[968] | 1 | // |
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| 2 | // ******************************************************************** |
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| 3 | // * License and Disclaimer * |
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| 4 | // * * |
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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| 7 | // * conditions of the Geant4 Software License, included in the file * |
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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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[1340] | 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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[968] | 28 | // |
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[1055] | 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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[1340] | 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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[968] | 43 | // |
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[1055] | 44 | |
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[968] | 45 | #include "G4PreCompoundNeutron.hh" |
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[1340] | 46 | #include "G4Neutron.hh" |
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[968] | 47 | |
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[1340] | 48 | G4PreCompoundNeutron::G4PreCompoundNeutron() |
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| 49 | : G4PreCompoundNucleon(G4Neutron::Neutron(), &theNeutronCoulombBarrier) |
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| 50 | {} |
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[968] | 51 | |
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[1340] | 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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[1055] | 56 | { |
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| 57 | G4double rj = 0.0; |
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[1340] | 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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[1055] | 62 | return rj; |
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| 63 | } |
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[968] | 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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[1055] | 71 | G4double G4PreCompoundNeutron::CrossSection(const G4double K) |
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[968] | 72 | { |
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[1340] | 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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[968] | 80 | |
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[1340] | 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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[968] | 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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[1055] | 92 | G4double G4PreCompoundNeutron::GetAlpha() |
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| 93 | { |
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[968] | 94 | return 0.76+2.2/ResidualAthrd; |
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[1055] | 95 | } |
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[1340] | 96 | |
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[1055] | 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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[968] | 102 | |
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[1340] | 103 | //********************* OPT=1,2 : Chatterjee's cross section ******************* |
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[968] | 104 | //(fitting to cross section from Bechetti & Greenles OM potential) |
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| 105 | |
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[1340] | 106 | G4double G4PreCompoundNeutron::GetOpt12(G4double K) |
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[968] | 107 | { |
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| 108 | G4double Kc=K; |
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| 109 | |
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[1340] | 110 | // Pramana (Bechetti & Greenles) for neutrons is chosen |
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[968] | 111 | |
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[1340] | 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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[968] | 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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[1340] | 139 | G4double G4PreCompoundNeutron::GetOpt34(G4double K) |
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[968] | 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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[1055] | 146 | //safety initialization |
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[968] | 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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[1055] | 161 | // PRECO xs for neutrons is choosen |
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[968] | 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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[1340] | 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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[968] | 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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[1340] | 180 | if (nu < 0.) { nu=-nu; } |
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[968] | 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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[1055] | 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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[968] | 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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[1340] | 195 | if (cut > 0.) { ecut = std::sqrt(cut); } |
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[968] | 196 | ecut = (ecut-a) / (p+p); |
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| 197 | ecut2 = ecut; |
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[1340] | 198 | if (cut < 0.) { ecut2 = ecut - 2.; } |
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| 199 | elab = K * FragmentA / G4double(ResidualA); |
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[968] | 200 | sig = 0.; |
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| 201 | if (elab <= ec) { //start for E<Ec |
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[1340] | 202 | if (elab > ecut2) { sig = (p*elab*elab+a*elab+b) * signor; } |
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[968] | 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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[1340] | 207 | if (xnulam < flow || elab < etest) { return sig; } |
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[968] | 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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[1340] | 214 | return sig; |
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| 215 | } |
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