Gabriele Cosmo
264 lines
7.5 KiB
C++
264 lines
7.5 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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//
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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: G4UrbanMscModel
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//
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// Author: Laszlo Urban
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//
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// Creation date: 19.02.2013
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//
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// Created from G4UrbanMscModel96
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//
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// New parametrization for theta0
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// Correction for very small step length
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//
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// Class Description:
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//
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// Implementation of the model of multiple scattering based on
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// H.W.Lewis Phys Rev 78 (1950) 526 and L.Urban model
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// -------------------------------------------------------------------
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//
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#ifndef G4UrbanMscModel_h
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#define G4UrbanMscModel_h 1
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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#include <CLHEP/Units/SystemOfUnits.h>
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#include "G4VMscModel.hh"
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#include "G4MscStepLimitType.hh"
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#include "G4Log.hh"
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#include "G4Exp.hh"
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class G4ParticleChangeForMSC;
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class G4SafetyHelper;
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class G4LossTableManager;
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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class G4UrbanMscModel : public G4VMscModel
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{
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public:
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explicit G4UrbanMscModel(const G4String& nam = "UrbanMsc");
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virtual ~G4UrbanMscModel();
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virtual void Initialise(const G4ParticleDefinition*,
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const G4DataVector&) override;
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virtual void StartTracking(G4Track*) override;
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virtual G4double
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ComputeCrossSectionPerAtom(const G4ParticleDefinition* particle,
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G4double KineticEnergy,
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G4double AtomicNumber,
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G4double AtomicWeight=0.,
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G4double cut =0.,
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G4double emax=DBL_MAX) override;
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virtual G4ThreeVector& SampleScattering(const G4ThreeVector&,
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G4double safety) override;
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virtual G4double
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ComputeTruePathLengthLimit(const G4Track& track,
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G4double& currentMinimalStep) override;
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virtual G4double ComputeGeomPathLength(G4double truePathLength) override;
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virtual G4double ComputeTrueStepLength(G4double geomStepLength) override;
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G4double ComputeTheta0(G4double truePathLength, G4double KineticEnergy);
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private:
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G4double SampleCosineTheta(G4double trueStepLength, G4double KineticEnergy);
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void SampleDisplacement(G4double sinTheta, G4double phi);
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void SampleDisplacementNew(G4double sinTheta, G4double phi);
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inline void SetParticle(const G4ParticleDefinition*);
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inline void UpdateCache();
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inline G4double Randomizetlimit();
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inline G4double SimpleScattering(G4double xmeanth, G4double x2meanth);
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// hide assignment operator
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G4UrbanMscModel & operator=(const G4UrbanMscModel &right) = delete;
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G4UrbanMscModel(const G4UrbanMscModel&) = delete;
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CLHEP::HepRandomEngine* rndmEngineMod;
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const G4ParticleDefinition* particle;
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const G4ParticleDefinition* positron;
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G4ParticleChangeForMSC* fParticleChange;
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const G4MaterialCutsCouple* couple;
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G4LossTableManager* theManager;
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G4double mass;
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G4double charge,ChargeSquare;
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G4double masslimite,lambdalimit,fr;
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G4double taubig;
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G4double tausmall;
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G4double taulim;
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G4double currentTau;
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G4double tlimit;
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G4double tlimitmin;
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G4double tlimitminfix,tlimitminfix2;
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G4double tgeom;
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G4double geombig;
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G4double geommin;
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G4double geomlimit;
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G4double skindepth;
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G4double smallstep;
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G4double presafety;
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G4double lambda0;
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G4double lambdaeff;
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G4double tPathLength;
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G4double zPathLength;
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G4double par1,par2,par3;
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G4double stepmin;
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G4double stepmina,stepminb;
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G4double currentKinEnergy;
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G4double currentLogKinEnergy;
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G4double currentRange;
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G4double rangeinit;
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G4double currentRadLength;
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G4int currentMaterialIndex;
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G4double Zold;
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G4double Zeff,Z2,Z23,lnZ;
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G4double coeffth1,coeffth2;
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G4double coeffc1,coeffc2,coeffc3,coeffc4;
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G4bool firstStep;
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G4bool insideskin;
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G4bool latDisplasmentbackup ;
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G4bool dispAlg96;
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G4double rangecut;
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G4double drr,finalr;
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};
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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inline
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void G4UrbanMscModel::SetParticle(const G4ParticleDefinition* p)
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{
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if (p != particle) {
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particle = p;
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mass = p->GetPDGMass();
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charge = p->GetPDGCharge()/CLHEP::eplus;
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ChargeSquare = charge*charge;
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}
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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inline G4double G4UrbanMscModel::Randomizetlimit()
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{
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G4double res = tlimitmin;
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if(tlimit > tlimitmin)
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{
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res = G4RandGauss::shoot(rndmEngineMod,tlimit,0.1*(tlimit-tlimitmin));
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res = std::max(res, tlimitmin);
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}
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return res;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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inline void G4UrbanMscModel::UpdateCache()
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{
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lnZ = G4Log(Zeff);
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// correction in theta0 formula
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G4double w = G4Exp(lnZ/6.);
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G4double facz = 0.990395+w*(-0.168386+w*0.093286) ;
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coeffth1 = facz*(1. - 8.7780e-2/Zeff);
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coeffth2 = facz*(4.0780e-2 + 1.7315e-4*Zeff);
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// tail parameters
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G4double Z13 = w*w;
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coeffc1 = 2.3785 - Z13*(4.1981e-1 - Z13*6.3100e-2);
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coeffc2 = 4.7526e-1 + Z13*(1.7694 - Z13*3.3885e-1);
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coeffc3 = 2.3683e-1 - Z13*(1.8111 - Z13*3.2774e-1);
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coeffc4 = 1.7888e-2 + Z13*(1.9659e-2 - Z13*2.6664e-3);
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Z2 = Zeff*Zeff;
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Z23 = Z13*Z13;
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stepmina = 15.99/(1.+0.119*Zeff);
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stepminb = 4.39/(1.+0.079*Zeff);
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Zold = Zeff;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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inline
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G4double G4UrbanMscModel::SimpleScattering(G4double xmeanth, G4double x2meanth)
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{
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// 'large angle scattering'
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// 2 model functions with correct xmean and x2mean
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G4double a = (2.*xmeanth+9.*x2meanth-3.)/(2.*xmeanth-3.*x2meanth+1.);
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G4double prob = (a+2.)*xmeanth/a;
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// sampling
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G4double rdm = rndmEngineMod->flat();
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G4double cth = (rndmEngineMod->flat() < prob)
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? -1.+2.*G4Exp(G4Log(rdm)/(a+1.)) : -1.+2.*rdm;
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return cth;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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#endif
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