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//
// $Id$
//
// 20100114  M. Kelsey -- Remove G4CascadeMomentum, use G4LorentzVector directly
// 20100315  M. Kelsey -- Remove "using" directive and unnecessary #includes.
// 20100407  M. Kelsey -- Eliminate return-by-value std::vector<> by creating
//		three data buffers for particles, momenta, and particle types.
//		The following functions now return void and are non-const:
//		  ::generateSCMfinalState()
//		  ::generateMomModules() (also remove input vector)
//		  ::generateStrangeChannelPartTypes()
//		  ::generateSCMpionAbsorption()
// 20100413  M. Kelsey -- Pass G4CollisionOutput by ref to ::collide(); merge
//		public vs. private ::collide() functions.
// 20100511  M. Kelsey -- Remove G4PionSampler and G4NucleonSampler.  Expand
//		particle-types selector to all modes, not just strangeness.
// 20100517  M. Kelsey -- Inherit from common base class, make arrays static
// 20100714  M. Kelsey -- Switch to new G4CascadeColliderBase class
// 20100726  M. Kelsey -- Move remaining std::vector<> buffers here
// 20100804  M. Kelsey -- Add printFinalStateTables() function.
// 20110923  M. Kelsey -- Add optional stream& to printFinalStateTables().

#ifndef G4ELEMENTARY_PARTICLE_COLLIDER_HH
#define G4ELEMENTARY_PARTICLE_COLLIDER_HH

#include "G4CascadeColliderBase.hh"
#include "G4InuclElementaryParticle.hh"
#include "G4LorentzVector.hh"
#include <iosfwd>
#include <vector>

class G4LorentzConvertor;
class G4CollisionOutput;


class G4ElementaryParticleCollider : public G4CascadeColliderBase {
public:
  G4ElementaryParticleCollider();
  virtual ~G4ElementaryParticleCollider() {};
  
  void collide(G4InuclParticle* bullet, G4InuclParticle* target,
	       G4CollisionOutput& output);

private:
  void initializeArrays();

  G4int generateMultiplicity(G4int is, G4double ekin) const;

  void generateOutgoingPartTypes(G4int is, G4int mult, G4double ekin);

  void generateSCMfinalState(G4double ekin, G4double etot_scm, G4double pscm,
			     G4InuclElementaryParticle* particle1,
			     G4InuclElementaryParticle* particle2, 
			     G4LorentzConvertor* toSCM); 

  void generateSCMpionAbsorption(G4double etot_scm,
				 G4InuclElementaryParticle* particle1,
				 G4InuclElementaryParticle* particle2); 

  void generateMomModules(G4int mult, G4int is, G4double ekin,
			  G4double etot_cm); 

  // Samples the CM momentum for elastic and charge exchange scattering
  //
  G4LorentzVector
  sampleCMmomentumFor2to2(G4int is, G4int kw, G4double ekin,
			  G4double pscm) const; 


  // Samples cos(theta) in the CM for elastic and charge exchange scattering
  //
  G4double sampleCMcosFor2to2(G4double pscm, G4double pFrac,
                              G4double pA, G4double pC, G4double pCos) const;


  G4double getMomModuleFor2toMany(G4int is, G4int mult, G4int knd, 
				  G4double ekin) const; 


  G4bool satisfyTriangle(const std::vector<G4double>& modules) const; 
	
  G4LorentzVector
  particleSCMmomentumFor2to3(G4int is, G4int knd, G4double ekin, 
			     G4double pmod) const; 

  void printFinalStateTables(std::ostream& os=G4cout) const;

  // Internal buffers for lists of secondaries
  std::vector<G4InuclElementaryParticle> particles;
  std::vector<G4LorentzVector> scm_momentums;
  std::vector<G4double> modules;
  std::vector<G4double> masses2;
  std::vector<G4int> particle_kinds;

  // Parameter arrays
  static const G4double rmn[14][10][2];    
  static const G4double abn[4][4][4];
};

#endif	/* G4ELEMENTARY_PARTICLE_COLLIDER_HH */