Gabriele Cosmo
125 lines
4.5 KiB
Plaintext
125 lines
4.5 KiB
Plaintext
//
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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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// $Id: G4DNARutherfordTotalCrossSectionPolicy.icc,v 1.2 2006/06/29 19:35:21 gunter Exp $
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// GEANT4 tag $Name: geant4-08-01 $
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//
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#ifdef G4DNARUTHERFORDTOTALCROSSSECTIONPOLICY_HH
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#include "G4Electron.hh"
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template <typename EnergyLimitsPolicy>
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const G4ParticleDefinition *G4DNARutherfordTotalCrossSectionPolicy<EnergyLimitsPolicy> :: IncomingParticleDefinition(void) const
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{
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return G4Electron::Electron();
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}
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template <typename EnergyLimitsPolicy>
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G4double G4DNARutherfordTotalCrossSectionPolicy<EnergyLimitsPolicy> :: TotalCrossSection(G4double k, G4int z) const
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{
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// pi * sigma_Ruth(K)
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// sigma_el(K) = --------------------
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// n(K) * (n(K) + 1)
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//
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// Where K is the electron non-relativistic kinetic energy
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// Cross section per water molecule
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if (k < EnergyLimitsPolicy::lowEnergyLimit)
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{
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if (EnergyLimitsPolicy::zeroBelowLowEnergyLimit)
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return 0;
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k=EnergyLimitsPolicy::lowEnergyLimit;
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}
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else if (k > EnergyLimitsPolicy::highEnergyLimit)
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{
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if (EnergyLimitsPolicy::zeroAboveHighEnergyLimit)
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return 0;
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k=EnergyLimitsPolicy::highEnergyLimit;
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}
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G4double n=ScreeningFactor(k,z);
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return (pi * RutherfordTotalCrossSection(k, z))/(n*(n+1.));
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}
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template <typename EnergyLimitsPolicy>
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G4double G4DNARutherfordTotalCrossSectionPolicy<EnergyLimitsPolicy> :: RutherfordTotalCrossSection(G4double k, G4int z) const
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{
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// e^4 / K + m_e c^2 \^2
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// sigma_Ruth(K) = Z (Z+1) -------------------- | --------------------- |
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// (4 pi epsilon_0)^2 \ K * (K + 2 m_e c^2) /
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//
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// Where K is the electron non-relativistic kinetic energy
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//
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// Nucl. Instr. Meth. 155 (1978) 145-156
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G4double length;
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length=(e_squared*(k+electron_mass_c2))/(4*pi*epsilon0*k*(k+2*electron_mass_c2));
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return static_cast<G4double>(z*(z+1))*length*length;
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}
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template <typename EnergyLimitsPolicy>
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G4double G4DNARutherfordTotalCrossSectionPolicy<EnergyLimitsPolicy> :: ScreeningFactor(G4double k, G4int z) const
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{
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//
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// alpha_1 + beta_1 ln(K/eV) constK Z^(2/3)
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// n(T) = -------------------------- -----------------
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// K/(m_e c^2) 2 + K/(m_e c^2)
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//
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// Where K is the electron non-relativistic kinetic energy
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//
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// n(T) > 0 for T < ~ 400 MeV
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//
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// Nucl. Instr. Meth. 155 (1978) 145-156
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const G4double alpha_1(1.64);
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const G4double beta_1(-0.0825);
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const G4double constK(1.7E-5);
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G4double numerator;
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numerator=(alpha_1+beta_1*std::log(k/eV))*constK*std::pow(static_cast<double>(z), 2./3.);
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k/=electron_mass_c2;
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G4double denominator;
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denominator=k*(2+k);
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return numerator/denominator;
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}
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#endif /* G4DNARUTHERFORDTOTALCROSSSECTIONPOLICY_HH */
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