Gabriele Cosmo
153 lines
4.8 KiB
C++
153 lines
4.8 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: G4NeutronHPMadlandNixSpectrum.hh,v 1.12 2006/06/29 20:48:33 gunter Exp $
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// GEANT4 tag $Name: geant4-09-01 $
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//
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#ifndef G4NeutronHPMadlandNixSpectrum_h
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#define G4NeutronHPMadlandNixSpectrum_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 <cmath>
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#include "G4VNeutronHPEDis.hh"
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// #include <nag.h> @
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// #include <nags.h> @
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// we will need a List of these .... one per term.
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class G4NeutronHPMadlandNixSpectrum : public G4VNeutronHPEDis
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{
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public:
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G4NeutronHPMadlandNixSpectrum()
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{
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expm1 = std::exp(-1.);
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}
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~G4NeutronHPMadlandNixSpectrum()
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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);
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aDataFile>> theAvarageKineticPerNucleonForLightFragments;
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theAvarageKineticPerNucleonForLightFragments*=eV;
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aDataFile>> theAvarageKineticPerNucleonForHeavyFragments;
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theAvarageKineticPerNucleonForHeavyFragments*=eV;
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theMaxTemp.Init(aDataFile);
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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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G4double Sample(G4double anEnergy);
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private:
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G4double Madland(G4double aSecEnergy, G4double tm);
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inline G4double FissionIntegral(G4double tm, G4double anEnergy)
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{
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return 0.5*( GIntegral(tm, anEnergy, theAvarageKineticPerNucleonForLightFragments)
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+GIntegral(tm, anEnergy, theAvarageKineticPerNucleonForHeavyFragments) );
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}
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G4double GIntegral(G4double tm, G4double anEnergy, G4double aMean);
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inline G4double Gamma05(G4double aValue)
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{
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G4double result;
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// gamma(1.2,x*X) = std::sqrt(pi)*Erf(x)
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G4double x = std::sqrt(aValue);
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G4double t = 1./(1+0.47047*x);
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result = 1- (0.3480242*t - 0.0958798*t*t + 0.7478556*t*t*t)*std::exp(-aValue); // @ check
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result *= std::sqrt(pi);
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return result;
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}
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inline G4double Gamma15(G4double aValue)
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{
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G4double result;
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// gamma(a+1, x) = a*gamma(a,x)-x**a*std::exp(-x)
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result = 0.5*Gamma05(aValue) - std::sqrt(aValue)*std::exp(-aValue); // @ check
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return result;
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}
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inline G4double Gamma25(G4double aValue)
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{
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G4double result;
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result = 1.5*Gamma15(aValue) - std::pow(aValue,1.5)*std::exp(aValue); // @ check
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return result;
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}
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inline G4double E1(G4double aValue)
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{
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// good only for rather low aValue @@@ replace by the corresponding NAG function for the
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// exponential integral. (<5 seems ok.
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G4double gamma = 0.577216;
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G4double precision = 0.000001;
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G4double result =-gamma - std::log(aValue);
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G4double term = -aValue;
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G4double last;
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G4int count = 1;
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result -= term;
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for(;;)
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{
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count++;
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last = result;
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term = -term*aValue*(count-1)/(count*count);
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result -=term;
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if(std::fabs(term)/std::fabs(result)<precision) break;
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}
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// NagError *fail; @
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// result = nag_exp_integral(aValue, fail); @
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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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private:
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G4NeutronHPVector theFractionalProb;
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G4double theAvarageKineticPerNucleonForLightFragments;
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G4double theAvarageKineticPerNucleonForHeavyFragments;
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G4NeutronHPVector theMaxTemp;
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};
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#endif
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