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0001 // 0002 // ******************************************************************** 0003 // * License and Disclaimer * 0004 // * * 0005 // * The Geant4 software is copyright of the Copyright Holders of * 0006 // * the Geant4 Collaboration. It is provided under the terms and * 0007 // * conditions of the Geant4 Software License, included in the file * 0008 // * LICENSE and available at http://cern.ch/geant4/license . These * 0009 // * include a list of copyright holders. * 0010 // * * 0011 // * Neither the authors of this software system, nor their employing * 0012 // * institutes,nor the agencies providing financial support for this * 0013 // * work make any representation or warranty, express or implied, * 0014 // * regarding this software system or assume any liability for its * 0015 // * use. Please see the license in the file LICENSE and URL above * 0016 // * for the full disclaimer and the limitation of liability. * 0017 // * * 0018 // * This code implementation is the result of the scientific and * 0019 // * technical work of the GEANT4 collaboration. * 0020 // * By using, copying, modifying or distributing the software (or * 0021 // * any work based on the software) you agree to acknowledge its * 0022 // * use in resulting scientific publications, and indicate your * 0023 // * acceptance of all terms of the Geant4 Software license. * 0024 // ******************************************************************** 0025 // 0026 // 0027 // ----------------------------------------------------------------------------- 0028 // 0029 // GEANT4 Class header file 0030 // 0031 // File name: G4GoudsmitSaundersonTable 0032 // 0033 // Author: Mihaly Novak / (Omrane Kadri) 0034 // 0035 // Creation date: 20.02.2009 0036 // 0037 // Class description: 0038 // Class to handle multiple scattering angular distributions precomputed by 0039 // using Kawrakow-Bielajew Goudsmit-Saunderson MSC model based on the screened 0040 // Rutherford DCS for elastic scattering of electrons/positrons [1,2]. This 0041 // class is used by G4GoudsmitSaundersonMscModel to sample the angular 0042 // deflection of electrons/positrons after travelling a given path. 0043 // 0044 // Modifications: 0045 // 04.03.2009 V.Ivanchenko cleanup and format according to Geant4 EM style 0046 // 18.05.2015 M. Novak This class has been completely replaced (only the original 0047 // class name was kept; class description was also inserted): 0048 // A new version of Kawrakow-Bielajew Goudsmit-Saunderson MSC model 0049 // based on the screened Rutherford DCS for elastic scattering of 0050 // electrons/positrons has been introduced[1,2]. The corresponding MSC 0051 // angular distributions over a 2D parameter grid have been recomputed 0052 // and the CDFs are now stored in a variable transformed (smooth) form 0053 // together with the corresponding rational interpolation parameters. 0054 // The new version is several times faster, more robust and accurate 0055 // compared to the earlier version (G4GoudsmitSaundersonMscModel class 0056 // that use these data has been also completely replaced) 0057 // [1] A.F.Bielajew, NIMB, 111 (1996) 195-208 0058 // [2] I.Kawrakow, A.F.Bielajew, NIMB 134(1998) 325-336 0059 // 28.04.2017 M. Novak: the GS angular distributions has been recomputed, the 0060 // data size has been reduced from 16 MB down to 5 MB by using a new 0061 // representation, the class has been modified significantly due to 0062 // this new data representation. 0063 // 23.08.2017 M. Novak: Added funtionality to handle Mott-correction to the 0064 // base GS angular distributions and some other factors (screening 0065 // parameter, first and second moments) when Mott-correction is 0066 // activated in the GS-MSC model. 0067 // 26.10.2025 M. Novak: added the related technical note as the proper reference. 0068 // 0069 // References: 0070 // M. Novak: https://arxiv.org/abs/2410.13361 0071 // 0072 // ----------------------------------------------------------------------------- 0073 0074 0075 #ifndef G4GoudsmitSaundersonTable_h 0076 #define G4GoudsmitSaundersonTable_h 1 0077 0078 #include <vector> 0079 0080 #include "G4Types.hh" 0081 0082 class G4GSMottCorrection; 0083 class G4MaterialCutsCouple; 0084 0085 class G4GoudsmitSaundersonTable { 0086 0087 public: 0088 G4GoudsmitSaundersonTable(G4bool iselectron); 0089 ~G4GoudsmitSaundersonTable(); 0090 0091 void Initialise(G4double lownergylimit, G4double highenergylimit); 0092 0093 // structure to store one GS transformed angular distribution (for a given s/lambda_el,s/lambda_elG1) 0094 struct GSMSCAngularDtr { 0095 G4int fNumData; // # of data points 0096 G4double *fUValues; // array of transformed variables 0097 G4double *fParamA; // array of interpolation parameters a 0098 G4double *fParamB; // array of interpolation parameters b 0099 }; 0100 0101 void LoadMSCData(); 0102 0103 G4bool Sampling(G4double lambdaval, G4double qval, G4double scra, 0104 G4double &cost, G4double &sint, G4double lekin, 0105 G4double beta2, G4int