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Please see the license in the file LICENSE and URL above * // * for the full disclaimer and the limitation of liability. * // * * // * This code implementation is the result of the scientific and * // * technical work of the GEANT4 collaboration. * // * By using, copying, modifying or distributing the software (or * // * any work based on the software) you agree to acknowledge its * // * use in resulting scientific publications, and indicate your * // * acceptance of all terms of the Geant4 Software license. * // ******************************************************************** // // // ----------------------------------------------------------------------------- // // GEANT4 Class header file // // File name: G4GoudsmitSaundersonTable // // Author: Mihaly Novak / (Omrane Kadri) // // Creation date: 20.02.2009 // // Class description: // Class to handle multiple scattering angular distributions precomputed by // using Kawrakow-Bielajew Goudsmit-Saunderson MSC model based on the screened // Rutherford DCS for elastic scattering of electrons/positrons [1,2]. This // class is used by G4GoudsmitSaundersonMscModel to sample the angular // deflection of electrons/positrons after travelling a given path. // // Modifications: // 04.03.2009 V.Ivanchenko cleanup and format according to Geant4 EM style // 18.05.2015 M. Novak This class has been completely replaced (only the original // class name was kept; class description was also inserted): // A new version of Kawrakow-Bielajew Goudsmit-Saunderson MSC model // based on the screened Rutherford DCS for elastic scattering of // electrons/positrons has been introduced[1,2]. The corresponding MSC // angular distributions over a 2D parameter grid have been recomputed // and the CDFs are now stored in a variable transformed (smooth) form // together with the corresponding rational interpolation parameters. // The new version is several times faster, more robust and accurate // compared to the earlier version (G4GoudsmitSaundersonMscModel class // that use these data has been also completely replaced) // [1] A.F.Bielajew, NIMB, 111 (1996) 195-208 // [2] I.Kawrakow, A.F.Bielajew, NIMB 134(1998) 325-336 // 28.04.2017 M. Novak: the GS angular distributions has been recomputed, the // data size has been reduced from 16 MB down to 5 MB by using a new // representation, the class has been modified significantly due to // this new data representation. // 23.08.2017 M. Novak: Added funtionality to handle Mott-correction to the // base GS angular distributions and some other factors (screening // parameter, first and second moments) when Mott-correction is // activated in the GS-MSC model. // 26.10.2025 M. Novak: added the related technical note as the proper reference. // // References: // M. Novak: https://arxiv.org/abs/2410.13361 // // ----------------------------------------------------------------------------- #ifndef G4GoudsmitSaundersonTable_h #define G4GoudsmitSaundersonTable_h 1 #include #include "G4Types.hh" class G4GSMottCorrection; class G4MaterialCutsCouple; class G4GoudsmitSaundersonTable { public: G4GoudsmitSaundersonTable(G4bool iselectron); ~G4GoudsmitSaundersonTable(); void Initialise(G4double lownergylimit, G4double highenergylimit); // structure to store one GS transformed angular distribution (for a given s/lambda_el,s/lambda_elG1) struct GSMSCAngularDtr { G4int fNumData; // # of data points G4double *fUValues; // array of transformed variables G4double *fParamA; // array of interpolation parameters a G4double *fParamB; // array of interpolation parameters b }; void LoadMSCData(); G4bool Sampling(G4double lambdaval, G4double qval, G4double scra, G4double &cost, G4double &sint, G4double lekin, G4double beta2, G4int matindx, GSMSCAngularDtr **gsDtr, G4int &mcekini, G4int &mcdelti, G4double &transfPar, G4bool isfirst); G4double SampleCosTheta(G4double lambdaval, G4double qval, G4double scra, G4double lekin, G4double beta2, G4int matindx, GSMSCAngularDtr **gsDtr, G4int &mcekini, G4int &mcdelti, G4double &transfPar, G4bool