Gabriele Cosmo
116 lines
4.3 KiB
C++
116 lines
4.3 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//---------------------------------------------------------------------------
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//
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// ClassName: G4AtomicFormFactor
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//
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// Description: Contains the function for the evaluation of the atomic form
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// factor. The tabulated data are available on IUCr website
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//
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// Class description:
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//
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// XXX
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//
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// 21-04-16, created by E.Bagli
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#ifndef G4ATOMICFORMFACTOR_HH
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#define G4ATOMICFORMFACTOR_HH 1
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#include "G4Exp.hh"
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#include "globals.hh"
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#include <map>
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#include <vector>
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class G4AtomicFormFactor
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{
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public:
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static G4AtomicFormFactor* GetManager()
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{
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if (s_G4AtomicFormFactorManager == nullptr) {
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s_G4AtomicFormFactorManager = new G4AtomicFormFactor();
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}
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return s_G4AtomicFormFactorManager;
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}
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G4double Get(G4double kScatteringVector, G4int Z, G4int charge = 0)
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{
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if (loadedIndex != GetIndex(Z, charge)) {
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LoadCoefficiencts(GetIndex(Z, charge));
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}
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G4double result = 0.;
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G4double kVecOn4PiSquared =
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(kScatteringVector / 1.e-7 / 3.1415926536) * 0.125; // (k/(4pi))/ angstrom
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kVecOn4PiSquared = kVecOn4PiSquared * kVecOn4PiSquared; // (k/(4pi))^2
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for (unsigned int i0 = 0; i0 < 4; i0++) {
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result += theCoefficients[i0 * 2] * G4Exp(-theCoefficients[i0 * 2 + 1] * kVecOn4PiSquared);
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}
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result += theCoefficients[8];
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return result;
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}
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protected:
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G4AtomicFormFactor();
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~G4AtomicFormFactor() = default;
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private:
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void InsertCoefficients(G4int index, const std::vector<G4double>& aDoubleVec)
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{
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theCoefficientsMap.insert(std::pair<G4int, std::vector<G4double>>(index, aDoubleVec));
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}
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// LoadCoefficiencts() method allows the evaluation of the atomic form
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// factor coefficients and the storage in theCoefficients.
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// If theCoefficients are already correct, no need to get new ones
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// Reference: International Tables for Crystallography (2006).
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// Vol. C, ch. 6.1, pp. 554-595
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// doi: 10.1107/97809553602060000600
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// Chapter 6.1. Intensity of diffracted intensities
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// IUCr Eq. 6.1.1.15, Coefficients Table 6.1.1.4
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void LoadCoefficiencts(G4int index)
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{
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loadedIndex = index;
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for (unsigned int i0 = 0; i0 < 9; i0++) {
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theCoefficients[i0] = theCoefficientsMap[index][i0];
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}
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}
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// Get() function gives back the Atomic Form Factor of the Z material
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inline G4int GetIndex(G4int Z, G4int charge = 0) { return Z * 100 + charge; }
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private:
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inline static G4AtomicFormFactor* s_G4AtomicFormFactorManager = nullptr;
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// theCoefficientsMap stores the coefficients for the form factor
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// calculations. It can be loaded only by LoadCoefficiencts()
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// and accessed by theCoefficients[].
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std::map<G4int, std::vector<G4double>> theCoefficientsMap;
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G4double theCoefficients[9];
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G4int loadedIndex;
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};
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#endif
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