| 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 G4FermiMomentum_h |
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| 29 | #define G4FermiMomentum_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 "Randomize.hh" |
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| 34 | |
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| 35 | class G4FermiMomentum |
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| 36 | { |
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| 37 | |
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| 38 | public: |
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| 39 | G4FermiMomentum(); |
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| 40 | ~G4FermiMomentum(); |
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| 41 | |
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| 42 | inline void Init(G4double anA, G4double aZ) {theA = anA; theZ = aZ;} |
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| 43 | |
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| 44 | inline G4double GetFermiMomentum(G4double density) |
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| 45 | { |
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| 46 | return constofpmax * cbrt(density * theA); |
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| 47 | } |
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| 48 | |
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| 49 | inline G4ThreeVector GetMomentum(G4double density, |
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| 50 | G4double maxMomentum=-1.) |
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| 51 | { |
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| 52 | if (maxMomentum < 0 ) maxMomentum=GetFermiMomentum(density); |
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| 53 | G4ThreeVector p; |
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| 54 | |
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| 55 | do { |
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| 56 | p=G4ThreeVector(2.*G4UniformRand()-1., |
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| 57 | 2.*G4UniformRand()-1., |
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| 58 | 2.*G4UniformRand()-1.); |
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| 59 | } while ( p.mag() > 1. ); |
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| 60 | return p*maxMomentum; |
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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 | G4double cbrt(G4double x) { return std::pow(x,1./3.); } |
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| 66 | |
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| 67 | private: |
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| 68 | |
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| 69 | G4double theA; |
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| 70 | G4double theZ; |
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| 71 | // pmax= hbar * c * ( 3* pi**2 * rho )**(1/3) = |
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| 72 | // hbar * c * ( 3* pi**2 )**(1/3) * rho**(1/3)= |
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| 73 | // constofpmax * rho**(1/3) |
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| 74 | G4double constofpmax; |
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| 75 | |
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| 76 | }; |
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| 77 | |
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| 78 | #endif |
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| 79 | |
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