isfirst); G4double SampleGSSRCosTheta(const GSMSCAngularDtr* gsDrt, G4double transfpar); G4double SingleScattering(G4double lambdaval, G4double scra, G4double lekin, G4double beta2, G4int matindx); GSMSCAngularDtr* GetGSAngularDtr(G4double scra, G4double &lambdaval, G4double &qval, G4double &transfpar); // material dependent MSC parameters (computed at initialisation) regarding // Moliere's screening parameter G4double GetMoliereBc(G4int matindx) { return gMoliereBc[matindx]; } G4double GetMoliereXc2(G4int matindx) { return gMoliereXc2[matindx]; } void GetMottCorrectionFactors(G4double logekin, G4double beta2, G4int matindx, G4double &mcToScr, G4double &mcToQ1, G4double &mcToG2PerG1); // set option to activate/inactivate Mott-correction void SetOptionMottCorrection(G4bool val) { fIsMottCorrection = val; } // set option to activate/inactivate PWA-correction void SetOptionPWACorrection(G4bool val) { fIsPWACorrection = val; } // this method returns with the scattering power correction (to avoid double counting of sub-threshold deflections) // interpolated from tables prepared at initialisation G4double ComputeScatteringPowerCorrection(const G4MaterialCutsCouple *matcut, G4double ekin); void InitSCPCorrection(); private: // initialisation of material dependent Moliere's MSC parameters void InitMoliereMSCParams(); private: static G4bool gIsInitialised; // are the precomputed angular distributions already loaded in? static constexpr G4int gLAMBNUM = 64; // # L=s/lambda_el in [fLAMBMIN,fLAMBMAX] static constexpr G4int gQNUM1 = 15; // # Q=s/lambda_el G1 in [fQMIN1,fQMAX1] in the 1-st Q grid static constexpr G4int gQNUM2 = 32; // # Q=s/lambda_el G1 in [fQMIN2,fQMAX2] in the 2-nd Q grid static constexpr G4int gNUMSCR1 = 201; // # of screening parameters in the A(G1) function static constexpr G4int gNUMSCR2 = 51; // # of screening parameters in the A(G1) function static constexpr G4double gLAMBMIN = 1.0; // minimum s/lambda_el static constexpr G4double gLAMBMAX = 100000.0; // maximum s/lambda_el static constexpr G4double gQMIN1 = 0.001; // minimum s/lambda_el G1 in the 1-st Q grid static constexpr G4double gQMAX1 = 0.99; // maximum s/lambda_el G1 in the 1-st Q grid static constexpr G4double gQMIN2 = 0.99; // minimum s/lambda_el G1 in the 2-nd Q grid static constexpr G4double gQMAX2 = 7.99; // maximum s/lambda_el G1 in the 2-nd Q grid // G4bool fIsElectron; // GS-table for e- (for e+ otherwise) G4bool fIsMottCorrection; // flag to indicate if Mott-correction was requested to be used G4bool fIsPWACorrection; // flag to indicate is PWA corrections were requested to be used G4double fLogLambda0; // ln(gLAMBMIN) G4double fLogDeltaLambda; // ln(gLAMBMAX/gLAMBMIN)/(gLAMBNUM-1) G4double fInvLogDeltaLambda; // 1/[ln(gLAMBMAX/gLAMBMIN)/(gLAMBNUM-1)] G4double fInvDeltaQ1; // 1/[(gQMAX1-gQMIN1)/(gQNUM1-1)] G4double fDeltaQ2; // [(gQMAX2-gQMIN2)/(gQNUM2-1)] G4double fInvDeltaQ2; // 1/[(gQMAX2-gQMIN2)/(gQNUM2-1)] // G4double fLowEnergyLimit; G4double fHighEnergyLimit; // int fNumSPCEbinPerDec; // scattering power correction energy grid bins per decade struct SCPCorrection { bool fIsUse; // double fPrCut; // sec. e- production cut energy double fLEmin; // log min energy double fILDel; // inverse log delta kinetic energy //std::vector fVEkin; // scattering power correction energies std::vector fVSCPC; // scattering power correction vector }; std::vector fSCPCPerMatCuts; // vector to store all GS transformed angular distributions (cumputed based on the Screened-Rutherford DCS) static std::vector gGSMSCAngularDistributions1; static std::vector gGSMSCAngularDistributions2; //@{ /** Precomputed \f$ b_lambda_{c} $\f and \f$ \chi_c^{2} $\f material dependent * Moliere parameters that can be used to compute the screening parameter, * the elastic scattering cross section (or \f$ \lambda_{e} $\f) under the * screened Rutherford cross section approximation. (These are used in * G4GoudsmitSaundersonMscModel if fgIsUsePWATotalXsecData is FALSE.) */ static std::vector gMoliereBc; static std::vector gMoliereXc2; // // G4GSMottCorrection *fMottCorrection; }; #endif