Gabriele Cosmo
275 lines
7.8 KiB
C++
275 lines
7.8 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: G4WentzelVIRelXSection.hh 96934 2016-05-18 09:10:41Z gcosmo $
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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: G4WentzelVIRelXSection
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//
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// Authors: V.Ivanchenko
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//
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// Creation date: 08.06.2012 from G4WentzelOKandVIxSection
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//
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// Modifications:
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//
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//
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// Class Description:
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//
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// Implementation of the computation of total and transport cross sections,
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// sample scattering angle for the single scattering case.
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// to be used by single and multiple scattering models. References:
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// 1) G.Wentzel, Z. Phys. 40 (1927) 590.
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// 2) J.M. Fernandez-Varea et al., NIM B73 (1993) 447.
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//
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// -------------------------------------------------------------------
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//
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#ifndef G4WentzelVIRelXSection_h
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#define G4WentzelVIRelXSection_h 1
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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#include "globals.hh"
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#include "G4Material.hh"
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#include "G4Element.hh"
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#include "G4ElementVector.hh"
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#include "G4NistManager.hh"
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#include "G4ThreeVector.hh"
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#include "G4Pow.hh"
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class G4ParticleDefinition;
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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class G4WentzelVIRelXSection
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{
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public:
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explicit G4WentzelVIRelXSection(G4bool combined = true);
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virtual ~G4WentzelVIRelXSection();
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void Initialise(const G4ParticleDefinition*, G4double CosThetaLim);
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void SetupParticle(const G4ParticleDefinition*);
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// return cos(ThetaMax) for msc and cos(thetaMin) for single scattering
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// cut = DBL_MAX means no scattering off electrons
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G4double SetupTarget(G4int Z, G4double cut);
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G4double ComputeTransportCrossSectionPerAtom(G4double CosThetaMax);
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G4ThreeVector& SampleSingleScattering(G4double CosThetaMin,
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G4double CosThetaMax,
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G4double elecRatio);
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inline G4double ComputeNuclearCrossSection(G4double CosThetaMin,
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G4double CosThetaMax);
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inline G4double ComputeElectronCrossSection(G4double CosThetaMin,
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G4double CosThetaMax);
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inline G4double SetupKinematic(G4double kinEnergy,
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const G4Material* mat,
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G4double cut,
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G4double tmass);
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inline G4double GetMomentumSquare() const;
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inline G4double GetCosThetaNuc() const;
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inline G4double GetCosThetaElec() const;
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private:
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void ComputeMaxElectronScattering(G4double cut);
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// hide assignment operator
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G4WentzelVIRelXSection & operator=
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(const G4WentzelVIRelXSection &right) = delete;
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G4WentzelVIRelXSection(const G4WentzelVIRelXSection&) = delete;
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const G4ParticleDefinition* theProton;
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const G4ParticleDefinition* theElectron;
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const G4ParticleDefinition* thePositron;
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const G4Material* currentMaterial;
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G4NistManager* fNistManager;
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G4Pow* fG4pow;
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G4ThreeVector temp;
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G4double numlimit;
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// integer parameters
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G4int nwarnings;
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G4int nwarnlimit;
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G4bool isCombined;
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// single scattering parameters
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G4double coeff;
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G4double cosTetMaxElec;
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G4double cosTetMaxNuc;
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G4double cosThetaMax;
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G4double alpha2;
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// projectile
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const G4ParticleDefinition* particle;
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G4double chargeSquare;
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G4double charge3;
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G4double spin;
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G4double mass;
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G4double tkin;
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G4double mom2;
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G4double momCM2;
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G4double invbeta2;
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G4double kinFactor;
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G4double etag;
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G4double ecut;
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G4double lowEnergyLimit;
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// target
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G4int targetZ;
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G4double targetMass;
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G4double screenZ;
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G4double formfactA;
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G4double factorA2;
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G4double factB;
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G4double factB1;
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G4double factD;
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G4double gam0pcmp;
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G4double pcmp2;
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static G4double ScreenRSquare[100];
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static G4double FormFactor[100];
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};
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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inline G4double
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G4WentzelVIRelXSection::SetupKinematic(G4double kinEnergy,
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const G4Material* mat,
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G4double cut,
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G4double tmass)
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{
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if(kinEnergy != tkin || mat != currentMaterial ||
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ecut != cut || tmass != targetMass) {
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currentMaterial = mat;
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ecut = cut;
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tkin = kinEnergy;
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G4double momLab2 = tkin*(tkin + 2.0*mass);
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G4double etot = tkin + mass;
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G4double ptot = std::sqrt(momLab2);
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G4double m12 = mass*mass;
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targetMass = tmass;
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// relativistic reduced mass from publucation
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// A.P. Martynenko, R.N. Faustov, Teoret. mat. Fiz. 64 (1985) 179
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//incident particle & target nucleus
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G4double Ecm = std::sqrt(m12 + targetMass*targetMass + 2.0*etot*targetMass);
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G4double mu_rel = mass*targetMass/Ecm;
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G4double momCM = ptot*targetMass/Ecm;
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// relative system
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mom2 = momCM*momCM;
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invbeta2 = 1.0 + mu_rel*mu_rel/mom2;
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factB = spin/invbeta2;
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factD = std::sqrt(mom2)/tmass;
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if(isCombined) {
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G4double cost = 1.-factorA2*mat->GetIonisation()->GetInvA23()/mom2;
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if(cost > cosTetMaxNuc) { cosTetMaxNuc = cost; }
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}
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}
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return cosTetMaxNuc;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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inline G4double G4WentzelVIRelXSection::GetMomentumSquare() const
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{
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return mom2;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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inline G4double G4WentzelVIRelXSection::GetCosThetaNuc() const
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{
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return cosTetMaxNuc;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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inline G4double G4WentzelVIRelXSection::GetCosThetaElec() const
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{
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return cosTetMaxElec;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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inline G4double
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G4WentzelVIRelXSection::ComputeNuclearCrossSection(G4double cosTMin,
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G4double cosTMax)
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{
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G4double xsec = 0.0;
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if(cosTMax < cosTMin) {
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xsec = targetZ*kinFactor*(cosTMin - cosTMax)/
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((1.0 - cosTMin + screenZ)*(1.0 - cosTMax + screenZ));
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}
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return xsec;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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inline G4double
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G4WentzelVIRelXSection::ComputeElectronCrossSection(G4double cosTMin,
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G4double cosTMax)
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{
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G4double xsec = 0.0;
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G4double cost1 = std::max(cosTMin,cosTetMaxElec);
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G4double cost2 = std::max(cosTMax,cosTetMaxElec);
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if(cost1 > cost2) {
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xsec = kinFactor*(cost1 - cost2)/
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((1.0 - cost1 + screenZ)*(1.0 - cost2 + screenZ));
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}
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return xsec;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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#endif
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