G4QCaptureAtRest.hh

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00025 //
00026 // $Id$
00027 //
00028 //      ---------------- G4QCaptureAtRest header ----------------
00029 //                 by Mikhail Kossov, December 2003.
00030 // Header of G4QCaptureAtRest class of the CHIPS Simulation Branch in GEANT4
00031 // -------------------------------------------------------------------------------
00032 // At present (May 2009) only pi-, K- and antiNucleon capture are tested, which
00033 // are the most crucial for the in matter simulation. The hyperon capture (Sigma-,
00034 // Xi-, Omega-, antiSigma+) is implemented, but not tested and it is not clear how
00035 // frequently this kind of interaction takes place in the simulation of the hadronic
00036 // showers. The antiNeutron Capture At Rest is implemented by this G4QCaptureAtRest
00037 // class, but it is not clear how the anti-neutrons are stopped in Geant4 tracking.
00038 // It can be stopped only by interactions with electrons, as the annihilation cross
00039 // section is huge and any interaction with nucleus results in annihilation. The
00040 // mu- & tau- Capture At Rest (mu-,nu) & (mu-,nu) are weak processes, which must
00041 // be simulated together with the reversed Betha decay (e-,nu). While mu- capture is
00042 // similar to the pi- capture from the nuclear fragmentation point of view (the energy
00043 // scale is shrinked because m_mu < m_pi and a part of the energy is lost because of
00044 // the neutrino radiation), the time scale of the mu- capture process is not exact,
00045 // but it is clear, that it is well delayed. By this reason the mu- capture can be
00046 // excluded from the G4QCaptureAtRest and can be implemented in the "LongLivingDecay"
00047 // branch of simulation, which includes excited states of nuclei and short living
00048 // isotopes. On the "Fast Simulation" Level all radioactive isotopes, long living
00049 // nuclear excitations, mu-atoms etc, which can be important for the background
00050 // signals, must be collected in the continuous database and simulated separately.
00051 // CHIPS is SU(3) event generator, so it does not include reactions with the heavy
00052 // (c,b,t) quarks involved such as antiDs-, which can be simulated only by SU(6)
00053 // QUIPS (QUark Invariant Phase Space) model. - May 2009, M.Kossov.-
00054 // -------------------------------------------------------------------------------
00055 // All algorithms are similar: the captured particle is absorbed by a nuclear cluster
00056 // with the subsequent Quark Exchange nuclear fragmentation. The Anti-Proton (antiSigma+)
00057 // Capture algorithm is more complicated: the anti-baryon annihilates with the quasyfree
00058 // nucleons on the nuclear periphery. The peripheral interaction results in a number
00059 // of mesons. A part of them misses the nucleus and comes directly to the output,
00060 // while others create Multy Quasmon Excitation in the nucleus with the subsequent
00061 // Quark Excange Fragmentation of the nucleus. At present the two step mechanism of
00062 // the antiProton-Nucleus interaction is hardwired in the G4QEnvironment class, but
00063 // with time the first step of the interaction can be moved to this G4QCaptureAtRest
00064 // class, to make the G4QEnvirement class simpler and better defined. This is
00065 // necessary because the G4QEnvironment class is going to loos the previlage of
00066 // the CHIPS Head Class (as previously the G4Quasmon class lost it) and G4QCollision
00067 // class is going to be the CHIPS Head Class, where a few Nuclear Environments can
00068 // exist (e.g. the Nuclear Environment of the Projectile Nucleus and the Nuclear
00069 // Environment of the Target Nucleus). By the way, the antiProton-H1 interaction At
00070 // Rest (CHIPSI) can be still simulated with only the G4Quasmon class, as this
00071 // reaction does not have any nuclear environment.- May 2009, Mikhail Kossov.-
00072 // --------------------------------------------------------------------------------
00073 // ****************************************************************************************
00074 // This Header is a part of the CHIPS physics package (author: M. Kosov)
00075 // ****************************************************************************************
00076 // Short Description: This is a universal process for nuclear capture
00077 // (including annihilation) of all negative particles (cold neutrons, negative
00078 // hadrons, negative leptons: mu- & tau-). It can be used for the cold neutron
00079 // capture, but somebody should decide what is the probability (defined
00080 // by the capture cross-section and atomic material properties) to switch
00081 // the cold neutron to the at-rest neutron. - M.K. 2009.
