include/Geant4/G4HadPhaseSpaceGenbod.hh

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0025 //
0026 //
0027 // Multibody "phase space" generator using GENBOD (CERNLIB W515) method.
0028 //
0029 // Author:  Michael Kelsey (SLAC) <kelsey@slac.stanford.edu>
0030
0031 #ifndef G4HadPhaseSpaceGenbod_HH
0032 #define G4HadPhaseSpaceGenbod_HH 1
0033
0034 #include "G4VHadPhaseSpaceAlgorithm.hh"
0035
0036
0037 class G4HadPhaseSpaceGenbod : public G4VHadPhaseSpaceAlgorithm {
0038 public:
0039   G4HadPhaseSpaceGenbod(G4int verbose=0);
0040   virtual ~G4HadPhaseSpaceGenbod() {;}
0041
0042 protected:
0043   virtual void GenerateMultiBody(G4double initialMass,
0044                  const std::vector<G4double>& masses,
0045                  std::vector<G4LorentzVector>& finalState);
0046
0047 protected:
0048   void Initialize(G4double initialMass,
0049           const std::vector<G4double>& masses);
0050
0051   void FillRandomBuffer();
0052
0053   void ComputeWeightScale(const std::vector<G4double>& masses);
0054
0055   void FillEnergySteps(G4double initialMass,
0056                const std::vector<G4double>& masses);
0057
0058   void GenerateMomenta(const std::vector<G4double>& masses,
0059                std::vector<G4LorentzVector>& finalState);
0060
0061   void AccumulateFinalState(size_t i,
0062                 const std::vector<G4double>& masses,
0063                 std::vector<G4LorentzVector>& finalState);
0064
0065   G4bool AcceptEvent() const;   // Use accept-reject to generate distribution
0066   G4double ComputeWeight() const;
0067
0068 private:
0069   size_t nFinal;        // Number of final state particles
0070   G4double totalMass;       // Sum of final state masses
0071   G4double massExcess;      // Available kinetic energy
0072   G4double weightMax;       // Maximum possible weight
0073   G4int nTrials;        // Accept/reject cycles taken
0074
0075   std::vector<G4double> msum;   // Cumulative sum of masses
0076   std::vector<G4double> msq;    // Final state squared masses
0077   std::vector<G4double> rndm;   // Random sequence for effective masses
0078   std::vector<G4double> meff;   // Random final-state effective masses
0079   std::vector<G4double> pd; // Random momentum magnitudes
0080 };
0081
0082 #endif  /* G4HadPhaseSpaceGenbod_HH */