| 1 | //
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| 2 | // ********************************************************************
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| 3 | // * License and Disclaimer *
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| 4 | // * *
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of *
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and *
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| 7 | // * conditions of the Geant4 Software License, included in the file *
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| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These *
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| 9 | // * include a list of copyright holders. *
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| 10 | // * *
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| 11 | // * Neither the authors of this software system, nor their employing *
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| 12 | // * institutes,nor the agencies providing financial support for this *
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| 13 | // * work make any representation or warranty, express or implied, *
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| 14 | // * regarding this software system or assume any liability for its *
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| 15 | // * use. Please see the license in the file LICENSE and URL above *
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| 16 | // * for the full disclaimer and the limitation of liability. *
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| 17 | // * *
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| 18 | // * This code implementation is the result of the scientific and *
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| 19 | // * technical work of the GEANT4 collaboration. *
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| 20 | // * By using, copying, modifying or distributing the software (or *
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| 21 | // * any work based on the software) you agree to acknowledge its *
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| 22 | // * use in resulting scientific publications, and indicate your *
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| 23 | // * acceptance of all terms of the Geant4 Software license. *
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| 24 | // ********************************************************************
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| 25 | //
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| 26 | // $Id: G4PolarizedComptonCrossSection.hh,v 1.3 2007/11/01 17:32:34 schaelic Exp $
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| 27 | // GEANT4 tag $Name: geant4-09-03-cand-01 $
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| 28 | //
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| 29 | // GEANT4 Class file
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| 30 | //
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| 31 | //
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| 32 | // File name: G4PolarizedComptonCrossSection
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| 33 | //
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| 34 | // Author: Andreas Schaelicke
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| 35 | //
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| 36 | // Creation date: 15.05.2005
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| 37 | //
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| 38 | // Modifications:
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| 39 | // 18-07-06 use newly calculated cross sections (P. Starovoitov)
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| 40 | // 21-08-06 update interface to geant4.8.1 (A. Schaelicke)
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| 41 | // 15-10-07 introduced a more general framework for cross sections (AS)
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| 42 | //
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| 43 | //
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| 44 | // Class Description:
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| 45 | // determine the polarization of the final state
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| 46 | // in a Compton scattering process employing the differential
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| 47 | // cross section by F.W.Lipps & H.A.Tolhoek
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| 48 | // ( Physica 20 (1954) 395 )
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| 49 | //
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| 50 | #ifndef G4PolarizedComptonCrossSection_h
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| 51 | #define G4PolarizedComptonCrossSection_h 1
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| 52 |
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| 53 | #include "G4StokesVector.hh"
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| 54 | #include "G4VPolarizedCrossSection.hh"
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| 55 |
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| 56 |
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| 57 |
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| 58 | class G4PolarizedComptonCrossSection : public G4VPolarizedCrossSection
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| 59 | {
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| 60 | public:
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| 61 | G4PolarizedComptonCrossSection();
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| 62 | virtual ~G4PolarizedComptonCrossSection();
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| 63 | public:
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| 64 | // prepares the ingredients for the calculation of a polarization
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| 65 | // dependent differential cross section
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| 66 | // the kinematics is fixed (X - incoming photon energy in units of electron mass, eps - outgoing photon energy in unit of incoming photon energy,
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| 67 | // and polarization of the incoming particles fixed (p0, p1)
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| 68 | // a flag specifies the extent to which polarization is taken
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| 69 | // into account
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| 70 | virtual void Initialize(G4double eps, G4double X, G4double phi,
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| 71 | const G4StokesVector & p0,
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| 72 | const G4StokesVector & p1,
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| 73 | G4int flag=0);
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| 74 |
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| 75 | // returns the differential cross section for a given polarisation state
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| 76 | // of the final state particles to be used in the calculation of the
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| 77 | // polarization transfer
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| 78 | // the calculation has to be initialised by calling Initialize()
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| 79 | // prior to the first call of this function (see above)
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| 80 | G4double XSection(const G4StokesVector & pol2,const G4StokesVector & pol3);
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| 81 | // total cross section
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| 82 | G4double TotalXSection(G4double xmin, G4double xmax, G4double y,
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| 83 | const G4StokesVector & pol0,const G4StokesVector & pol1);
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| 84 |
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| 85 | public:
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| 86 | // return expected mean polarisation
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| 87 | G4StokesVector GetPol2();
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| 88 | G4StokesVector GetPol3();
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| 89 | private:
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| 90 | void DefineCoefficients(const G4StokesVector & pol0,
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| 91 | const G4StokesVector & pol1);
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| 92 | // states if an incoming or outgoing particle is polarized
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| 93 | G4bool gammaPol0, electronPol1, gammaPol2, electronPol3;
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| 94 |
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| 95 |
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| 96 | // these variables store the information necessary to evaluate the
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| 97 | // differential cross section for arbitrary final state
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| 98 | // polarizations (used in XSection):
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| 99 | // - polarization independent part
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| 100 | G4double phi0;
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| 101 | // - part depending on the polarization of the final photon
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| 102 | G4ThreeVector phi2;
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| 103 | // - part depending on the polarization of the final electron
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| 104 | G4ThreeVector phi3;
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| 105 | // - product of polarizations of initial particles
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| 106 | G4double polxx, polyy, polzz, polxz, polzx, polyz, polzy, polxy, polyx;
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| 107 |
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| 108 | G4double diffXSFactor, totalXSFactor, re2;
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| 109 | G4double epsilon, polXS, unpXS;
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| 110 | };
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| 111 |
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| 112 |
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| 113 | #endif
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