G4CascadeFinalStateAlgorithm.hh

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//
// Author:  Michael Kelsey (SLAC)
// Date:    15 April 2013
//
// Description: Subclass of models/util G4VHadDecayAlgorithm which uses
//      old INUCL parametrizations for momentum and angular
//      distributions.
//
 
#ifndef G4CascadeFinalStateAlgorithm_hh
#define G4CascadeFinalStateAlgorithm_hh 1
 
#include "globals.hh"
#include "G4VHadDecayAlgorithm.hh"
#include "G4LorentzConvertor.hh"
 
class G4InuclElementaryParticle;
class G4MultiBodyMomentumDist;
class G4TwoBodyAngularDist;
class G4VMultiBodyMomDst;
class G4VTwoBodyAngDst;
 
 
class G4CascadeFinalStateAlgorithm : public G4VHadDecayAlgorithm {
public:
  G4CascadeFinalStateAlgorithm();
  virtual ~G4CascadeFinalStateAlgorithm();
 
  virtual void SetVerboseLevel(G4int verbose);  // Pass through to factories
 
  // Select appropriate distributions based on interaction
  void Configure(G4InuclElementaryParticle* bullet,
         G4InuclElementaryParticle* target,
         const std::vector<G4int>& particle_kinds);
 
protected:
  // Two-body generation uses angular-distribution function
  virtual void GenerateTwoBody(G4double initialMass,
                   const std::vector<G4double>& masses,
                   std::vector<G4LorentzVector>& finalState);
 
  // N-body generation uses momentum-modulus distribution, computed angles
  virtual void GenerateMultiBody(G4double initialMass,
                 const std::vector<G4double>& masses,
                 std::vector<G4LorentzVector>& finalState);
 
  // Compute kinematic quantities needed for distributions
  void SaveKinematics(G4InuclElementaryParticle* bullet,
              G4InuclElementaryParticle* target);
 
  // Select generator based on initial and final state
  void ChooseGenerators(G4int is, G4int fs);
 
  // Generate momentum magnitudes and validate for use
  void FillMagnitudes(G4double initialMass,
              const std::vector<G4double>& masses);
 
  G4bool satisfyTriangle(const std::vector<G4double>& pmod) const;
 
  // Generate momentum directions into final state
  void FillDirections(G4double initialMass,
              const std::vector<G4double>& masses,
              std::vector<G4LorentzVector>& finalState);
 
  void FillDirThreeBody(G4double initialMass,
            const std::vector<G4double>& masses,
            std::vector<G4LorentzVector>& finalState);
 
  void FillDirManyBody(G4double initialMass,
               const std::vector<G4double>& masses,
               std::vector<G4LorentzVector>& finalState);
 
  G4double GenerateCosTheta(G4int ptype, G4double pmod) const;
 
  // SPECIAL:  Generate N-body phase space using Kopylov algorithm
  void FillUsingKopylov(G4double initialMass,
            const std::vector<G4double>& masses,
            std::vector<G4LorentzVector>& finalState);
 
  G4double BetaKopylov(G4int K) const;  // Copied from G4HadPhaseSpaceKopylov
 
private:
  const G4VMultiBodyMomDst* momDist;    // Buffers for selected distributions
  const G4VTwoBodyAngDst* angDist;  // Will be NULL for 3+body channels
 
  std::vector<G4int> kinds;     // Copy of particle_kinds list
  G4int multiplicity;           // Final state size, for convenience
  G4double bullet_ekin;         // Kinematics needed for distributions
  G4LorentzConvertor toSCM;     // Handles complex rotations/transforms
 
  std::vector<G4double> modules;    // Buffers for generating momenta
  G4ThreeVector mom;
 
  static const G4double maxCosTheta;    // Cut for valid polar angle generation
  static const G4double oneOverE;   // Numeric value of 1/e for calculations
  static const G4double small;      // Cut for momentum/kinematics
  static const G4int itry_max;      // Maximum number of generation attempts
};
 
#endif  /* G4CascadeFinalStateAlgorithm_hh */