include/Geant4/G4ParticleHPSimpleEvapSpectrum.hh

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0025 //
0026 //
0027 // P. Arce, June-2014 Conversion neutron_hp to particle_hp
0028 //
0029 #ifndef G4ParticleHPSimpleEvapSpectrum_h
0030 #define G4ParticleHPSimpleEvapSpectrum_h 1
0031
0032 #include "G4Exp.hh"
0033 #include "G4Log.hh"
0034 #include "G4ParticleHPVector.hh"
0035 #include "G4VParticleHPEDis.hh"
0036 #include "G4ios.hh"
0037 #include "Randomize.hh"
0038 #include "globals.hh"
0039
0040 #include <CLHEP/Units/SystemOfUnits.h>
0041
0042 #include <fstream>
0043
0044 // we will need a List of these .... one per term.
0045
0046 class G4ParticleHPSimpleEvapSpectrum : public G4VParticleHPEDis
0047 {
0048   public:
0049     G4ParticleHPSimpleEvapSpectrum() { expm1 = G4Exp(-1.); }
0050     ~G4ParticleHPSimpleEvapSpectrum() override = default;
0051
0052     inline void Init(std::istream& aDataFile) override
0053     {
0054       theFractionalProb.Init(aDataFile, CLHEP::eV);
0055       theThetaDist.Init(aDataFile, CLHEP::eV);
0056     }
0057
0058     inline G4double GetFractionalProbability(G4double anEnergy) override
0059     {
0060       return theFractionalProb.GetY(anEnergy);
0061     }
0062
0063     inline G4double Sample(G4double anEnergy) override
0064     {
0065       G4double theta = theThetaDist.GetY(anEnergy) * CLHEP::eV;
0066       G4double random, cut, max, result = 0.;
0067       max = 10. * theta;
0068       G4int icounter = 0;
0069       G4int icounter_max = 1024;
0070       do {
0071         icounter++;
0072         if (icounter > icounter_max) {
0073           G4cout << "Loop-counter exceeded the threshold value at " << __LINE__ << "th line of "
0074                  << __FILE__ << "." << G4endl;
0075           break;
0076         }
0077         random = G4UniformRand();
0078         result = -theta * G4Log(random);
0079         cut = G4UniformRand();
0080       } while (cut > result / max);  // Loop checking, 11.05.2015, T. Koi
0081       return result;
0082     }
0083
0084   private:
0085     inline G4double Evapo(G4double anEnergy, G4double theta)
0086     {
0087       G4double result = (anEnergy * CLHEP::eV) * G4Exp(-anEnergy * CLHEP::eV / theta);
0088       return result;
0089     }
0090
0091   private:
0092     G4double expm1;
0093
0094     G4ParticleHPVector theFractionalProb;
0095
0096     G4ParticleHPVector theThetaDist;
0097 };
0098
0099 #endif