Gabriele Cosmo
279 lines
9.4 KiB
C++
279 lines
9.4 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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//
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// GEANT4 Class header file
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//
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//
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// File name: G4mplIonisationModel
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//
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// Author: Vladimir Ivanchenko
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//
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// Creation date: 06.09.2005
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//
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// Modifications:
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// 12.08.2007 Changing low energy approximation and extrapolation.
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// Small bug fixing and refactoring (M. Vladymyrov)
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// 13.11.2007 Use low-energy asymptotic from [3] (V.Ivanchenko)
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//
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//
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// -------------------------------------------------------------------
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// References
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// [1] Steven P. Ahlen: Energy loss of relativistic heavy ionizing particles,
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// S.P. Ahlen, Rev. Mod. Phys 52(1980), p121
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// [2] K.A. Milton arXiv:hep-ex/0602040
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// [3] S.P. Ahlen and K. Kinoshita, Phys. Rev. D26 (1982) 2347
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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#include "G4mplIonisationModel.hh"
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#include "Randomize.hh"
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#include "G4PhysicalConstants.hh"
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#include "G4SystemOfUnits.hh"
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#include "G4ParticleChangeForLoss.hh"
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#include "G4ProductionCutsTable.hh"
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#include "G4MaterialCutsCouple.hh"
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#include "G4Log.hh"
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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using namespace std;
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std::vector<G4double>* G4mplIonisationModel::dedx0 = nullptr;
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G4mplIonisationModel::G4mplIonisationModel(G4double mCharge, const G4String& nam)
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: G4VEmModel(nam),G4VEmFluctuationModel(nam),
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magCharge(mCharge),
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twoln10(log(100.0)),
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betalow(0.01),
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betalim(0.1),
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beta2lim(betalim*betalim),
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bg2lim(beta2lim*(1.0 + beta2lim))
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{
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nmpl = G4int(abs(magCharge) * 2 * fine_structure_const + 0.5);
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if(nmpl > 6) { nmpl = 6; }
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else if(nmpl < 1) { nmpl = 1; }
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pi_hbarc2_over_mc2 = pi * hbarc * hbarc / electron_mass_c2;
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chargeSquare = magCharge * magCharge;
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dedxlim = 45.*nmpl*nmpl*GeV*cm2/g;
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fParticleChange = nullptr;
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monopole = nullptr;
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mass = 0.0;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4mplIonisationModel::~G4mplIonisationModel()
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{
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if(IsMaster()) { delete dedx0; }
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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void G4mplIonisationModel::SetParticle(const G4ParticleDefinition* p)
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{
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monopole = p;
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mass = monopole->GetPDGMass();
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G4double emin =
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std::min(LowEnergyLimit(),0.1*mass*(1./sqrt(1. - betalow*betalow) - 1.));
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G4double emax =
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std::max(HighEnergyLimit(),10.*mass*(1./sqrt(1. - beta2lim) - 1.));
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SetLowEnergyLimit(emin);
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SetHighEnergyLimit(emax);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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void G4mplIonisationModel::Initialise(const G4ParticleDefinition* p,
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const G4DataVector&)
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{
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if(!monopole) { SetParticle(p); }
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if(!fParticleChange) { fParticleChange = GetParticleChangeForLoss(); }
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if(IsMaster()) {
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if(!dedx0) { dedx0 = new std::vector<G4double>; }
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G4ProductionCutsTable* theCoupleTable=
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G4ProductionCutsTable::GetProductionCutsTable();
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G4int numOfCouples = theCoupleTable->GetTableSize();
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G4int n = dedx0->size();
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if(n < numOfCouples) { dedx0->resize(numOfCouples); }
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// initialise vector
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for(G4int i=0; i<numOfCouples; ++i) {
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const G4Material* material =
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theCoupleTable->GetMaterialCutsCouple(i)->GetMaterial();
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G4double eDensity = material->GetElectronDensity();
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G4double vF = electron_Compton_length*pow(3.*pi*pi*eDensity,0.3333333333);
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(*dedx0)[i] = pi_hbarc2_over_mc2*eDensity*nmpl*nmpl*
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(G4Log(2.*vF/fine_structure_const) - 0.5)/vF;
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}
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}
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4mplIonisationModel::ComputeDEDXPerVolume(const G4Material* material,
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const G4ParticleDefinition* p,
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G4double kineticEnergy,
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G4double)
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{
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if(!monopole) { SetParticle(p); }
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G4double tau = kineticEnergy / mass;
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G4double gam = tau + 1.0;
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G4double bg2 = tau * (tau + 2.0);
