include/Geant4/G4HadDecayGenerator.hh

0001 //
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0025 //
0026 //
0027 // Multibody "phase space" generator, which provides interface to
0028 // algorithms for sampling.  Momentum vectors are generated in the
0029 // center-of-mass frame of the decay, and returned in a user-supplied
0030 // buffer.
0031 //
0032 // Sampling algorithm is specified via constructor argument, either by
0033 // code for centrally supplied algorithms (Kopylov, GENBOD, or NBody),
0034 // or by pointer (which is owned by the generator).
0035 //
0036 // Author:  Michael Kelsey (SLAC) <kelsey@slac.stanford.edu>
0037
0038 #ifndef G4HadDecayGenerator_HH
0039 #define G4HadDecayGenerator_HH 1
0040
0041 #include "globals.hh"
0042 #include "G4LorentzVector.hh"
0043 #include <vector>
0044
0045 class G4ParticleDefinition;
0046 class G4VHadDecayAlgorithm;
0047
0048
0049 class G4HadDecayGenerator {
0050 public:
0051   // Flags to select algorithm by code in constructor
0052   enum Algorithm { NONE=0, Kopylov=1, GENBOD=2, NBody=3 };
0053
0054   // Specify "standard" algorithm by code or by object (takes ownership)
0055   G4HadDecayGenerator(Algorithm alg=Kopylov, G4int verbose=0);
0056   G4HadDecayGenerator(G4VHadDecayAlgorithm* alg, G4int verbose=0);
0057   virtual ~G4HadDecayGenerator();
0058
0059   // Enable (or disable if 0) diagnostic messages
0060   void SetVerboseLevel(G4int verbose);
0061   const G4String& GetAlgorithmName() const;
0062
0063   // Initial state (rest mass) and list of final masses
0064   G4bool Generate(G4double initialMass,
0065           const std::vector<G4double>& masses,
0066           std::vector<G4LorentzVector>& finalState);
0067
0068   // Initial state particle and list of final masses
0069   G4bool Generate(const G4ParticleDefinition* initialPD,
0070           const std::vector<G4double>& masses,
0071           std::vector<G4LorentzVector>& finalState);
0072
0073   // Initial state (frame) and list of final masses
0074   // Final state particles will be boosted to initial-state frame
0075   G4bool Generate(const G4LorentzVector& initialState,
0076           const std::vector<G4double>& masses,
0077           std::vector<G4LorentzVector>& finalState);
0078
0079 protected:
0080   // Special case for one-body final state
0081   G4bool GenerateOneBody(G4double initialMass,
0082              const std::vector<G4double>& masses,
0083              std::vector<G4LorentzVector>& finalState) const;
0084
0085   // Special function used by constructor for unrecognized algorithm code
0086   void ReportInvalidAlgorithm(Algorithm alg) const;
0087   void ReportMissingAlgorithm() const;
0088
0089 protected:
0090   // SPECIAL FUNCTION FOR SUBCLASSES: A subclass may implement a
0091   // collection of algorithms, to be switched on an event-by-event
0092   // basis.  This function allows the subclass to switch the "active"
0093   // algorithm before Generate() is called.
0094   //
0095   // If this function is used by the subclass, then the subclass has
0096   // ownership of _all_ instantiated algorithms, and should delete
0097   // them in its own dtor.  The subclass dtor must also call
0098   // UseAlgorithm(0) to set the base algorithm to a null pointer, to
0099   // prevent a double-delete error.
0100   void UseAlgorithm(G4VHadDecayAlgorithm* alg) { theAlgorithm = alg; }
0101
0102   G4int verboseLevel;
0103   G4VHadDecayAlgorithm* theAlgorithm;
0104 };
0105
0106 #endif  /* G4HadDecayGenerator_HH */