1 | // |
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2 | // ******************************************************************** |
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3 | // * License and Disclaimer * |
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4 | // * * |
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8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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9 | // * include a list of copyright holders. * |
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10 | // * * |
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11 | // * Neither the authors of this software system, nor their employing * |
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12 | // * institutes,nor the agencies providing financial support for this * |
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13 | // * work make any representation or warranty, express or implied, * |
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14 | // * regarding this software system or assume any liability for its * |
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15 | // * use. Please see the license in the file LICENSE and URL above * |
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16 | // * for the full disclaimer and the limitation of liability. * |
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17 | // * * |
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18 | // * This code implementation is the result of the scientific and * |
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19 | // * technical work of the GEANT4 collaboration. * |
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20 | // * By using, copying, modifying or distributing the software (or * |
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21 | // * any work based on the software) you agree to acknowledge its * |
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22 | // * use in resulting scientific publications, and indicate your * |
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23 | // * acceptance of all terms of the Geant4 Software license. * |
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24 | // ******************************************************************** |
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25 | // |
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26 | // $Id: G4PreCompoundNeutron.cc,v 1.5 2010/08/28 15:16:55 vnivanch Exp $ |
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27 | // GEANT4 tag $Name: geant4-09-03-ref-09 $ |
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28 | // |
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29 | // ------------------------------------------------------------------- |
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30 | // |
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31 | // GEANT4 Class file |
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32 | // |
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33 | // |
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34 | // File name: G4PreCompoundNeutron |
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35 | // |
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36 | // Author: V.Lara |
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37 | // |
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38 | // Modified: |
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39 | // 21.08.2008 J. M. Quesada add choice of options |
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40 | // 10.02.2009 J. M. Quesada set default opt3 |
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41 | // 20.08.2010 V.Ivanchenko added G4Pow and G4PreCompoundParameters pointers |
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42 | // use int Z and A and cleanup |
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43 | // |
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44 | |
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45 | #include "G4PreCompoundNeutron.hh" |
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46 | #include "G4Neutron.hh" |
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47 | |
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48 | G4PreCompoundNeutron::G4PreCompoundNeutron() |
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49 | : G4PreCompoundNucleon(G4Neutron::Neutron(), &theNeutronCoulombBarrier) |
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50 | {} |
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51 | |
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52 | G4PreCompoundNeutron::~G4PreCompoundNeutron() |
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53 | {} |
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54 | |
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55 | G4double G4PreCompoundNeutron::GetRj(G4int nParticles, G4int nCharged) |
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56 | { |
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57 | G4double rj = 0.0; |
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58 | if(nParticles > 0) { |
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59 | rj = static_cast<G4double>(nParticles - nCharged)/ |
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60 | static_cast<G4double>(nParticles); |
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61 | } |
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62 | return rj; |
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63 | } |
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64 | |
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65 | //////////////////////////////////////////////////////////////////////////////////// |
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66 | //J. M. Quesada (Dec 2007-June 2008): New inverse reaction cross sections |
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67 | //OPT=0 Dostrovski's parameterization |
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68 | //OPT=1,2 Chatterjee's paramaterization |
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69 | //OPT=3,4 Kalbach's parameterization |
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70 | // |
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71 | G4double G4PreCompoundNeutron::CrossSection(const G4double K) |
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72 | { |
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73 | ResidualA = GetRestA(); |
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74 | ResidualZ = GetRestZ(); |
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75 | theA = GetA(); |
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76 | theZ = GetZ(); |
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77 | ResidualAthrd = ResidualA13(); |
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78 | FragmentA = theA + ResidualA; |
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79 | FragmentAthrd = g4pow->Z13(FragmentA); |
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80 | |
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81 | if (OPTxs==0) { return GetOpt0( K); } |
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82 | else if( OPTxs==1 || OPTxs==2) { return GetOpt12( K); } |
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83 | else if (OPTxs==3 || OPTxs==4) { return GetOpt34( K); } |
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84 | else{ |
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85 | std::ostringstream errOs; |
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86 | errOs << "BAD NEUTRON CROSS SECTION OPTION !!" <<G4endl; |
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87 | throw G4HadronicException(__FILE__, __LINE__, errOs.str()); |
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88 | return 0.; |
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89 | } |
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90 | } |
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91 | |
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92 | G4double G4PreCompoundNeutron::GetAlpha() |
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93 | { |
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94 | return 0.76+2.2/ResidualAthrd; |
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95 | } |
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96 | |
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97 | G4double G4PreCompoundNeutron::GetBeta() |
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98 | { |
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99 | // return (2.12/std::pow(GetRestA(),2.0/3.0)-0.05)*MeV/GetAlpha(); |
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100 | return (2.12/(ResidualAthrd*ResidualAthrd)-0.05)*MeV/GetAlpha(); |
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101 | } |
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102 | |
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103 | //********************* OPT=1,2 : Chatterjee's cross section ******************* |
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104 | //(fitting to cross section from Bechetti & Greenles OM potential) |
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105 | |
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106 | G4double G4PreCompoundNeutron::GetOpt12(G4double K) |
