Gabriele Cosmo
103 lines
3.2 KiB
C++
103 lines
3.2 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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//
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// $Id: G4NeutronHPFissionSpectrum.hh,v 1.11 2006/06/29 20:47:57 gunter Exp $
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// GEANT4 tag $Name: geant4-09-01 $
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//
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#ifndef G4NeutronHPFissionSpectrum_h
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#define G4NeutronHPFissionSpectrum_h 1
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#include "globals.hh"
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#include "G4NeutronHPVector.hh"
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#include "Randomize.hh"
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#include "G4ios.hh"
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#include <fstream>
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#include "G4VNeutronHPEDis.hh"
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// we will need a List of these .... one per term.
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class G4NeutronHPFissionSpectrum : public G4VNeutronHPEDis
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{
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public:
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G4NeutronHPFissionSpectrum()
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{
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expm1 = std::exp(-1.);
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}
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~G4NeutronHPFissionSpectrum()
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{
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}
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inline void Init(std::ifstream & aDataFile)
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{
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theFractionalProb.Init(aDataFile, eV);
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theThetaDist.Init(aDataFile, eV);
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}
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inline G4double GetFractionalProbability(G4double anEnergy)
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{
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return theFractionalProb.GetY(anEnergy);
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}
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inline G4double Sample(G4double anEnergy)
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{
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G4double theta = theThetaDist.GetY(anEnergy);
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// here we need to sample Maxwells distribution, if
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// need be.
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G4double result, cut;
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G4double range =50*MeV;
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G4double max = Maxwell((theta*eV)/2., theta);
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G4double value;
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do
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{
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result = range*G4UniformRand();
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value = Maxwell(result, theta);
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cut = G4UniformRand();
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}
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while(cut > value/max);
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return result;
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}
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private:
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// this is the function to sample from.
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inline G4double Maxwell(G4double anEnergy, G4double theta)
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{
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G4double result = std::sqrt(anEnergy/eV)*std::exp(-anEnergy/eV/theta);
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return result;
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}
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private:
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G4double expm1;
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G4NeutronHPVector theFractionalProb;
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G4NeutronHPVector theThetaDist;
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};
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#endif
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