include/Geant4/G4PolarizationTransition.hh

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0025 //
0026 // -------------------------------------------------------------------
0027 //      GEANT4 Class file
0028 //
0029 //      File name:     G4PolarizationTransition
0030 //
0031 //      Author:        Jason Detwiler (jasondet@gmail.com)
0032 //
0033 //      Creation date: Aug 2012
0034 //
0035 //      Description:
0036 //      Stores and manipulates the statistical tensor describing the nuclear
0037 //      polarization (see Alder and Winther, "Electromagnetic Excitation" (1975),
0038 //      Appendix F). Functions are implemented for generating angular correlations
0039 //      in gamma decays, following Alder and Winther, Appendix G.
0040 //      This code assumes no polarization will be detected and uses eqs (17-20).
0041 //      Adding polarization would require using instead (13) and the more generic
0042 //      form of the statstical tensor after decay described by equation (6)
0043 //      Could be expanded to also generate e.g. gamma-beta and other
0044 //      correlations as well.
0045 //
0046 // -------------------------------------------------------------------
0047
0048 #ifndef G4POLARIZATIONTRANSITION_HH
0049 #define G4POLARIZATIONTRANSITION_HH
0050
0051 #include "globals.hh"
0052 #include "G4LegendrePolynomial.hh"
0053 #include "G4PolynomialPDF.hh"
0054 #include "G4Pow.hh"
0055
0056 class G4NuclearPolarization;
0057
0058 class G4PolarizationTransition
0059 {
0060   typedef std::vector< std::vector<G4complex> > POLAR;
0061
0062   public:
0063     explicit G4PolarizationTransition();
0064     ~G4PolarizationTransition();
0065
0066     void SampleGammaTransition(G4NuclearPolarization* np,
0067                    G4int twoJ1, G4int twoJ2,
0068                                G4int L0, G4int Lp, G4double mpRatio,
0069                    G4double& cosTheta, G4double& phi);
0070
0071     // generic static functions
0072     G4double FCoefficient(G4int K, G4int L, G4int Lprime,
0073               G4int twoJ2, G4int twoJ1) const;
0074     G4double F3Coefficient(G4int K, G4int K2, G4int K1, G4int L,
0075                G4int Lprime, G4int twoJ2, G4int twoJ1) const;
0076
0077     // transition-specific functions
0078     G4double GammaTransFCoefficient(G4int K) const;
0079     G4double GammaTransF3Coefficient(G4int K, G4int K2, G4int K1) const;
0080
0081     void DumpTransitionData(const POLAR& pol) const;
0082
0083     inline void SetVerbose(G4int val) { fVerbose = val; };
0084
0085   private:
0086
0087     G4PolarizationTransition(const G4PolarizationTransition &right) = delete;
0088     const G4PolarizationTransition& operator=(const G4PolarizationTransition &right) = delete;
0089
0090     // Gamma angle generation and decay: call these functions in this order!
0091     // All angles are in the same coordinate system: user may choose any axis
0092     G4double GenerateGammaCosTheta(const POLAR&);
0093     G4double GenerateGammaPhi(G4double& cosTheta, const POLAR&);
0094
0095     inline G4double LnFactorial(int k) const { return G4Pow::GetInstance()->logfactorial(k); }
0096
0097     G4int fVerbose;
0098     G4int fTwoJ1, fTwoJ2;
0099     G4int fLbar, fL;
0100     G4double fDelta;
0101     G4double kEps;
0102     G4PolynomialPDF kPolyPDF;
0103     G4LegendrePolynomial fgLegendrePolys;
0104 };
0105
0106
0107 #endif