| 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 | // $Id: G4NeutronHPFissionSpectrum.hh,v 1.11 2006/06/29 20:47:57 gunter Exp $
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| 28 | // GEANT4 tag $Name: geant4-09-03-cand-01 $
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| 29 | //
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| 30 | #ifndef G4NeutronHPFissionSpectrum_h
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| 31 | #define G4NeutronHPFissionSpectrum_h 1
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| 32 |
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| 33 | #include "globals.hh"
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| 34 | #include "G4NeutronHPVector.hh"
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| 35 | #include "Randomize.hh"
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| 36 | #include "G4ios.hh"
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| 37 | #include <fstream>
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| 38 | #include "G4VNeutronHPEDis.hh"
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| 39 |
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| 40 | // we will need a List of these .... one per term.
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| 41 |
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| 42 | class G4NeutronHPFissionSpectrum : public G4VNeutronHPEDis
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| 43 | {
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| 44 | public:
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| 45 | G4NeutronHPFissionSpectrum()
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| 46 | {
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| 47 | expm1 = std::exp(-1.);
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| 48 | }
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| 49 | ~G4NeutronHPFissionSpectrum()
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| 50 | {
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| 51 | }
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| 52 |
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| 53 | inline void Init(std::ifstream & aDataFile)
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| 54 | {
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| 55 | theFractionalProb.Init(aDataFile, eV);
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| 56 | theThetaDist.Init(aDataFile, eV);
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| 57 | }
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| 58 |
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| 59 | inline G4double GetFractionalProbability(G4double anEnergy)
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| 60 | {
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| 61 | return theFractionalProb.GetY(anEnergy);
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| 62 | }
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| 63 |
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| 64 | inline G4double Sample(G4double anEnergy)
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| 65 | {
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| 66 | G4double theta = theThetaDist.GetY(anEnergy);
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| 67 | // here we need to sample Maxwells distribution, if
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| 68 | // need be.
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| 69 | G4double result, cut;
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| 70 | G4double range =50*MeV;
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| 71 | G4double max = Maxwell((theta*eV)/2., theta);
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| 72 | G4double value;
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| 73 | do
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| 74 | {
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| 75 | result = range*G4UniformRand();
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| 76 | value = Maxwell(result, theta);
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| 77 | cut = G4UniformRand();
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| 78 | }
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| 79 | while(cut > value/max);
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| 80 | return result;
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| 81 | }
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| 82 |
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| 83 | private:
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| 84 |
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| 85 | // this is the function to sample from.
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| 86 | inline G4double Maxwell(G4double anEnergy, G4double theta)
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| 87 | {
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| 88 | G4double result = std::sqrt(anEnergy/eV)*std::exp(-anEnergy/eV/theta);
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| 89 | return result;
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| 90 | }
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| 91 |
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| 92 | private:
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| 93 |
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| 94 | G4double expm1;
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| 95 |
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| 96 | G4NeutronHPVector theFractionalProb;
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| 97 |
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| 98 | G4NeutronHPVector theThetaDist;
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| 99 |
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| 100 | };
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| 101 |
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| 102 | #endif
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