 | const class G4Track& aTrack, const class G4Step& aStep); |
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177 | virtual ~G4SingleScatter() {} |
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178 | }; |
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179 | |
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180 | /** |
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181 | \brief A process which handles screened Coulomb collisions between nuclei |
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182 | |
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183 | */ |
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184 | |
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185 | class G4ScreenedNuclearRecoil : public G4ScreenedCoulombCrossSectionInfo, public G4VDiscreteProcess |
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186 | { |
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187 | public: |
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188 | |
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189 | friend class G4ScreenedCollisionStage; |
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190 | |
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191 | /// \brief Construct the process and set some physics parameters for it. |
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192 | /// \param processName the name to assign the process |
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193 | /// \param ScreeningKey the name of a screening function to use. |
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194 | /// The default functions are "zbl" (recommended for soft scattering), |
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195 | /// "lj" (recommended for backscattering) and "mol" (Moliere potential) |
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196 | /// \param GenerateRecoils if frue, ions struck by primary are converted into new moving particles. |
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197 | /// If false, energy is deposited, but no new moving ions are created. |
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198 | /// \param RecoilCutoff energy below which no new moving particles will be created, |
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199 | /// even if \a GenerateRecoils is true. |
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200 | /// Also, a moving primary particle will be stopped if its energy falls below this limit. |
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201 | /// \param PhysicsCutoff the energy transfer to which screening tables are calucalted. |
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202 | /// There is no really |
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203 | /// compelling reason to change it from the 10.0 eV default. However, see the paper on running this |
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204 | /// in thin targets for further discussion, and its interaction with SetMFPScaling() |
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205 | G4ScreenedNuclearRecoil(const G4String& processName = "ScreenedElastic", |
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206 | const G4String &ScreeningKey="zbl", G4bool GenerateRecoils=1, |
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207 | G4double RecoilCutoff=100.0*eV, G4double PhysicsCutoff=10.0*eV); |
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208 | /// \brief destructor |
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209 | virtual ~G4ScreenedNuclearRecoil(); |
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210 | /// \brief used internally by Geant4 machinery |
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211 | virtual G4double GetMeanFreePath(const G4Track&, G4double, G4ForceCondition* ); |
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212 | /// \brief used internally by Geant4 machinery |
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213 | virtual G4VParticleChange* PostStepDoIt(const G4Track& aTrack, const G4Step& aStep); |
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214 | /// \brief test if a prticle of type \a aParticleType can use this process |
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215 | /// \param aParticleType the particle to test |
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216 | virtual G4bool IsApplicable(const G4ParticleDefinition& aParticleType); |
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217 | /// \brief Build physics tables in advance. Not Implemented. |
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218 | /// \param aParticleType the type of particle to build tables for |
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219 | virtual void BuildPhysicsTable(const G4ParticleDefinition&) { } |
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220 | /// \brief Export physics tables for persistency. Not Implemented. |
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221 | /// \param aParticleType the type of particle to build tables for |
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222 | virtual void DumpPhysicsTable(const G4ParticleDefinition& aParticleType); |
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223 | /// \brief deterine if the moving particle is within the strong force range of the selected nucleus |
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224 | /// \param A the nucleon number of the beam |
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225 | /// \param A1 the nucleon number of the target |
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226 | /// \param apsis the distance of closest approach |
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227 | virtual G4bool CheckNuclearCollision(G4double A, G4double A1, G4double apsis); // return true if hard collision |
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228 | |
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229 | virtual G4ScreenedCoulombCrossSection *GetNewCrossSectionHandler(void); |
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230 | |
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231 | /// \brief Get non-ionizing energy loss for last step |
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232 | G4double GetNIEL() const { return NIEL; } |
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233 | |
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234 | /// \brief clear precomputed screening tables |
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235 | void ResetTables(); // clear all data tables to allow changing energy cutoff, materials, etc. |
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236 | |
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237 | /// \brief set the upper energy beyond which this process has no cross section |
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238 | /// |
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239 | /// This funciton is used to coordinate this process with G4MSC. Typically, G4MSC should |
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240 | /// not be allowed to operate in a range which overlaps that of this process. The criterion which is most reasonable |
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241 | /// is that the transition should be somewhere in the modestly relativistic regime (500 MeV/u for example). |
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242 | /// \param energy energy per nucleon for the cutoff |
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243 | void SetMaxEnergyForScattering(G4double energy) { processMaxEnergy=energy; } |
