Gabriele Cosmo
124 lines
5.1 KiB
C++
124 lines
5.1 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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// $Id: G4CrossSectionElasticScreenedRutherfordLE.cc,v 1.5 2009/06/11 15:47:08 mantero Exp $
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// GEANT4 tag $Name: geant4-09-03 $
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#include "G4CrossSectionElasticScreenedRutherfordLE.hh"
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4CrossSectionElasticScreenedRutherfordLE::G4CrossSectionElasticScreenedRutherfordLE()
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{
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lowEnergyLimit = 0 * eV;
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highEnergyLimit = 200 * eV;
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G4cout << G4endl;
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G4cout << "*******************************************************************************" << G4endl;
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G4cout << "*******************************************************************************" << G4endl;
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G4cout << " The class G4CrossSectionElasticScreenedRutherfordLE is NOT SUPPORTED ANYMORE. " << G4endl;
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G4cout << " It will be REMOVED with the next major release of Geant4. " << G4endl;
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G4cout << " Please consult: https://twiki.cern.ch/twiki/bin/view/Geant4/LoweProcesses" << G4endl;
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G4cout << "*******************************************************************************" << G4endl;
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G4cout << "*******************************************************************************" << G4endl;
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G4cout << G4endl;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4CrossSectionElasticScreenedRutherfordLE::~G4CrossSectionElasticScreenedRutherfordLE()
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{}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4CrossSectionElasticScreenedRutherfordLE::CrossSection(const G4Track& track)
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{
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const G4DynamicParticle* particle = track.GetDynamicParticle();
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G4double k = particle->GetKineticEnergy();
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G4double screenedCrossSection = 0.;
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if (k > lowEnergyLimit && k <= highEnergyLimit)
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{
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G4double z = 10.;
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G4double n = ScreeningFactor(k,z);
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G4double crossSection = RutherfordCrossSection(k, z);
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screenedCrossSection = pi * crossSection / (n * (n + 1.));
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}
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return screenedCrossSection;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4CrossSectionElasticScreenedRutherfordLE::RutherfordCrossSection(G4double k, G4double z)
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{
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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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// NIM 155, pp. 145-156, 1978
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G4double length =(e_squared * (k + electron_mass_c2)) / (4 * pi *epsilon0 * k * ( k + 2 * electron_mass_c2));
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G4double cross = z * ( z + 1) * length * length;
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return cross;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4CrossSectionElasticScreenedRutherfordLE::ScreeningFactor(G4double k, G4double z)
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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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// NIM 155, pp. 145-156, 1978
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// Formulae (2) and (5)
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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 = (alpha_1 + beta_1 * std::log(k/eV)) * constK * std::pow(z, 2./3.);
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k /= electron_mass_c2;
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G4double denominator = k * (2 + k);
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G4double value = 0.;
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if (denominator > 0.) value = numerator / denominator;
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return value;
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}
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