[819] | 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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| 26 | // |
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| 27 | // Class G4E1Probability.cc |
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| 28 | // |
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| 29 | |
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| 30 | #include "G4E1Probability.hh" |
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| 31 | #include "G4ConstantLevelDensityParameter.hh" |
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| 32 | #include "Randomize.hh" |
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| 33 | |
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| 34 | // Constructors and operators |
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| 35 | // |
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| 36 | |
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| 37 | G4E1Probability::G4E1Probability(const G4E1Probability& ) : G4VEmissionProbability() |
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| 38 | { |
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| 39 | |
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| 40 | throw G4HadronicException(__FILE__, __LINE__, "G4E1Probability::copy_constructor meant to not be accessible"); |
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| 41 | |
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| 42 | } |
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| 43 | |
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| 44 | const G4E1Probability& G4E1Probability:: |
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| 45 | operator=(const G4E1Probability& ) |
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| 46 | { |
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| 47 | |
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| 48 | throw G4HadronicException(__FILE__, __LINE__, "G4E1Probability::operator= meant to not be accessible"); |
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| 49 | return *this; |
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| 50 | } |
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| 51 | |
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| 52 | G4bool G4E1Probability::operator==(const G4E1Probability& ) const |
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| 53 | { |
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| 54 | |
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| 55 | return false; |
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| 56 | |
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| 57 | } |
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| 58 | |
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| 59 | G4bool G4E1Probability::operator!=(const G4E1Probability& ) const |
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| 60 | { |
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| 61 | |
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| 62 | return true; |
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| 63 | |
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| 64 | } |
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| 65 | |
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| 66 | // Calculate the emission probability |
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| 67 | // |
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| 68 | |
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| 69 | G4double G4E1Probability::EmissionProbDensity(const G4Fragment& frag, |
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| 70 | const G4double gammaE) |
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| 71 | { |
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| 72 | |
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| 73 | // Calculate the probability density here |
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| 74 | |
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| 75 | // From nuclear fragment properties and the excitation energy, calculate |
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| 76 | // the probability density for photon evaporation from U to U - gammaE |
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| 77 | // (U = nucleus excitation energy, gammaE = total evaporated photon |
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| 78 | // energy). |
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| 79 | // fragment = nuclear fragment BEFORE de-excitation |
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| 80 | |
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| 81 | G4double theProb = 0.0; |
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| 82 | |
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| 83 | const G4double Afrag = frag.GetA(); |
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| 84 | const G4double Zfrag = frag.GetZ(); |
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| 85 | const G4double Uexcite = frag.GetExcitationEnergy(); |
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| 86 | |
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| 87 | if( (Uexcite-gammaE) < 0.0 || gammaE < 0 || Uexcite <= 0) return theProb; |
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| 88 | |
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| 89 | // Need a level density parameter. |
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| 90 | // For now, just use the constant approximation (not reliable near magic |
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| 91 | // nuclei). |
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| 92 | |
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| 93 | static G4ConstantLevelDensityParameter a; |
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| 94 | |
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| 95 | G4double aLevelDensityParam = a.LevelDensityParameter(static_cast<G4int>(Afrag), |
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| 96 | static_cast<G4int>(Zfrag), |
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| 97 | Uexcite); |
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| 98 | |
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| 99 | G4double levelDensBef = std::exp(2.0*std::sqrt(aLevelDensityParam*Uexcite)); |
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| 100 | G4double levelDensAft = std::exp(2.0*std::sqrt(aLevelDensityParam*(Uexcite-gammaE))); |
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| 101 | |
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| 102 | // Now form the probability density |
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| 103 | |
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| 104 | // Define constants for the photoabsorption cross-section (the reverse |
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| 105 | // process of our de-excitation) |
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| 106 | |
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| 107 | G4double sigma0 = 2.5 * Afrag * millibarn; // millibarns |
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| 108 | |
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| 109 | G4double Egdp = (40.3 / std::pow(Afrag,0.2) )*MeV; |
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| 110 | G4double GammaR = 0.30 * Egdp; |
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| 111 | |
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| 112 | static G4double normC = 1.0 / ((pi * hbarc)*(pi * hbarc)); |
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| 113 | |
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| 114 | // CD |
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| 115 | //cout<<" PROB TESTS "<<G4endl; |
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| 116 | //cout<<" hbarc = "<<hbarc<<G4endl; |
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| 117 | //cout<<" pi = "<<pi<<G4endl; |
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| 118 | //cout<<" Uexcite, gammaE = "<<Uexcite<<" "<<gammaE<<G4endl; |
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| 119 | //cout<<" Uexcite, gammaE = "<<Uexcite*MeV<<" "<<gammaE*MeV<<G4endl; |