matindx, GSMSCAngularDtr **gsDtr, 0106 G4int &mcekini, G4int &mcdelti, G4double &transfPar, 0107 G4bool isfirst); 0108 0109 G4double SampleCosTheta(G4double lambdaval, G4double qval, G4double scra, 0110 G4double lekin, G4double beta2, G4int matindx, 0111 GSMSCAngularDtr **gsDtr, G4int &mcekini, G4int &mcdelti, 0112 G4double &transfPar, G4bool isfirst); 0113 0114 G4double SampleGSSRCosTheta(const GSMSCAngularDtr* gsDrt, G4double transfpar); 0115 0116 G4double SingleScattering(G4double lambdaval, G4double scra, G4double lekin, 0117 G4double beta2, G4int matindx); 0118 0119 GSMSCAngularDtr* GetGSAngularDtr(G4double scra, G4double &lambdaval, 0120 G4double &qval, G4double &transfpar); 0121 0122 // material dependent MSC parameters (computed at initialisation) regarding 0123 // Moliere's screening parameter 0124 G4double GetMoliereBc(G4int matindx) { return gMoliereBc[matindx]; } 0125 0126 G4double GetMoliereXc2(G4int matindx) { return gMoliereXc2[matindx]; } 0127 0128 void GetMottCorrectionFactors(G4double logekin, G4double beta2, 0129 G4int matindx, G4double &mcToScr, 0130 G4double &mcToQ1, G4double &mcToG2PerG1); 0131 0132 // set option to activate/inactivate Mott-correction 0133 void SetOptionMottCorrection(G4bool val) { fIsMottCorrection = val; } 0134 // set option to activate/inactivate PWA-correction 0135 void SetOptionPWACorrection(G4bool val) { fIsPWACorrection = val; } 0136 0137 // this method returns with the scattering power correction (to avoid double counting of sub-threshold deflections) 0138 // interpolated from tables prepared at initialisation 0139 G4double ComputeScatteringPowerCorrection(const G4MaterialCutsCouple *matcut, G4double ekin); 0140 0141 void InitSCPCorrection(); 0142 0143 private: 0144 // initialisation of material dependent Moliere's MSC parameters 0145 void InitMoliereMSCParams(); 0146 0147 0148 private: 0149 static G4bool gIsInitialised; // are the precomputed angular distributions already loaded in? 0150 static constexpr G4int gLAMBNUM = 64; // # L=s/lambda_el in [fLAMBMIN,fLAMBMAX] 0151 static constexpr G4int gQNUM1 = 15; // # Q=s/lambda_el G1 in [fQMIN1,fQMAX1] in the 1-st Q grid 0152 static constexpr G4int gQNUM2 = 32; // # Q=s/lambda_el G1 in [fQMIN2,fQMAX2] in the 2-nd Q grid 0153 static constexpr G4int gNUMSCR1 = 201; // # of screening parameters in the A(G1) function 0154 static constexpr G4int gNUMSCR2 = 51; // # of screening parameters in the A(G1) function 0155 static constexpr G4double gLAMBMIN = 1.0; // minimum s/lambda_el 0156 static constexpr G4double gLAMBMAX = 100000.0; // maximum s/lambda_el 0157 static constexpr G4double gQMIN1 = 0.001; // minimum s/lambda_el G1 in the 1-st Q grid 0158 static constexpr G4double gQMAX1 = 0.99; // maximum s/lambda_el G1 in the 1-st Q grid 0159 static constexpr G4double gQMIN2 = 0.99; // minimum s/lambda_el G1 in the 2-nd Q grid 0160 static constexpr G4double gQMAX2 = 7.99; // maximum s/lambda_el G1 in the 2-nd Q grid 0161 // 0162 G4bool fIsElectron; // GS-table for e- (for e+ otherwise) 0163 G4bool fIsMottCorrection; // flag to indicate if Mott-correction was requested to be used 0164 G4bool fIsPWACorrection; // flag to indicate is PWA corrections were requested to be used 0165 G4double fLogLambda0; // ln(gLAMBMIN) 0166 G4double fLogDeltaLambda; // ln(gLAMBMAX/gLAMBMIN)/(gLAMBNUM-1) 0167 G4double fInvLogDeltaLambda; // 1/[ln(gLAMBMAX/gLAMBMIN)/(gLAMBNUM-1)] 0168 G4double fInvDeltaQ1; // 1/[(gQMAX1-gQMIN1)/(gQNUM1-1)] 0169 G4double fDeltaQ2; // [(gQMAX2-gQMIN2)/(gQNUM2-1)] 0170 G4double fInvDeltaQ2; // 1/[(gQMAX2-gQMIN2)/(gQNUM2-1)] 0171 // 0172 G4double fLowEnergyLimit; 0173 G4double fHighEnergyLimit; 0174 // 0175 int fNumSPCEbinPerDec; // scattering power correction energy grid bins per decade 0176 struct SCPCorrection { 0177 bool fIsUse; // 0178 double fPrCut; // sec. e- production cut energy 0179 double fLEmin; // log min energy 0180 double fILDel; // inverse log delta kinetic energy 0181 //std::vector<double> fVEkin; // scattering power correction energies 0182 std::vector<double> fVSCPC; // scattering power correction vector 0183 }; 0184 std::vector<SCPCorrection*> fSCPCPerMatCuts; 0185 0186 0187 // vector to store all GS transformed angular distributions (cumputed based on the Screened-Rutherford DCS) 0188 static std::vector<GSMSCAngularDtr*> gGSMSCAngularDistributions1; 0189 static std::vector<GSMSCAngularDtr*> gGSMSCAngularDistributions2; 0190 0191 //@{ 0192 /** Precomputed \f$ b_lambda_{c} $\f and \f$ \chi_c^{2} $\f material dependent 0193 * Moliere parameters that can be used to compute the screening parameter, 0194 * the elastic scattering cross section (or \f$ \lambda_{e} $\f) under the 0195 * screened Rutherford cross section approximation. (These are used in 0196 * G4GoudsmitSaundersonMscModel if fgIsUsePWATotalXsecData is FALSE.) 0197 */ 0198 static std::vector<double> gMoliereBc; 0199 static std::vector<double> gMoliereXc2; 0200 // 0201 // 0202 G4GSMottCorrection *fMottCorrection; 0203 }; 0204 0205 #endif
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