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25 //
26 // -------------------------------------------------------------------
27 // GEANT4 Class file
28 //
29 // File name: G4PolarizationTransition
30 //
31 // Author: Jason Detwiler (jasondet@gmail.com)
32 //
33 // Creation date: Aug 2012
34 //
35 // Description:
36 // Stores and manipulates the statistical tensor describing the nuclear
37 // polarization (see Alder and Winther, "Electromagnetic Excitation" (1975),
38 // Appendix F). Functions are implemented for generating angular correlations
39 // in gamma decays, following Alder and Winther, Appendix G.
40 // This code assumes no polarization will be detected and uses eqs (17-20).
41 // Adding polarization would require using instead (13) and the more generic
42 // form of the statstical tensor after decay described by equation (6)
43 // Could be expanded to also generate e.g. gamma-beta and other
44 // correlations as well.
45 //
46 // -------------------------------------------------------------------
47
48 #ifndef G4POLARIZATIONTRANSITION_HH
49 #define G4POLARIZATIONTRANSITION_HH
50
51 #include "globals.hh"
52 #include "G4LegendrePolynomial.hh"
53 #include "G4PolynomialPDF.hh"
54 #include "G4Pow.hh"
55
56 class G4NuclearPolarization;
57
58 class G4PolarizationTransition
59 {
60 typedef std::vector< std::vector<G4complex> > POLAR;
61
62 public:
63 G4PolarizationTransition();
64 ~G4PolarizationTransition() = default;
65
66 void SampleGammaTransition(G4NuclearPolarization* np,
67 G4int twoJ1, G4int twoJ2,
68 G4int L0, G4int Lp, G4double mpRatio,
69 G4double& cosTheta, G4double& phi);
70
71 // generic static functions
72 G4double FCoefficient(G4int K, G4int L, G4int Lprime,
73 G4int twoJ2, G4int twoJ1) const;
74 G4double F3Coefficient(G4int K, G4int K2, G4int K1, G4int L,
75 G4int Lprime, G4int twoJ2, G4int twoJ1) const;
76
77 // transition-specific functions
78 G4double GammaTransFCoefficient(G4int K) const;
79 G4double GammaTransF3Coefficient(G4int K, G4int K2, G4int K1) const;
80
81 void DumpTransitionData(const POLAR& pol) const;
82
83 inline void SetVerbose(G4int val) { fVerbose = val; };
84
85 private:
86
87 G4PolarizationTransition(const G4PolarizationTransition &right) = delete;
88 const G4PolarizationTransition& operator=(const G4PolarizationTransition &right) = delete;
89
90 // Gamma angle generation and decay: call these functions in this order!
91 // All angles are in the same coordinate system: user may choose any axis
92 G4double GenerateGammaCosTheta(const POLAR&);
93 G4double GenerateGammaPhi(G4double& cosTheta, const POLAR&);
94
95 inline G4double LnFactorial(int k) const { return G4Pow::GetInstance()->logfactorial(k); }
96
97 G4int fVerbose;
98 G4int fTwoJ1, fTwoJ2;
99 G4int fLbar, fL;
100 G4double fDelta;
101 G4double kEps;
102 G4PolynomialPDF kPolyPDF;
103 G4LegendrePolynomial fgLegendrePolys;
104 };
105
106
107 #endif
108