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244 | /// \brief find out what screening funciton we are using |
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245 | std::string GetScreeningKey() const { return screeningKey; } |
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246 | /// \brief enable or disable all energy deposition by this process |
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247 | /// \param flag if true, enable deposition of energy (the default). If false, disable deposition. |
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248 | void AllowEnergyDeposition(G4bool flag) { registerDepositedEnergy=flag; } |
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249 | /// \brief get flag indicating whether deposition is enabled |
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250 | G4bool GetAllowEnergyDeposition() const { return registerDepositedEnergy; } |
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251 | /// \brief enable or disable the generation of recoils. |
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252 | /// If recoils are disabled, the energy they would have received is just deposited. |
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253 | /// \param flag if true, create recoil ions in cases in which the energy is above the recoilCutoff. |
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254 | /// If false, just deposit the energy. |
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255 | void EnableRecoils(G4bool flag) { generateRecoils=flag; } |
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256 | /// \brief find out if generation of recoils is enabled. |
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257 | G4bool GetEnableRecoils() const { return generateRecoils; } |
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258 | /// \brief set the mean free path scaling as specified |
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259 | /// \param scale the factor by which the default MFP will be scaled. |
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260 | /// Set to less than 1 for very thin films, typically, to sample multiple scattering, |
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261 | /// or to greater than 1 for quick simulaitons with a very long flight path. |
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262 | void SetMFPScaling(G4double scale) { MFPScale=scale; } |
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263 | /// \brief get the MFPScaling parameter |
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264 | G4double GetMFPScaling() const { return MFPScale; } |
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265 | /// \brief enable or disable whether this process will skip collisions |
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266 | /// which are close enough they need hadronic phsyics. Default is true (skip close collisions). |
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267 | /// Disabling this results in excess nuclear stopping power. |
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268 | /// \param flag true results in hard collisions being skipped. false allows hard collisions. |
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269 | void AvoidNuclearReactions(G4bool flag) { avoidReactions=flag; } |
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270 | /// \brief get the flag indicating whether hadronic collisions are ignored. |
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271 | G4bool GetAvoidNuclearReactions() const { return avoidReactions; } |
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272 | /// \brief set the minimum energy (per nucleon) at which recoils can be generated, |
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273 | /// and the energy (per nucleon) below which all ions are stopped. |
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274 | /// \param energy energy per nucleon |
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275 | void SetRecoilCutoff(G4double energy) { recoilCutoff=energy; } |
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276 | /// \brief get the recoil cutoff |
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277 | G4double GetRecoilCutoff() const { return recoilCutoff; } |
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278 | /// \brief set the energy to which screening tables are computed. Typically, this is 10 eV or so, and not often changed. |
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279 | /// \param energy the cutoff energy |
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280 | void SetPhysicsCutoff(G4double energy) { physicsCutoff=energy; ResetTables(); } |
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281 | /// \brief get the physics cutoff energy. |
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282 | G4double GetPhysicsCutoff() const { return physicsCutoff; } |
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283 | /// \brief set the pointer to a class for paritioning energy into NIEL |
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284 | /// \brief part the pointer to the class. |
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285 | void SetNIELPartitionFunction(const G4VNIELPartition *part); |
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286 | /// \brief set the cross section boost to provide faster computation of backscattering |
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287 | /// \param fraction the fraction of particles to have their cross section boosted. |
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288 | /// \param HardeningFactor the factor by which to boost the scattering cross section. |
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289 | void SetCrossSectionHardening(G4double fraction, G4double HardeningFactor) { |
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290 | hardeningFraction=fraction; |
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291 | hardeningFactor=HardeningFactor; |
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292 | } |
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293 | /// \brief get the fraction of particles which will have boosted scattering |
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294 | G4double GetHardeningFraction() const { return hardeningFraction; } |
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295 | /// \brief get the boost factor in use. |
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296 | G4double GetHardeningFactor() const { return hardeningFactor; } |
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297 | /// \brief the the interaciton length used in the last scattering. |
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298 | G4double GetCurrentInteractionLength() const { return currentInteractionLength; } |
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299 | /// \brief set a function to compute screening tables, if the user needs non-standard behavior. |
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300 | /// \param cs a class which constructs the screening tables. |
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301 | void SetExternalCrossSectionHandler(G4ScreenedCoulombCrossSection *cs) { |
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302 | externalCrossSectionConstructor=cs; |
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303 | } |
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304 | /// \brief get the verbosity. |
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305 | G4int GetVerboseLevel() const { return verboseLevel; } |