00082 // ----------------------------------------------------------------------
00083 
00084 #ifndef G4QCaptureAtRest_hh
00085 #define G4QCaptureAtRest_hh
00086 
00087 // GEANT4 Headers
00088 #include "globals.hh"
00089 #include "G4ios.hh"
00090 #include "G4VRestProcess.hh"
00091 #include "G4ParticleTypes.hh"
00092 #include "G4VParticleChange.hh"
00093 #include "G4ParticleDefinition.hh"
00094 #include "G4DynamicParticle.hh"
00095 #include "Randomize.hh"
00096 #include "G4ThreeVector.hh"
00097 #include "G4LorentzVector.hh"
00098 #include "G4RandomDirection.hh"
00099 
00100 // CHIPS Headers
00101 #include "G4QEnvironment.hh"
00102 #include "G4QIsotope.hh"
00103 #include "G4QPDGToG4Particle.hh"
00104 
00105 class G4QCaptureAtRest : public G4VRestProcess
00106 {  
00107 private:
00108 
00109   // Hide assignment operator as private 
00110   G4QCaptureAtRest& operator=(const G4QCaptureAtRest &right);
00111 
00112   // Copy constructor
00113   G4QCaptureAtRest(const G4QCaptureAtRest& );
00114 
00115 public:
00116 
00117   // Constructor
00118   G4QCaptureAtRest(const G4String& processName ="CHIPSNuclearCaptureAtRest");
00119 
00120   // Destructor
00121   virtual ~G4QCaptureAtRest();
00122 
00123   virtual G4bool IsApplicable(const G4ParticleDefinition& particle);
00124 
00125   G4VParticleChange* AtRestDoIt(const G4Track& aTrack, const G4Step& aStep); 
00126 
00127   G4LorentzVector GetEnegryMomentumConservation();
00128 
00129   G4int GetNumberOfNeutronsInTarget();
00130 
00131   // Static functions
00132   static void SetManual();
00133   static void SetStandard();
00134   static void SetParameters(G4double temper=180., G4double ssin2g=.1, G4double etaetap=.3,
00135                             G4double fN=0., G4double fD=0., G4double cP=1., G4double mR=1.,
00136                             G4int npCHIPSWorld=234, G4double solAn=.5, G4bool efFlag=false,
00137                             G4double piTh=141.4,G4double mpi2=20000.,G4double dinum=1880.);
00138 
00139 protected:                         
00140 
00141   // zero mean lifetime
00142   G4double GetMeanLifeTime(const G4Track& aTrack, G4ForceCondition* );
00143   G4double RandomizeDecayElectron(G4int Z); // Randomize energy of decay electron (in MeV)
00144 private:
00145 
00146   G4bool RandomizeMuDecayOrCapture(G4int Z, G4int N); // true=MuCapture, false=MuDecay
00147   void CalculateEnergyDepositionOfMuCapture(G4int Z); // (2p->1s, MeV) @@ Now N-independent
00148   G4bool RandomizeTauDecayOrCapture(G4int Z, G4int N);// true=TauCapture, false=TauDecay
00149   void CalculateEnergyDepositionOfTauCapture(G4int Z);// (2p->1s, MeV) @@N-independ,Improve
00150 
00151 // BODY
00152 private:
00153   // Static Parameters
00154   static G4bool   manualFlag;  // If false then standard parameters are used
00155   static G4int    nPartCWorld; // The#of particles for hadronization (limit of A of fragm.)
00156   // -> Parameters of the G4Quasmon class:
00157   static G4double Temperature; // Quasmon Temperature
00158   static G4double SSin2Gluons; // Percent of ssbar sea in a constituen gluon
00159   static G4double EtaEtaprime; // Part of eta-prime in all etas
00160   // -> Parameters of the G4QNucleus class:
00161   static G4double freeNuc;     // probability of the quasi-free baryon on surface
00162   static G4double freeDib;     // probability of the quasi-free dibaryon on surface
00163   static G4double clustProb;   // clusterization probability in dense region
00164   static G4double mediRatio;   // relative vacuum hadronization probability
00165   // -> Parameters of the G4QEnvironment class:
00166   static G4bool   EnergyFlux;  // Flag for Energy Flux use instead of Multy Quasmon
00167   static G4double SolidAngle;  // Part of Solid Angle to capture secondaries(@@A-dep)
00168   static G4double PiPrThresh;  // Pion Production Threshold for gammas
00169   static G4double M2ShiftVir;  // Shift for M2=-Q2=m_pi^2 of the virtual gamma
00170   static G4double DiNuclMass;  // Double Nucleon Mass for virtual normalization
00171   //
00172   // Working parameters
00173   G4LorentzVector EnMomConservation;                  // Residual of Energy/Momentum Cons.
00174   G4int nOfNeutrons;                                  // #of neutrons in the target nucleus
00175   // Modifires for the reaction
00176   G4double Time;                                      // Time shift of the capture reaction
00177   G4double EnergyDeposition;                          // Energy deposited in the reaction
00178 
00179 };
00180 #endif

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