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G4double beta2 = bg2 / (gam * gam);
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G4double beta = sqrt(beta2);
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// low-energy asymptotic formula
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//G4double dedx = dedxlim*beta*material->GetDensity();
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G4double dedx = (*dedx0)[CurrentCouple()->GetIndex()]*beta;
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// above asymptotic
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if(beta > betalow) {
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// high energy
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if(beta >= betalim) {
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dedx = ComputeDEDXAhlen(material, bg2);
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} else {
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//G4double dedx1 = dedxlim*betalow*material->GetDensity();
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G4double dedx1 = (*dedx0)[CurrentCouple()->GetIndex()]*betalow;
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G4double dedx2 = ComputeDEDXAhlen(material, bg2lim);
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// extrapolation between two formula
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G4double kapa2 = beta - betalow;
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G4double kapa1 = betalim - beta;
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dedx = (kapa1*dedx1 + kapa2*dedx2)/(kapa1 + kapa2);
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}
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}
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return dedx;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4mplIonisationModel::ComputeDEDXAhlen(const G4Material* material,
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G4double bg2)
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{
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G4double eDensity = material->GetElectronDensity();
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G4double eexc = material->GetIonisation()->GetMeanExcitationEnergy();
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G4double cden = material->GetIonisation()->GetCdensity();
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G4double mden = material->GetIonisation()->GetMdensity();
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G4double aden = material->GetIonisation()->GetAdensity();
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G4double x0den = material->GetIonisation()->GetX0density();
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G4double x1den = material->GetIonisation()->GetX1density();
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// Ahlen's formula for nonconductors, [1]p157, f(5.7)
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G4double dedx = log(2.0 * electron_mass_c2 * bg2 / eexc) - 0.5;
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// Kazama et al. cross-section correction
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G4double k = 0.406;
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if(nmpl > 1) k = 0.346;
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// Bloch correction
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const G4double B[7] = { 0.0, 0.248, 0.672, 1.022, 1.243, 1.464, 1.685};
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dedx += 0.5 * k - B[nmpl];
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// density effect correction
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G4double deltam;
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G4double x = log(bg2) / twoln10;
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if ( x >= x0den ) {
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deltam = twoln10 * x - cden;
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if ( x < x1den ) deltam += aden * pow((x1den-x), mden);
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dedx -= 0.5 * deltam;
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}
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// now compute the total ionization loss
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dedx *= pi_hbarc2_over_mc2 * eDensity * nmpl * nmpl;
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if (dedx < 0.0) dedx = 0.;
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return dedx;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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void G4mplIonisationModel::SampleSecondaries(std::vector<G4DynamicParticle*>*,
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const G4MaterialCutsCouple*,
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const G4DynamicParticle*,
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G4double,
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G4double)
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{}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4mplIonisationModel::SampleFluctuations(
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const G4MaterialCutsCouple* couple,
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const G4DynamicParticle* dp,
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G4double tmax,
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G4double length,
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G4double meanLoss)
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{
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G4double siga = Dispersion(couple->GetMaterial(),dp,tmax,length);
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G4double loss = meanLoss;
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siga = sqrt(siga);
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G4double twomeanLoss = meanLoss + meanLoss;
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if(twomeanLoss < siga) {
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G4double x;
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do {
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loss = twomeanLoss*G4UniformRand();
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x = (loss - meanLoss)/siga;
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// Loop checking, 07-Aug-2015, Vladimir Ivanchenko
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} while (1.0 - 0.5*x*x < G4UniformRand());
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} else {
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do {
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loss = G4RandGauss::shoot(meanLoss,siga);
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// Loop checking, 07-Aug-2015, Vladimir Ivanchenko
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} while (0.0 > loss || loss > twomeanLoss);
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}
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return loss;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4mplIonisationModel::Dispersion(const G4Material* material,
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const G4DynamicParticle* dp,
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G4double tmax,
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G4double length)
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{
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G4double siga = 0.0;
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G4double tau = dp->GetKineticEnergy()/mass;
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if(tau > 0.0) {
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G4double electronDensity = material->GetElectronDensity();
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G4double gam = tau + 1.0;
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G4double invbeta2 = (gam*gam)/(tau * (tau+2.0));
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siga = (invbeta2 - 0.5) * twopi_mc2_rcl2 * tmax * length
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* electronDensity * chargeSquare;
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}
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return siga;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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