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26 //
27 // -----------------------------------------------------------------------------
28 //
29 // GEANT4 Class header file
30 //
31 // File name: G4GoudsmitSaundersonTable
32 //
33 // Author: Mihaly Novak / (Omrane Kadri)
34 //
35 // Creation date: 20.02.2009
36 //
37 // Class description:
38 // Class to handle multiple scattering angular distributions precomputed by
39 // using Kawrakow-Bielajew Goudsmit-Saunderson MSC model based on the screened
40 // Rutherford DCS for elastic scattering of electrons/positrons [1,2]. This
41 // class is used by G4GoudsmitSaundersonMscModel to sample the angular
42 // deflection of electrons/positrons after travelling a given path.
43 //
44 // Modifications:
45 // 04.03.2009 V.Ivanchenko cleanup and format according to Geant4 EM style
46 // 18.05.2015 M. Novak This class has been completely replaced (only the original
47 // class name was kept; class description was also inserted):
48 // A new version of Kawrakow-Bielajew Goudsmit-Saunderson MSC model
49 // based on the screened Rutherford DCS for elastic scattering of
50 // electrons/positrons has been introduced[1,2]. The corresponding MSC
51 // angular distributions over a 2D parameter grid have been recomputed
52 // and the CDFs are now stored in a variable transformed (smooth) form
53 // together with the corresponding rational interpolation parameters.
54 // The new version is several times faster, more robust and accurate
55 // compared to the earlier version (G4GoudsmitSaundersonMscModel class
56 // that use these data has been also completely replaced)
57 // 28.04.2017 M. Novak: the GS angular distributions has been recomputed, the
58 // data size has been reduced from 16 MB down to 5 MB by using a new
59 // representation, the class has been modified significantly due to
60 // this new data representation.
61 // 23.08.2017 M. Novak: Added funtionality to handle Mott-correction to the
62 // base GS angular distributions and some other factors (screening
63 // parameter, first and second moments) when Mott-correction is
64 // activated in the GS-MSC model.
65 //
66 // References:
67 // [1] A.F.Bielajew, NIMB, 111 (1996) 195-208
68 // [2] I.Kawrakow, A.F.Bielajew, NIMB 134(1998) 325-336
69 //
70 // -----------------------------------------------------------------------------
71
72
73 #ifndef G4GoudsmitSaundersonTable_h
74 #define G4GoudsmitSaundersonTable_h 1
75
76 #include <vector>
77
78 #include "G4Types.hh"
79
80 class G4GSMottCorrection;
81 class G4MaterialCutsCouple;
82
83 class G4GoudsmitSaundersonTable {
84
85 public:
86 G4GoudsmitSaundersonTable(G4bool iselectron);
87 ~G4GoudsmitSaundersonTable();
88
89 void Initialise(G4double lownergylimit, G4double highenergylimit);
90
91 // structure to store one GS transformed angular distribution (for a given s/lambda_el,s/lambda_elG1)
92 struct GSMSCAngularDtr {
93 G4int fNumData; // # of data points
94 G4double *fUValues; // array of transformed variables
95 G4double *fParamA; // array of interpolation parameters a
96 G4double *fParamB; // array of interpolation parameters b
97 };
98
99 void LoadMSCData();
100
101 G4bool Sampling(G4double lambdaval, G4double qval, G4double scra,
102 G4double &cost, G4double &sint, G4double lekin,
103 G4double beta2, G4int matindx, GSMSCAngularDtr **gsDtr,
104 G4int &mcekini, G4int &mcdelti, G4double &transfPar,
105 G4bool isfirst);
106
107 G4double SampleCosTheta(G4double lambdaval, G4double qval, G4double scra,
108 G4double lekin, G4double beta2, G4int matindx,
109 GSMSCAngularDtr **gsDtr, G4int &mcekini, G4int &mcdelti,
110 G4double &transfPar, G4bool isfirst);
111
112 G4double SampleGSSRCosTheta(const GSMSCAngularDtr* gsDrt, G4double transfpar);
113
114 G4double SingleScattering(G4double lambdaval, G4double scra, G4double lekin,
115 G4double beta2, G4int matindx);
116
117 GSMSCAngularDtr* GetGSAngularDtr(G4double scra, G4double &lambdaval,
118 G4double &qval, G4double &transfpar);
119
120 // material dependent MSC parameters (computed at initialisation) regarding
121 // Moliere's screening parameter
122 G4double GetMoliereBc(G4int matindx) { return gMoliereBc[matindx]; }
123
124 G4double GetMoliereXc2(G4int matindx) { return gMoliereXc2[matindx]; }
125
126 void GetMottCorrectionFactors(G4double logekin, G4double beta2,
127 G4int matindx, G4double &mcToScr,
128 G4double &mcToQ1, G4double &mcToG2PerG1);
129
130 // set option to activate/inactivate Mott-correction
131 void SetOptionMottCorrection(G4bool val) { fIsMottCorrection = val; }
132 // set option to activate/inactivate PWA-correction
133 void SetOptionPWACorrection(G4bool val) { fIsPWACorrection = val; }
134
135 // this method returns with the scattering power correction (to avoid double counting of sub-threshold deflections)
136 // interpolated from tables prepared at initialisation
137 G4double ComputeScatteringPowerCorrection(const G4MaterialCutsCouple *matcut, G4double ekin);
138
139 void InitSCPCorrection();
140
141 private:
142 // initialisation of material dependent Moliere's MSC parameters
143 void InitMoliereMSCParams();
144
145
146 private:
147 static G4bool gIsInitialised; // are the precomputed angular distributions already loaded in?
