[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 | // Implementation of the HETC88 code into Geant4. |
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| 28 | // Evaporation and De-excitation parts |
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| 29 | // T. Lampen, Helsinki Institute of Physics, May-2000 |
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| 30 | |
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| 31 | #include "globals.hh" |
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| 32 | #include "G4ios.hh" |
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| 33 | #include "Randomize.hh" |
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| 34 | #include "G4Neutron.hh" |
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| 35 | #include "G4Proton.hh" |
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| 36 | #include "G4Deuteron.hh" |
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| 37 | #include "G4Triton.hh" |
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| 38 | #include "G4Alpha.hh" |
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| 39 | #include "G4ParticleTable.hh" |
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| 40 | #include "G4Nucleus.hh" |
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| 41 | #include "G4BENeutronChannel.hh" |
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| 42 | |
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| 43 | |
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| 44 | G4BENeutronChannel::G4BENeutronChannel() |
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| 45 | { |
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| 46 | name = "neutron"; |
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| 47 | particleA = 1; |
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| 48 | particleZ = 0; |
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| 49 | verboseLevel = 0; |
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| 50 | rho = 0; |
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| 51 | } |
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| 52 | |
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| 53 | |
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| 54 | G4BENeutronChannel::~G4BENeutronChannel() |
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| 55 | { |
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| 56 | } |
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| 57 | |
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| 58 | |
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| 59 | void G4BENeutronChannel::calculateProbability() |
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| 60 | { |
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| 61 | const G4int residualZ = nucleusZ - particleZ; |
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| 62 | const G4int residualA = nucleusA - particleA; |
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| 63 | |
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| 64 | if ( nucleusA < 2.0 * particleA || |
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| 65 | nucleusZ < 2.0 * particleZ || |
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| 66 | residualA <= residualZ || |
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| 67 | excitationEnergy - getThresh() - correction < 0 ) |
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| 68 | { |
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| 69 | if ( verboseLevel >= 6 ) |
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| 70 | G4cout << "G4BENeutronChannel : calculateProbability = 0 " << G4endl; |
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| 71 | emissionProbability = 0; |
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| 72 | return; |
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| 73 | } |
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| 74 | |
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| 75 | // In HETC88 s-s0 was used in std::exp( s ), in which s0 was either 50 or |
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| 76 | // max(s_i), where i goes over all channels. |
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| 77 | |
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| 78 | const G4double levelParam = getLevelDensityParameter(); |
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| 79 | |
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| 80 | const G4double s = 2 * std::sqrt( levelParam * ( excitationEnergy - getThresh() - correction ) ); |
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| 81 | // const G4double temp = ( std::pow( s, 2. ) - 3 * s + 3 ) / ( 4 * std::pow( levelParam, 2. ) ) |
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| 82 | // + beta() * ( s - 1 ) / ( 2 * levelParam ); |
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| 83 | const G4double eye0 = std::exp( s ) * ( s - 1 ) / ( 2 * levelParam ); |
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| 84 | const G4double eye1 = ( std::pow( s, 2. ) - 3*s +3 ) * std::exp( s ) / ( 4 * std::pow( levelParam, 2. ) ) ; |
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| 85 | |
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| 86 | emissionProbability = std::pow( G4double(residualA), 0.666666 ) * alpha() * ( eye1 + beta() * eye0 ); |
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| 87 | |
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| 88 | if ( verboseLevel >= 6 ) |
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| 89 | G4cout << "G4BENeutronChannel : calculateProbability " << G4endl |
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| 90 | << " res A = " << residualA << G4endl |
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| 91 | << " res Z = " << residualZ << G4endl |
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| 92 | << " alpha = " << alpha() << G4endl |
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| 93 | << " beta = " << beta() << G4endl |
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| 94 | << " E = " << excitationEnergy << G4endl |
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| 95 | << " correction = " << correction << G4endl |
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| 96 | << " eye1 = " << eye1 << G4endl |
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| 97 | << " eye0 = " << eye0 << G4endl |
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| 98 | << " levelParam = " << levelParam << G4endl |
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| 99 | << " thresh = " << getThresh() << G4endl |
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| 100 | << " s = " << s << G4endl |
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| 101 | << " probability = " << emissionProbability << G4endl; |
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| 102 | |
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| 103 | return; |
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| 104 | } |
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| 105 | |
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| 106 | |
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| 107 | G4double G4BENeutronChannel::sampleKineticEnergy() |
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| 108 | { |
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| 109 | // Samples the kinetic energy of the particle in CMS |
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| 110 | // |
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| 111 | // Algorithm used in HETC98 |
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| 112 | // |
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| 113 | // G4double e1; |
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| 114 | // G4double e2; |
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| 115 | // G4double s; |
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| 116 | // G4double levelParam; |
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| 117 | // G4double eye0; |
