Gabriele Cosmo
104 lines
4.5 KiB
C++
104 lines
4.5 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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// Geant4 Class file
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//
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// File name: G4PolarizedComptonXS
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//
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// Author: Andreas Schaelicke
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//
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// Class Description:
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// determine the polarization of the final state
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// in a Compton scattering process employing the differential
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// cross section by F.W.Lipps & H.A.Tolhoek
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// ( Physica 20 (1954) 395 )
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#ifndef G4PolarizedComptonXS_h
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#define G4PolarizedComptonXS_h 1
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#include "globals.hh"
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#include "G4StokesVector.hh"
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#include "G4VPolarizedXS.hh"
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class G4PolarizedComptonXS : public G4VPolarizedXS
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{
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public:
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G4PolarizedComptonXS();
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~G4PolarizedComptonXS() override;
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// prepares the ingredients for the calculation of a polarization
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// dependent differential cross section
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// the kinematics is fixed (X - incoming photon energy in units of electron
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// mass, eps - outgoing photon energy in unit of incoming photon energy,
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// and polarization of the incoming particles fixed (p0, p1)
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// a flag specifies the extent to which polarization is taken into account
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void Initialize(G4double eps, G4double X, G4double phi,
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const G4StokesVector& p0, const G4StokesVector& p1,
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G4int flag = 0) override;
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// returns the differential cross section for a given polarisation state
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// of the final state particles to be used in the calculation of the
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// polarization transfer the calculation has to be initialised by calling
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// Initialize() prior to the first call of this function (see above)
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G4double XSection(const G4StokesVector& pol2,
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const G4StokesVector& pol3) override;
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// total cross section
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G4double TotalXSection(G4double xmin, G4double xmax, G4double y,
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const G4StokesVector& pol0,
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const G4StokesVector& pol1) override;
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// return expected mean polarisation
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G4StokesVector GetPol2() override;
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G4StokesVector GetPol3() override;
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G4PolarizedComptonXS& operator=(const G4PolarizedComptonXS& right) = delete;
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G4PolarizedComptonXS(const G4PolarizedComptonXS&) = delete;
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private:
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void DefineCoefficients(const G4StokesVector& pol0,
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const G4StokesVector& pol1);
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static constexpr G4double re2 =
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CLHEP::classic_electr_radius * CLHEP::classic_electr_radius *
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(4. * CLHEP::pi / CLHEP::hbarc) * (4. * CLHEP::pi / CLHEP::hbarc);
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// these variables store the information necessary to evaluate the
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// differential cross section for arbitrary final state
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// polarizations (used in XSection):
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// - part depending on the polarization of the final photon
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G4ThreeVector fPhi2;
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// - part depending on the polarization of the final electron
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G4ThreeVector fPhi3;
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// - polarization independent part
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G4double fPhi0;
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// - product of polarizations of initial particles
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G4double polxx, polyy, polzz, polxz, polzx, polyz, polzy, polxy, polyx;
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// G4double diffXSFactor, totalXSFactor;
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G4double fPolXS, fUnpXS;
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};
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#endif
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