148 static constexpr G4int gLAMBNUM = 64; // # L=s/lambda_el in [fLAMBMIN,fLAMBMAX]
149 static constexpr G4int gQNUM1 = 15; // # Q=s/lambda_el G1 in [fQMIN1,fQMAX1] in the 1-st Q grid
150 static constexpr G4int gQNUM2 = 32; // # Q=s/lambda_el G1 in [fQMIN2,fQMAX2] in the 2-nd Q grid
151 static constexpr G4int gNUMSCR1 = 201; // # of screening parameters in the A(G1) function
152 static constexpr G4int gNUMSCR2 = 51; // # of screening parameters in the A(G1) function
153 static constexpr G4double gLAMBMIN = 1.0; // minimum s/lambda_el
154 static constexpr G4double gLAMBMAX = 100000.0; // maximum s/lambda_el
155 static constexpr G4double gQMIN1 = 0.001; // minimum s/lambda_el G1 in the 1-st Q grid
156 static constexpr G4double gQMAX1 = 0.99; // maximum s/lambda_el G1 in the 1-st Q grid
157 static constexpr G4double gQMIN2 = 0.99; // minimum s/lambda_el G1 in the 2-nd Q grid
158 static constexpr G4double gQMAX2 = 7.99; // maximum s/lambda_el G1 in the 2-nd Q grid
159 //
160 G4bool fIsElectron; // GS-table for e- (for e+ otherwise)
161 G4bool fIsMottCorrection; // flag to indicate if Mott-correction was requested to be used
162 G4bool fIsPWACorrection; // flag to indicate is PWA corrections were requested to be used
163 G4double fLogLambda0; // ln(gLAMBMIN)
164 G4double fLogDeltaLambda; // ln(gLAMBMAX/gLAMBMIN)/(gLAMBNUM-1)
165 G4double fInvLogDeltaLambda; // 1/[ln(gLAMBMAX/gLAMBMIN)/(gLAMBNUM-1)]
166 G4double fInvDeltaQ1; // 1/[(gQMAX1-gQMIN1)/(gQNUM1-1)]
167 G4double fDeltaQ2; // [(gQMAX2-gQMIN2)/(gQNUM2-1)]
168 G4double fInvDeltaQ2; // 1/[(gQMAX2-gQMIN2)/(gQNUM2-1)]
169 //
170 G4double fLowEnergyLimit;
171 G4double fHighEnergyLimit;
172 //
173 int fNumSPCEbinPerDec; // scattering power correction energy grid bins per decade
174 struct SCPCorrection {
175 bool fIsUse; //
176 double fPrCut; // sec. e- production cut energy
177 double fLEmin; // log min energy
178 double fILDel; // inverse log delta kinetic energy
179 //std::vector<double> fVEkin; // scattering power correction energies
180 std::vector<double> fVSCPC; // scattering power correction vector
181 };
182 std::vector<SCPCorrection*> fSCPCPerMatCuts;
183
184
185 // vector to store all GS transformed angular distributions (cumputed based on the Screened-Rutherford DCS)
186 static std::vector<GSMSCAngularDtr*> gGSMSCAngularDistributions1;
187 static std::vector<GSMSCAngularDtr*> gGSMSCAngularDistributions2;
188
189 //@{
190 /** Precomputed \f$ b_lambda_{c} $\f and \f$ \chi_c^{2} $\f material dependent
191 * Moliere parameters that can be used to compute the screening parameter,
192 * the elastic scattering cross section (or \f$ \lambda_{e} $\f) under the
193 * screened Rutherford cross section approximation. (These are used in
194 * G4GoudsmitSaundersonMscModel if fgIsUsePWATotalXsecData is FALSE.)
195 */
196 static std::vector<double> gMoliereBc;
197 static std::vector<double> gMoliereXc2;
198 //
199 //
200 G4GSMottCorrection *fMottCorrection;
201 };
202
203 #endif
204