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107 | { |
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108 | G4double Kc=K; |
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109 | |
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110 | // Pramana (Bechetti & Greenles) for neutrons is chosen |
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111 | |
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112 | // JMQ xsec is set constat above limit of validity |
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113 | if (K > 50*MeV) { Kc = 50*MeV; } |
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114 | |
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115 | G4double landa, landa0, landa1, mu, mu0, mu1,nu, nu0, nu1, nu2,xs; |
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116 | |
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117 | landa0 = 18.57; |
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118 | landa1 = -22.93; |
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119 | mu0 = 381.7; |
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120 | mu1 = 24.31; |
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121 | nu0 = 0.172; |
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122 | nu1 = -15.39; |
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123 | nu2 = 804.8; |
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124 | landa = landa0/ResidualAthrd + landa1; |
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125 | mu = mu0*ResidualAthrd + mu1*ResidualAthrd*ResidualAthrd; |
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126 | nu = nu0*ResidualAthrd*ResidualA + nu1*ResidualAthrd*ResidualAthrd + nu2 ; |
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127 | xs=landa*Kc + mu + nu/Kc; |
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128 | if (xs <= 0.0 ){ |
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129 | std::ostringstream errOs; |
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130 | G4cout<<"WARNING: NEGATIVE OPT=1 neutron cross section "<<G4endl; |
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131 | errOs << "RESIDUAL: Ar=" << ResidualA << " Zr=" << ResidualZ <<G4endl; |
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132 | errOs <<" xsec("<<Kc<<" MeV) ="<<xs <<G4endl; |
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133 | throw G4HadronicException(__FILE__, __LINE__, errOs.str()); |
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134 | } |
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135 | return xs; |
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136 | } |
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137 | |
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138 | // *********** OPT=3,4 : Kalbach's cross sections (from PRECO code)************* |
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139 | G4double G4PreCompoundNeutron::GetOpt34(G4double K) |
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140 | { |
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141 | G4double landa, landa0, landa1, mu, mu0, mu1,nu, nu0, nu1, nu2; |
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142 | G4double p, p0, p1, p2; |
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143 | G4double flow,spill,ec,ecsq,xnulam,etest(0.),ra(0.),a,signor(1.),sig; |
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144 | G4double b,ecut,cut,ecut2,geom,elab; |
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145 | |
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146 | //safety initialization |
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147 | landa0=0; |
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148 | landa1=0; |
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149 | mu0=0.; |
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150 | mu1=0.; |
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151 | nu0=0.; |
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152 | nu1=0.; |
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153 | nu2=0.; |
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154 | p0=0.; |
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155 | p1=0.; |
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156 | p2=0.; |
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157 | |
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158 | flow = 1.e-18; |
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159 | spill= 1.0e+18; |
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160 | |
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161 | // PRECO xs for neutrons is choosen |
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162 | p0 = -312.; |
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163 | p1= 0.; |
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164 | p2 = 0.; |
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165 | landa0 = 12.10; |
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166 | landa1= -11.27; |
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167 | mu0 = 234.1; |
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168 | mu1 = 38.26; |
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169 | nu0 = 1.55; |
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170 | nu1 = -106.1; |
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171 | nu2 = 1280.8; |
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172 | |
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173 | if (ResidualA < 40) { signor =0.7 + ResidualA*0.0075; } |
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174 | if (ResidualA > 210) { signor = 1. + (ResidualA-210)/250.; } |
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175 | landa = landa0/ResidualAthrd + landa1; |
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176 | mu = mu0*ResidualAthrd + mu1*ResidualAthrd*ResidualAthrd; |
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177 | nu = nu0*ResidualAthrd*ResidualA + nu1*ResidualAthrd*ResidualAthrd + nu2; |
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178 | |
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179 | // JMQ very low energy behaviour corrected (problem for A (apprx.)>60) |
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180 | if (nu < 0.) { nu=-nu; } |
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181 | |
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182 | ec = 0.5; |
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183 | ecsq = 0.25; |
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184 | p = p0; |
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185 | xnulam = 1.; |
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186 | etest = 32.; |
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187 | // ** etest is the energy above which the rxn cross section is |
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188 | // ** compared with the geometrical limit and the max taken. |
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189 | // ** xnulam here is a dummy value to be used later. |
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190 | |
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191 | a = -2.*p*ec + landa - nu/ecsq; |
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192 | b = p*ecsq + mu + 2.*nu/ec; |
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193 | ecut = 0.; |
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194 | cut = a*a - 4.*p*b; |
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195 | if (cut > 0.) { ecut = std::sqrt(cut); } |
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196 | ecut = (ecut-a) / (p+p); |
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197 | ecut2 = ecut; |
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198 | if (cut < 0.) { ecut2 = ecut - 2.; } |
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199 | elab = K * FragmentA / G4double(ResidualA); |
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200 | sig = 0.; |
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201 | if (elab <= ec) { //start for E<Ec |
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202 | if (elab > ecut2) { sig = (p*elab*elab+a*elab+b) * signor; } |
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203 | } //end for E<Ec |
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204 | else { //start for E>Ec |
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205 | sig = (landa*elab+mu+nu/elab) * signor; |
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206 | geom = 0.; |
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207 | if (xnulam < flow || elab < etest) { return sig; } |
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208 | geom = std::sqrt(theA*K); |
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209 | geom = 1.23*ResidualAthrd + ra + 4.573/geom; |
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210 | geom = 31.416 * geom * geom; |
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211 | sig = std::max(geom,sig); |
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212 | |
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213 | } |
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214 | return sig; |
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215 | } |
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