| 1 | // |
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| 2 | // ******************************************************************** |
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| 3 | // * License and Disclaimer * |
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| 4 | // * * |
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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| 7 | // * conditions of the Geant4 Software License, included in the file * |
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| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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| 9 | // * include a list of copyright holders. * |
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| 10 | // * * |
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| 11 | // * Neither the authors of this software system, nor their employing * |
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| 12 | // * institutes,nor the agencies providing financial support for this * |
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| 13 | // * work make any representation or warranty, express or implied, * |
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| 14 | // * regarding this software system or assume any liability for its * |
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| 15 | // * use. Please see the license in the file LICENSE and URL above * |
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| 16 | // * for the full disclaimer and the limitation of liability. * |
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| 17 | // * * |
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| 18 | // * This code implementation is the result of the scientific and * |
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| 19 | // * technical work of the GEANT4 collaboration. * |
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| 20 | // * By using, copying, modifying or distributing the software (or * |
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| 21 | // * any work based on the software) you agree to acknowledge its * |
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| 22 | // * use in resulting scientific publications, and indicate your * |
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| 23 | // * acceptance of all terms of the Geant4 Software license. * |
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| 24 | // ******************************************************************** |
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| 25 | // |
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| 26 | // |
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| 27 | // |
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| 28 | #ifndef G4NuclearFermiDensity_h |
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| 29 | #define G4NuclearFermiDensity_h 1 |
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| 30 | |
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| 31 | #include "globals.hh" |
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| 32 | #include "G4ThreeVector.hh" |
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| 33 | #include "G4VNuclearDensity.hh" |
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| 34 | |
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| 35 | #include <CLHEP/Units/PhysicalConstants.h> // pi, fermi,.. |
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| 36 | #include <cmath> // pow |
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| 37 | |
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| 38 | class G4NuclearFermiDensity : public G4VNuclearDensity |
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| 39 | { |
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| 40 | |
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| 41 | public: |
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| 42 | G4NuclearFermiDensity(G4int anA, G4int aZ); |
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| 43 | ~G4NuclearFermiDensity(); |
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| 44 | |
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| 45 | G4double GetRelativeDensity(const G4ThreeVector & aPosition) const |
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| 46 | { |
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| 47 | return 1./(1.+std::exp((aPosition.mag()-theR)/a)); |
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| 48 | } |
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| 49 | |
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| 50 | G4double GetRadius(const G4double maxRelativeDenisty) const |
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| 51 | { |
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| 52 | return (maxRelativeDenisty>0 && maxRelativeDenisty <= 1 ) ? |
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| 53 | (theR + a*std::log((1-maxRelativeDenisty+std::exp(-1*theR/a))/maxRelativeDenisty)) : DBL_MAX; |
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| 54 | } |
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| 55 | |
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| 56 | G4double GetDeriv(const G4ThreeVector & aPosition) const |
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| 57 | { |
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| 58 | G4double currentR=aPosition.mag(); |
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| 59 | if (currentR > 40*theR ) {return 0;} |
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| 60 | else return -std::exp((currentR-theR)/a) * sqr(GetDensity(aPosition)) / (a*Getrho0()); |
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| 61 | } |
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| 62 | |
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| 63 | private: |
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| 64 | |
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| 65 | G4int theA; |
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| 66 | G4int theZ; |
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| 67 | G4double theR; // Nuclear Radius |
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| 68 | const G4double a; // Determines the nuclear surface thickness |
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| 69 | |
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| 70 | }; |
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| 71 | |
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| 72 | #endif |
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| 73 | |
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