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// $Id$
//
// -----------------------------------------------------------------------------
//      GEANT 4 class header file
//
//                 History: 
//     Created by Mikhail Kossov, October 2006
//     CHIPS QGS fragmentation class
//     For comparison mirror member functions are taken from G4 classes:
//     G4QGSParticipants
//     G4QGSModels
//     G4ExcitedStringDecay
// -----------------------------------------------------------------------------
// Short description: CHIPS string fragmentation class for ion-ion inelastic
// -----------------------------------------------------------------------------
//
#ifndef G4QIonIonCollision_h
#define G4QIonIonCollision_h 1

#include "globals.hh"
#include "G4LorentzVector.hh"
#include "Randomize.hh"
#include "G4QNucleus.hh"
#include "G4Quasmon.hh"
#include "G4QHadronVector.hh"
#include "G4QEnvironment.hh"
#include "G4QInteractionVector.hh"
#include "G4QProbability.hh"
#include "G4QPartonPairVector.hh" 
#include "G4QuasiFreeRatios.hh"
#include "G4QStringVector.hh" 

class G4QIonIonCollision
{
 public:
  G4QIonIonCollision(G4QNucleus& pNucleus, const G4QNucleus& tNucleus);
  ~G4QIonIonCollision(); 

  G4QHadronVector* Fragment(); // Calls Breeder & fragments Quasmons inside ResidualNucleus

  // Static functions
  static void SetParameters(G4int nC, G4double strTens, G4double tubeDens, G4double SigPt);

 protected:
  G4bool ExciteDiffParticipants(G4QHadron* aPartner, G4QHadron* bPartner) const; //@@Once
  G4bool ExciteSingDiffParticipants(G4QHadron* aPartner, G4QHadron* bPartner) const;//@@Onc
  std::pair<G4int,G4int> ReducePair(G4int P1, G4int P2) const; // Reduce Q-pairs to singles
  void Breeder(); // String fragmentation algoritm, which makes Hadrons & Quasmons from Str
  // @@ At present always SingleDiffractive, so this is a fake member function
  G4bool IsSingleDiffractive() {G4bool r=false; if(G4UniformRand()<1.) r=true; return r;}
  G4int SumPartonPDG(G4int PDG1, G4int PFG2) const;
  G4double ChooseX(G4double Xmin, G4double Xmax) const;
  G4ThreeVector GaussianPt(G4double widthSquare, G4double maxPtSquare) const;
  G4int AnnihilationOrder(G4int LS, G4int MS, G4int uP, G4int mP, G4int sP, G4int nP);
  void SwapPartons(); // Try to swap partons of strings, if one of strings has negative M2

 private:
  enum {SOFT, DIFFRACTIVE};
  // static model parameters
  static G4int    nCutMax;                               // Maximum number of Soft Cuts 
  static G4double stringTension;                         // String Tension to absorb energy
  static G4double tubeDensity;                           // Nucleon density in the FluxTube
  static G4double widthOfPtSquare;                       // width^2 of pt(StringExcitation)

  // Body
  G4QNucleus      theProjNucleus;                        // ProjectileNucleus moving LS->CM
  G4QNucleus      theTargNucleus;                        // TargetNucleus moving fromLStoCM
  G4QStringVector strings;                               // Vector of created strings
  G4QuasmonVector theQuasmons;                           // Strings converter to Quasmons
  G4QHadronVector* theResult;                            // Pointer to the OUTPUT Result
  G4double        maxEn;                                 // Energy absorbed by the nucleus
  G4double        maxNuc;                                // #0fNucleons in the Flux Tube
  G4QCHIPSWorld*  theWorld;                              // Pointer to the CHIPS World
};

#endif