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geant4/source/processes/hadronic/util/include/G4HadDecayGenerator.hh
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2021-06-25 16:12:29 +02:00

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//
// ********************************************************************
// * License and Disclaimer *
// * *
// * The Geant4 software is copyright of the Copyright Holders of *
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// * conditions of the Geant4 Software License, included in the file *
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// * This code implementation is the result of the scientific and *
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//
//
// Multibody "phase space" generator, which provides interface to
// algorithms for sampling. Momentum vectors are generated in the
// center-of-mass frame of the decay, and returned in a user-supplied
// buffer.
//
// Sampling algorithm is specified via constructor argument, either by
// code for centrally supplied algorithms (Kopylov, GENBOD, or NBody),
// or by pointer (which is owned by the generator).
//
// Author: Michael Kelsey (SLAC) <kelsey@slac.stanford.edu>
#ifndef G4HadDecayGenerator_HH
#define G4HadDecayGenerator_HH 1
#include "globals.hh"
#include "G4LorentzVector.hh"
#include <vector>
class G4ParticleDefinition;
class G4VHadDecayAlgorithm;
class G4HadDecayGenerator {
public:
// Flags to select algorithm by code in constructor
enum Algorithm { NONE=0, Kopylov=1, GENBOD=2, NBody=3 };
// Specify "standard" algorithm by code or by object (takes ownership)
G4HadDecayGenerator(Algorithm alg=Kopylov, G4int verbose=0);
G4HadDecayGenerator(G4VHadDecayAlgorithm* alg, G4int verbose=0);
virtual ~G4HadDecayGenerator();
// Enable (or disable if 0) diagnostic messages
void SetVerboseLevel(G4int verbose);
const G4String& GetAlgorithmName() const;
// Initial state (rest mass) and list of final masses
G4bool Generate(G4double initialMass,
const std::vector<G4double>& masses,
std::vector<G4LorentzVector>& finalState);
// Initial state particle and list of final masses
G4bool Generate(const G4ParticleDefinition* initialPD,
const std::vector<G4double>& masses,
std::vector<G4LorentzVector>& finalState);
// Initial state (frame) and list of final masses
// Final state particles will be boosted to initial-state frame
G4bool Generate(const G4LorentzVector& initialState,
const std::vector<G4double>& masses,
std::vector<G4LorentzVector>& finalState);
protected:
// Special case for one-body final state
G4bool GenerateOneBody(G4double initialMass,
const std::vector<G4double>& masses,
std::vector<G4LorentzVector>& finalState) const;
// Special function used by constructor for unrecognized algorithm code
void ReportInvalidAlgorithm(Algorithm alg) const;
void ReportMissingAlgorithm() const;
protected:
// SPECIAL FUNCTION FOR SUBCLASSES: A subclass may implement a
// collection of algorithms, to be switched on an event-by-event
// basis. This function allows the subclass to switch the "active"
// algorithm before Generate() is called.
//
// If this function is used by the subclass, then the subclass has
// ownership of _all_ instantiated algorithms, and should delete
// them in its own dtor. The subclass dtor must also call
// UseAlgorithm(0) to set the base algorithm to a null pointer, to
// prevent a double-delete error.
void UseAlgorithm(G4VHadDecayAlgorithm* alg) { theAlgorithm = alg; }
G4int verboseLevel;
G4VHadDecayAlgorithm* theAlgorithm;
};
#endif /* G4HadDecayGenerator_HH */