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| 120 | //cout<<" lev density param = "<<aLevelDensityParam<<G4endl; |
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| 121 | //cout<<" level densities = "<<levelDensBef<<" "<<levelDensAft<<G4endl; |
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| 122 | //cout<<" sigma0 = "<<sigma0<<G4endl; |
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| 123 | //cout<<" Egdp, GammaR = "<<Egdp<<" "<<GammaR<<G4endl; |
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| 124 | //cout<<" normC = "<<normC<<G4endl; |
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| 125 | |
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| 126 | G4double numerator = sigma0 * gammaE*gammaE * GammaR*GammaR; |
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| 127 | G4double denominator = (gammaE*gammaE - Egdp*Egdp)* |
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| 128 | (gammaE*gammaE - Egdp*Egdp) + GammaR*GammaR*gammaE*gammaE; |
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| 129 | |
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| 130 | G4double sigmaAbs = numerator/denominator; |
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| 131 | |
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| 132 | theProb = normC * sigmaAbs * gammaE*gammaE * |
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| 133 | levelDensAft/levelDensBef; |
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| 134 | |
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| 135 | // CD |
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| 136 | //cout<<" sigmaAbs = "<<sigmaAbs<<G4endl; |
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| 137 | //cout<<" Probability = "<<theProb<<G4endl; |
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| 138 | |
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| 139 | return theProb; |
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| 140 | |
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| 141 | } |
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| 142 | |
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| 143 | G4double G4E1Probability::EmissionProbability(const G4Fragment& frag, |
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| 144 | const G4double gammaE) |
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| 145 | { |
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| 146 | |
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| 147 | // From nuclear fragment properties and the excitation energy, calculate |
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| 148 | // the probability for photon evaporation down to last ground level. |
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| 149 | // fragment = nuclear fragment BEFORE de-excitation |
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| 150 | |
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| 151 | G4double theProb = 0.0; |
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| 152 | |
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| 153 | G4double Uafter = 0.0; |
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| 154 | const G4double Uexcite = frag.GetExcitationEnergy(); |
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| 155 | |
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| 156 | G4double normC = 3.0; |
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| 157 | |
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| 158 | const G4double upperLim = Uexcite; |
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| 159 | const G4double lowerLim = Uafter; |
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| 160 | const G4int numIters = 100; |
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| 161 | |
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| 162 | // Fall-back is a uniform random number |
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| 163 | |
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| 164 | //G4double uniformNum = G4UniformRand(); |
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| 165 | //theProb = uniformNum; |
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| 166 | |
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| 167 | // Need to integrate EmissionProbDensity from lowerLim to upperLim |
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| 168 | // and multiply by normC |
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| 169 | |
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| 170 | G4double integ = normC * |
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| 171 | EmissionIntegration(frag,gammaE,lowerLim,upperLim,numIters); |
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| 172 | if(integ > 0.0) theProb = integ/(upperLim-lowerLim); |
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| 173 | |
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| 174 | return theProb; |
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| 175 | |
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| 176 | } |
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| 177 | |
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| 178 | G4double G4E1Probability::EmissionIntegration(const G4Fragment& frag, |
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| 179 | const G4double , |
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| 180 | const G4double lowLim, const G4double upLim, |
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| 181 | const G4int numIters) |
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| 182 | |
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| 183 | { |
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| 184 | |
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| 185 | // Simple Gaussian quadrature integration |
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| 186 | |
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| 187 | G4double x; |
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| 188 | G4double root3 = 1.0/std::sqrt(3.0); |
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| 189 | |
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| 190 | G4double Step = (upLim-lowLim)/(2.0*numIters); |
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| 191 | G4double Delta = Step*root3; |
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| 192 | |
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| 193 | G4double mean = 0.0; |
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| 194 | |
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| 195 | G4double theInt = 0.0; |
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| 196 | |
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| 197 | for(G4int i = 0; i < numIters; i++) { |
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| 198 | |
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| 199 | x = (2*i + 1)*Step; |
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| 200 | G4double E1ProbDensityA = EmissionProbDensity(frag,x+Delta); |
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| 201 | G4double E1ProbDensityB = EmissionProbDensity(frag,x-Delta); |
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| 202 | |
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| 203 | mean += E1ProbDensityA + E1ProbDensityB; |
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| 204 | |
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| 205 | } |
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| 206 | |
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| 207 | if(mean*Step > 0.0) theInt = mean*Step; |
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| 208 | |
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| 209 | return theInt; |
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| 210 | |
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| 211 | } |
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| 212 | |
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| 213 | G4E1Probability::~G4E1Probability() {} |
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| 214 | |
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| 215 | |
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