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306 | |
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307 | std::map<G4int, G4ScreenedCoulombCrossSection*> &GetCrossSectionHandlers() |
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308 | { return crossSectionHandlers; } |
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309 | void ClearStages(void); |
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310 | void AddStage(G4ScreenedCollisionStage *stage) { collisionStages.push_back(stage); } |
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311 | G4CoulombKinematicsInfo &GetKinematics() { return kinematics; } |
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312 | void SetValidCollision(G4bool flag) { validCollision=flag; } |
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313 | G4bool GetValidCollision() const { return validCollision; } |
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314 | |
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315 | /// \brief get the pointer to our ParticleChange object. for internal use, primarily. |
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316 | class G4ParticleChange &GetParticleChange() { return static_cast<G4ParticleChange &>(*pParticleChange); } |
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317 | /// \brief take the given energy, and use the material information to partition it into NIEL and ionizing energy. |
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318 | void DepositEnergy(G4int z1, G4double a1, const G4Material *material, G4double energy); |
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319 | |
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320 | protected: |
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321 | /// \brief the energy per nucleon above which the MFP is constant |
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322 | G4double highEnergyLimit; |
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323 | /// \brief the energy per nucleon below which the MFP is zero |
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324 | G4double lowEnergyLimit; |
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325 | /// \brief the energy per nucleon beyond which the cross section is zero, to cross over to G4MSC |
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326 | G4double processMaxEnergy; |
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327 | G4String screeningKey; |
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328 | G4bool generateRecoils, avoidReactions; |
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329 | G4double recoilCutoff, physicsCutoff; |
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330 | G4bool registerDepositedEnergy; |
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331 | G4double IonizingLoss, NIEL; |
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332 | G4double MFPScale; |
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333 | G4double hardeningFraction, hardeningFactor; |
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334 | |
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335 | G4ScreenedCoulombCrossSection *externalCrossSectionConstructor; |
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336 | std::vector<G4ScreenedCollisionStage *> collisionStages; |
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337 | |
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338 | std::map<G4int, G4ScreenedCoulombCrossSection*> crossSectionHandlers; |
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339 | |
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340 | G4bool validCollision; |
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341 | G4CoulombKinematicsInfo kinematics; |
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342 | const G4VNIELPartition *NIELPartitionFunction; |
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343 | }; |
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344 | |
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345 | // A customized G4CrossSectionHandler which gets its data from an external program |
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346 | class G4NativeScreenedCoulombCrossSection: public G4ScreenedCoulombCrossSection |
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347 | { |
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348 | public: |
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349 | G4NativeScreenedCoulombCrossSection(); |
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350 | |
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351 | G4NativeScreenedCoulombCrossSection(const G4NativeScreenedCoulombCrossSection &src) |
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352 | : G4ScreenedCoulombCrossSection(src), phiMap(src.phiMap) { } |
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353 | |
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354 | G4NativeScreenedCoulombCrossSection(const G4ScreenedCoulombCrossSection &src) : G4ScreenedCoulombCrossSection(src) { } |
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355 | virtual ~G4NativeScreenedCoulombCrossSection(); |
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356 | |
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357 | virtual void LoadData(G4String screeningKey, G4int z1, G4double m1, G4double recoilCutoff); |
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358 | virtual G4ScreenedCoulombCrossSection *create() |
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359 | { return new G4NativeScreenedCoulombCrossSection(*this); } |
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360 | // get a list of available keys |
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361 | std::vector<G4String> GetScreeningKeys() const; |
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362 | |
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363 | typedef G4_c2_function &(*ScreeningFunc)(G4int z1, G4int z2, size_t nPoints, G4double rMax, G4double *au); |
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364 | |
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365 | void AddScreeningFunction(G4String name, ScreeningFunc fn) { |
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366 | phiMap[name]=fn; |
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367 | } |
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368 | |
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369 | private: |
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370 | // this is a map used to look up screening function generators |
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371 | std::map<std::string, ScreeningFunc> phiMap; |
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372 | }; |
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373 | |
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374 | G4_c2_function &ZBLScreening(G4int z1, G4int z2, size_t npoints, G4double rMax, G4double *auval); |
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375 | G4_c2_function &MoliereScreening(G4int z1, G4int z2, size_t npoints, G4double rMax, G4double *auval); |
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376 | G4_c2_function &LJScreening(G4int z1, G4int z2, size_t npoints, G4double rMax, G4double *auval); |
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377 | G4_c2_function &LJZBLScreening(G4int z1, G4int z2, size_t npoints, G4double rMax, G4double *auval); |
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378 | |
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379 | #endif |
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