Geant4_10
G4NeutronHPFissionSpectrum.hh
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28 #ifndef G4NeutronHPFissionSpectrum_h
29 #define G4NeutronHPFissionSpectrum_h 1
30 
31 #include <fstream>
33 
34 #include "globals.hh"
35 #include "G4ios.hh"
36 #include "Randomize.hh"
37 #include "G4NeutronHPVector.hh"
38 #include "G4VNeutronHPEDis.hh"
39 
40 // we will need a List of these .... one per term.
41 
43 {
44  public:
46  {
47  expm1 = std::exp(-1.);
48  }
50  {
51  }
52 
53  inline void Init(std::istream & aDataFile)
54  {
55  theFractionalProb.Init(aDataFile, CLHEP::eV);
56  theThetaDist.Init(aDataFile, CLHEP::eV);
57  }
58 
60  {
61  return theFractionalProb.GetY(anEnergy);
62  }
63 
64  inline G4double Sample(G4double anEnergy)
65  {
66  G4double theta = theThetaDist.GetY(anEnergy);
67  // here we need to sample Maxwells distribution, if
68  // need be.
69  G4double result, cut;
70  G4double range =50*CLHEP::MeV;
71  G4double max = Maxwell((theta*CLHEP::eV)/2., theta);
73  do
74  {
75  result = range*G4UniformRand();
76  value = Maxwell(result, theta);
77  cut = G4UniformRand();
78  }
79  while(cut > value/max);
80  return result;
81  }
82 
83  private:
84 
85  // this is the function to sample from.
86  inline G4double Maxwell(G4double anEnergy, G4double theta)
87  {
88  G4double result = std::sqrt(anEnergy/CLHEP::eV)*std::exp(-anEnergy/CLHEP::eV/theta);
89  return result;
90  }
91 
92  private:
93 
94  G4double expm1;
95 
96  G4NeutronHPVector theFractionalProb;
97 
98  G4NeutronHPVector theThetaDist;
99 
100 };
101 
102 #endif
G4double GetY(G4double x)
G4double Sample(G4double anEnergy)
G4double G4NeutronHPJENDLHEData::G4double result
void Init(std::istream &aDataFile, G4int total, G4double ux=1., G4double uy=1.)
#define G4UniformRand()
Definition: Randomize.hh:87
const G4ParticleDefinition const G4Material *G4double range
T max(const T t1, const T t2)
brief Return the largest of the two arguments
void Init(std::istream &aDataFile)
const XML_Char int const XML_Char * value
Definition: expat.h:331
double G4double
Definition: G4Types.hh:76
G4double GetFractionalProbability(G4double anEnergy)