00001 // 00002 // ******************************************************************** 00003 // * License and Disclaimer * 00004 // * * 00005 // * The Geant4 software is copyright of the Copyright Holders of * 00006 // * the Geant4 Collaboration. It is provided under the terms and * 00007 // * conditions of the Geant4 Software License, included in the file * 00008 // * LICENSE and available at http://cern.ch/geant4/license . These * 00009 // * include a list of copyright holders. * 00010 // * * 00011 // * Neither the authors of this software system, nor their employing * 00012 // * institutes,nor the agencies providing financial support for this * 00013 // * work make any representation or warranty, express or implied, * 00014 // * regarding this software system or assume any liability for its * 00015 // * use. Please see the license in the file LICENSE and URL above * 00016 // * for the full disclaimer and the limitation of liability. * 00017 // * * 00018 // * This code implementation is the result of the scientific and * 00019 // * technical work of the GEANT4 collaboration. * 00020 // * By using, copying, modifying or distributing the software (or * 00021 // * any work based on the software) you agree to acknowledge its * 00022 // * use in resulting scientific publications, and indicate your * 00023 // * acceptance of all terms of the Geant4 Software license. * 00024 // ******************************************************************** 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