Gabriele Cosmo
267 lines
8.0 KiB
C++
267 lines
8.0 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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// $Id: G4PairProductionRelModel.hh 106628 2017-10-17 06:25:38Z gcosmo $
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//
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// -------------------------------------------------------------------
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//
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// GEANT4 Class header file
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//
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//
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// File name: G4PairProductionRelModel
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//
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// Author: Andreas Schaelicke
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//
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// Creation date: 02.04.2009
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//
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// Modifications:
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//
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// Class Description:
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//
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// Implementation of gamma convertion to e+e- in the field of a nucleus
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// relativistic approximation
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//
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// -------------------------------------------------------------------
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//
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#ifndef G4PairProductionRelModel_h
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#define G4PairProductionRelModel_h 1
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#include <CLHEP/Units/PhysicalConstants.h>
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#include "G4VEmModel.hh"
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#include "G4PhysicsTable.hh"
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#include "G4Log.hh"
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#include "G4Exp.hh"
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#include "G4Pow.hh"
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class G4ParticleChangeForGamma;
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class G4PairProductionRelModel : public G4VEmModel
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{
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public:
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explicit G4PairProductionRelModel(const G4ParticleDefinition* p = nullptr,
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const G4String& nam = "BetheHeitlerLPM");
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virtual ~G4PairProductionRelModel();
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virtual void Initialise(const G4ParticleDefinition*,
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const G4DataVector&) override;
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virtual void InitialiseLocal(const G4ParticleDefinition*,
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G4VEmModel* masterModel) override;
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virtual G4double ComputeCrossSectionPerAtom(
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const G4ParticleDefinition*,
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G4double kinEnergy,
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G4double Z,
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G4double A=0.,
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G4double cut=0.,
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G4double emax=DBL_MAX) override;
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virtual void SampleSecondaries(std::vector<G4DynamicParticle*>*,
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const G4MaterialCutsCouple*,
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const G4DynamicParticle*,
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G4double tmin,
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G4double maxEnergy) override;
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virtual void SetupForMaterial(const G4ParticleDefinition*,
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const G4Material*,G4double) override;
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// * fast inline functions *
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inline void SetCurrentElement(G4double Z);
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// set / get methods
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inline void SetLPMconstant(G4double val);
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inline G4double LPMconstant() const;
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inline void SetLPMflag(G4bool);
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inline G4bool LPMflag() const;
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protected:
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// screening functions
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inline G4double Phi1(G4double delta) const;
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inline G4double Phi2(G4double delta) const;
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inline G4double ScreenFunction1(G4double ScreenVariable);
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inline G4double ScreenFunction2(G4double ScreenVariable);
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inline G4double DeltaMax() const;
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inline G4double DeltaMin(G4double) const;
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// lpm functions
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void CalcLPMFunctions(G4double k, G4double eplus);
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G4double ComputeXSectionPerAtom(G4double totalEnergy, G4double Z);
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G4double ComputeDXSectionPerAtom(G4double eplusEnergy, G4double totalEnergy, G4double Z);
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G4double ComputeRelDXSectionPerAtom(G4double eplusEnergy, G4double totalEnergy, G4double Z);
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// hide assignment operator
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G4PairProductionRelModel & operator=
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(const G4PairProductionRelModel &right) = delete;
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G4PairProductionRelModel(const G4PairProductionRelModel&) = delete;
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G4Pow* g4calc;
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G4ParticleDefinition* theGamma;
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G4ParticleDefinition* theElectron;
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G4ParticleDefinition* thePositron;
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G4ParticleChangeForGamma* fParticleChange;
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G4double fLPMconstant;
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G4bool fLPMflag;
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// cash
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G4double z13, z23, lnZ;
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G4double Fel, Finel, fCoulomb;
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G4double currentZ;
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// LPM effect
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G4double lpmEnergy;
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G4double xiLPM, phiLPM, gLPM;
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// consts
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G4bool use_completescreening;
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static const G4double xgi[8], wgi[8];
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static const G4double Fel_light[5];
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static const G4double Finel_light[5];
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static const G4double facFel;
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static const G4double facFinel;
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static const G4double preS1, logTwo, xsfactor, Egsmall, Eghigh;
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};
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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inline
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void G4PairProductionRelModel::SetLPMconstant(G4double val)
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{
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fLPMconstant = val;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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inline
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G4double G4PairProductionRelModel::LPMconstant() const
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{
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return fLPMconstant;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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inline
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void G4PairProductionRelModel::SetLPMflag(G4bool val)
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{
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fLPMflag = val;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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inline
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G4bool G4PairProductionRelModel::LPMflag() const
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{
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return fLPMflag;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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inline void G4PairProductionRelModel::SetCurrentElement(G4double Z)
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{
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if(Z != currentZ) {
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currentZ = Z;
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G4int iz = G4lrint(Z);
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z13 = g4calc->Z13(iz);
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z23 = z13*z13;
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lnZ = g4calc->logZ(iz);
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if (iz <= 4) {
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Fel = Fel_light[iz];
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Finel = Finel_light[iz] ;
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}
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else {
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Fel = facFel - lnZ/3. ;
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Finel = facFinel - 2.*lnZ/3. ;
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}
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fCoulomb=GetCurrentElement()->GetfCoulomb();
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}
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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inline G4double G4PairProductionRelModel::Phi1(G4double delta) const
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{
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return (delta > 1.)
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? 21.12 - 4.184*G4Log(delta+0.952)
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: 20.868 - delta*(3.242 - 0.625*delta);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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inline G4double G4PairProductionRelModel::Phi2(G4double delta) const
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{
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return (delta > 1.)
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? 21.12 - 4.184*G4Log(delta+0.952)
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: 20.209 - delta*(1.930 + 0.086*delta);
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}
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inline G4double G4PairProductionRelModel::ScreenFunction1(G4double ScreenVariable)
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// compute the value of the screening function 3*PHI1 - PHI2
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{
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return (ScreenVariable > 1.)
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? 42.24 - 8.368*G4Log(ScreenVariable+0.952)
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: 42.392 - ScreenVariable*(7.796 - 1.961*ScreenVariable);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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inline G4double G4PairProductionRelModel::ScreenFunction2(G4double ScreenVariable)
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// compute the value of the screening function 1.5*PHI1 + 0.5*PHI2
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{
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return (ScreenVariable > 1.)
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? 42.24 - 8.368*G4Log(ScreenVariable+0.952)
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: 41.405 - ScreenVariable*(5.828 - 0.8945*ScreenVariable);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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inline G4double G4PairProductionRelModel::DeltaMax() const
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{
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// k > 50 MeV
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G4double FZ = 8.*(lnZ/3. + fCoulomb);
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return G4Exp( (42.24-FZ)/8.368 ) + 0.952;
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}
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inline G4double G4PairProductionRelModel::DeltaMin(G4double k) const
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{
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return 544.*CLHEP::electron_mass_c2/(z13*k);
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}
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#endif
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