Gabriele Cosmo
81 lines
2.8 KiB
C++
81 lines
2.8 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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//
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#ifndef G4FermiMomentum_h
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#define G4FermiMomentum_h 1
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#include "globals.hh"
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#include "G4ThreeVector.hh"
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#include "Randomize.hh"
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#include "G4Pow.hh"
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class G4FermiMomentum
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{
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public:
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G4FermiMomentum();
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~G4FermiMomentum();
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inline void Init(G4int anA, G4int aZ) {theA = anA; theZ = aZ;}
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inline G4double GetFermiMomentum(G4double density)
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{
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return constofpmax * cbrt(density * theA);
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}
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inline G4ThreeVector GetMomentum(G4double density,
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G4double maxMomentum=-1.)
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{
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if (maxMomentum < 0 ) maxMomentum=GetFermiMomentum(density);
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G4ThreeVector p;
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do {
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p=G4ThreeVector(2.*G4UniformRand()-1.,
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2.*G4UniformRand()-1.,
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2.*G4UniformRand()-1.);
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} while ( p.mag() > 1. ); /* Loop checking, 30-Oct-2015, G.Folger */
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return p*maxMomentum;
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}
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private:
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G4double cbrt(G4double x) { return G4Pow::GetInstance()->A13(x); }
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private:
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G4int theA;
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G4int theZ;
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// pmax= hbar * c * ( 3* pi**2 * rho )**(1/3) =
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// hbar * c * ( 3* pi**2 )**(1/3) * rho**(1/3)=
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// constofpmax * rho**(1/3)
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G4double constofpmax;
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};
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#endif
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