include/Geant4/G4AtomicFormFactor.hh

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 // ClassName:   G4AtomicFormFactor
0029 //
0030 // Description: Contains the function for the evaluation of the atomic form
0031 //              factor. The tabulated data are available on IUCr website
0032 //
0033 // Class description:
0034 //
0035 // XXX
0036 //
0037 // 21-04-16, created by E.Bagli
0038
0039 #ifndef G4ATOMICFORMFACTOR_HH
0040 #define G4ATOMICFORMFACTOR_HH 1
0041
0042 #include "G4Exp.hh"
0043 #include "globals.hh"
0044
0045 #include <map>
0046 #include <vector>
0047
0048 class G4AtomicFormFactor
0049 {
0050  public:
0051   static G4AtomicFormFactor* GetManager()
0052   {
0053     if (s_G4AtomicFormFactorManager == nullptr) {
0054       s_G4AtomicFormFactorManager = new G4AtomicFormFactor();
0055     }
0056     return s_G4AtomicFormFactorManager;
0057   }
0058
0059   G4double Get(G4double kScatteringVector, G4int Z, G4int charge = 0)
0060   {
0061     if (loadedIndex != GetIndex(Z, charge)) {
0062       LoadCoefficiencts(GetIndex(Z, charge));
0063     }
0064     G4double result = 0.;
0065     G4double kVecOn4PiSquared =
0066       (kScatteringVector / 1.e-7 / 3.1415926536) * 0.125;  // (k/(4pi))/   angstrom
0067     kVecOn4PiSquared = kVecOn4PiSquared * kVecOn4PiSquared;  // (k/(4pi))^2
0068
0069     for (unsigned int i0 = 0; i0 < 4; i0++) {
0070       result += theCoefficients[i0 * 2] * G4Exp(-theCoefficients[i0 * 2 + 1] * kVecOn4PiSquared);
0071     }
0072     result += theCoefficients[8];
0073     return result;
0074   }
0075
0076  protected:
0077   G4AtomicFormFactor();
0078   ~G4AtomicFormFactor() = default;
0079
0080  private:
0081   void InsertCoefficients(G4int index, const std::vector<G4double>& aDoubleVec)
0082   {
0083     theCoefficientsMap.insert(std::pair<G4int, std::vector<G4double>>(index, aDoubleVec));
0084   }
0085
0086   // LoadCoefficiencts() method allows the evaluation of the atomic form
0087   // factor coefficients and the storage in theCoefficients.
0088   // If theCoefficients are already correct, no need to get new ones
0089   // Reference: International Tables for Crystallography (2006).
0090   // Vol. C, ch. 6.1, pp. 554-595
0091   // doi: 10.1107/97809553602060000600
0092   // Chapter 6.1. Intensity of diffracted intensities
0093   // IUCr Eq. 6.1.1.15, Coefficients Table 6.1.1.4
0094   void LoadCoefficiencts(G4int index)
0095   {
0096     loadedIndex = index;
0097     for (unsigned int i0 = 0; i0 < 9; i0++) {
0098       theCoefficients[i0] = theCoefficientsMap[index][i0];
0099     }
0100   }
0101
0102   // Get() function gives back the Atomic Form Factor of the Z material
0103   inline G4int GetIndex(G4int Z, G4int charge = 0) { return Z * 100 + charge; }
0104
0105  private:
0106   inline static G4AtomicFormFactor* s_G4AtomicFormFactorManager = nullptr;
0107
0108   // theCoefficientsMap stores the coefficients for the form factor
0109   // calculations. It can be loaded only by LoadCoefficiencts()
0110   // and accessed by theCoefficients[].
0111   std::map<G4int, std::vector<G4double>> theCoefficientsMap;
0112   G4double theCoefficients[9];
0113   G4int loadedIndex;
0114 };
0115 #endif