G4HadPhaseSpaceGenbod.hh

Go to the documentation of this file.

//
// ********************************************************************
// * License and Disclaimer                                           *
// *                                                                  *
// * The  Geant4 software  is  copyright of the Copyright Holders  of *
// * the Geant4 Collaboration.  It is provided  under  the terms  and *
// * conditions of the Geant4 Software License,  included in the file *
// * LICENSE and available at  http://cern.ch/geant4/license .  These *
// * include a list of copyright holders.                             *
// *                                                                  *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work  make  any representation or  warranty, express or implied, *
// * regarding  this  software system or assume any liability for its *
// * use.  Please see the license in the file  LICENSE  and URL above *
// * for the full disclaimer and the limitation of liability.         *
// *                                                                  *
// * This  code  implementation is the result of  the  scientific and *
// * technical work of the GEANT4 collaboration.                      *
// * By using,  copying,  modifying or  distributing the software (or *
// * any work based  on the software)  you  agree  to acknowledge its *
// * use  in  resulting  scientific  publications,  and indicate your *
// * acceptance of all terms of the Geant4 Software license.          *
// ********************************************************************
//
//
// Multibody "phase space" generator using GENBOD (CERNLIB W515) method.
//
// Author:  Michael Kelsey (SLAC) <[email protected]>
 
#ifndef G4HadPhaseSpaceGenbod_HH
#define G4HadPhaseSpaceGenbod_HH 1
 
#include "G4VHadPhaseSpaceAlgorithm.hh"
 
 
class G4HadPhaseSpaceGenbod : public G4VHadPhaseSpaceAlgorithm {
public:
  G4HadPhaseSpaceGenbod(G4int verbose=0);
  virtual ~G4HadPhaseSpaceGenbod() {;}
 
protected:
  virtual void GenerateMultiBody(G4double initialMass,
                 const std::vector<G4double>& masses,
                 std::vector<G4LorentzVector>& finalState);
 
protected:
  void Initialize(G4double initialMass,
          const std::vector<G4double>& masses);
              
  void FillRandomBuffer();
 
  void ComputeWeightScale(const std::vector<G4double>& masses);
 
  void FillEnergySteps(G4double initialMass,
               const std::vector<G4double>& masses);
 
  void GenerateMomenta(const std::vector<G4double>& masses,
               std::vector<G4LorentzVector>& finalState);
 
  void AccumulateFinalState(size_t i,
                const std::vector<G4double>& masses,
                std::vector<G4LorentzVector>& finalState);
 
  G4bool AcceptEvent() const;   // Use accept-reject to generate distribution
  G4double ComputeWeight() const;
 
private:
  size_t nFinal;        // Number of final state particles
  G4double totalMass;       // Sum of final state masses
  G4double massExcess;      // Available kinetic energy
  G4double weightMax;       // Maximum possible weight
  G4int nTrials;        // Accept/reject cycles taken
 
  std::vector<G4double> msum;   // Cumulative sum of masses
  std::vector<G4double> msq;    // Final state squared masses
  std::vector<G4double> rndm;   // Random sequence for effective masses
  std::vector<G4double> meff;   // Random final-state effective masses
  std::vector<G4double> pd; // Random momentum magnitudes
};
 
#endif  /* G4HadPhaseSpaceGenbod_HH */