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| 118 | // G4double eye1; |
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| 119 | // G4double kineticEnergyAv; |
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| 120 | // G4double kineticEnergy; |
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| 121 | |
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| 122 | // e1 = RandExponential::shoot( 1 ); |
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| 123 | // e2 = RandExponential::shoot( 1 ); |
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| 124 | |
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| 125 | // levelParam = getLevelDensityParameter(); |
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| 126 | // s = 2 * std::sqrt( levelParam * ( excitationEnergy - getThresh() - correction ) ); |
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| 127 | // eye0 = 0.5 * ( s - 1 ) * std::exp( s ) / levelParam; |
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| 128 | // eye1 = ( std::pow( s, 2. ) - 3*s + 3 ) * std::exp( s ) / ( 4 * std::pow( levelParam, 2. ) ); |
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| 129 | // kineticEnergyAv = 2 * ( std::pow( s, 3. ) - 6.0 * std::pow( s, 2. ) + 15.0 * s - 15.0 ) / |
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| 130 | // ( ( 2.0 * std::pow( s, 2. ) - 6.0 * s + 6.0 ) * levelParam ); |
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| 131 | // kineticEnergyAv = ( kineticEnergyAv + beta() ) / ( 1.0 + beta() * eye0 |
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| 132 | // / eye1 ); |
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| 133 | |
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| 134 | // kineticEnergy = 0.5 * ( e1 + e2 ) * kineticEnergyAv + getThresh() - getQ(); |
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| 135 | |
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| 136 | //////////////// |
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| 137 | // A random number is sampled from the density function |
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| 138 | // P(x) = x * std::exp ( 2 std::sqrt ( a ( xMax - x ) ) ) [not normalized], |
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| 139 | // x belongs to [ 0, xMax ] |
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| 140 | // with the 'Hit or Miss' -method |
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| 141 | // Kinetic energy is this energy scaled properly |
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| 142 | |
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| 143 | G4double levelParam; |
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| 144 | levelParam = getLevelDensityParameter(); |
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| 145 | |
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| 146 | const G4double xMax = excitationEnergy - getThresh() - correction + beta(); // maximum number |
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| 147 | const G4double xProb = ( - 1 + std::sqrt ( 1 + 4 * levelParam * xMax ) ) / ( 2 * levelParam ); // most probable value |
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| 148 | const G4double m = xProb * std::exp ( 2 * std::sqrt ( levelParam * ( xMax - xProb ) ) ); // maximum value of P(x) |
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| 149 | |
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| 150 | // Sample x according to density function P(x) with rejection method |
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| 151 | G4double r1; |
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| 152 | G4double r2; |
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| 153 | G4int koe=0; |
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| 154 | do |
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| 155 | { |
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| 156 | r1 = beta() + G4UniformRand() * ( xMax - beta() ); |
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| 157 | r2 = G4UniformRand() * m; |
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| 158 | koe++; |
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| 159 | } |
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| 160 | while ( r1 * std::exp ( 2 * std::sqrt ( levelParam * ( xMax - r1 ) ) ) < r2 ); |
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| 161 | |
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| 162 | // G4cout << koe << G4endl; |
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| 163 | G4double kineticEnergy = r1 - beta(); |
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| 164 | |
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| 165 | if ( verboseLevel >= 10 ) |
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| 166 | G4cout << " G4BENeutronChannel : sampleKineticEnergy() " << G4endl |
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| 167 | << " kinetic n e = " << kineticEnergy << G4endl |
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| 168 | << " levelParam = " << levelParam << G4endl |
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| 169 | << " thresh= " << getThresh() << G4endl |
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| 170 | << " beta= " << beta() << G4endl; |
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| 171 | |
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| 172 | return kineticEnergy; |
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| 173 | } |
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| 174 | |
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| 175 | |
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| 176 | G4DynamicParticle * G4BENeutronChannel::emit() |
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| 177 | { |
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| 178 | G4double u; |
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| 179 | G4double v; |
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| 180 | G4double w; |
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| 181 | G4DynamicParticle * pParticle = new G4DynamicParticle; |
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| 182 | |
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| 183 | pParticle -> SetDefinition( G4Neutron::Neutron() ); |
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| 184 | pParticle -> SetKineticEnergy( sampleKineticEnergy() ); |
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| 185 | isotropicCosines( u, v, w ); |
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| 186 | pParticle -> SetMomentumDirection( u , v , w ); |
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| 187 | |
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| 188 | return pParticle; |
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| 189 | } |
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| 190 | |
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| 191 | |
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| 192 | G4double G4BENeutronChannel::alpha() |
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| 193 | { |
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| 194 | const G4double residualA = nucleusA - particleA; |
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| 195 | return 0.76 + 1.93 * std::pow( residualA, -0.33333 ); |
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| 196 | } |
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| 197 | |
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| 198 | |
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| 199 | G4double G4BENeutronChannel::beta() |
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| 200 | { |
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| 201 | G4double residualA = nucleusA - particleA; |
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| 202 | return ( 1.66 * std::pow ( residualA, -0.66666 ) - 0.05 )/alpha()*MeV; |
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| 203 | } |
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| 204 | |
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