Gabriele Cosmo
484 lines
15 KiB
C++
484 lines
15 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: G4MuBremsstrahlungModel.cc,v 1.35 2009/04/12 17:48:45 vnivanch Exp $
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// GEANT4 tag $Name: geant4-09-03 $
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//
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// -------------------------------------------------------------------
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//
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// GEANT4 Class file
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//
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//
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// File name: G4MuBremsstrahlungModel
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//
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// Author: Vladimir Ivanchenko on base of Laszlo Urban code
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//
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// Creation date: 24.06.2002
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//
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// Modifications:
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//
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// 04-12-02 Change G4DynamicParticle constructor in PostStepDoIt (V.Ivanchenko)
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// 23-12-02 Change interface in order to move to cut per region (V.Ivanchenko)
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// 24-01-03 Fix for compounds (V.Ivanchenko)
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// 27-01-03 Make models region aware (V.Ivanchenko)
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// 13-02-03 Add name (V.Ivanchenko)
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// 10-02-04 Add lowestKinEnergy (V.Ivanchenko)
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// 08-04-05 Major optimisation of internal interfaces (V.Ivanchenko)
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// 03-08-05 Angular correlations according to PRM (V.Ivanchenko)
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// 13-02-06 add ComputeCrossSectionPerAtom (mma)
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// 21-03-06 Fix problem of initialisation in case when cuts are not defined (VI)
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// 07-11-07 Improve sampling of final state (A.Bogdanov)
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// 28-02-08 Use precomputed Z^1/3 and Log(A) (V.Ivanchenko)
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//
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//
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// Class Description:
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//
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//
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// -------------------------------------------------------------------
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//
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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#include "G4MuBremsstrahlungModel.hh"
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#include "G4Gamma.hh"
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#include "G4MuonMinus.hh"
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#include "G4MuonPlus.hh"
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#include "Randomize.hh"
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#include "G4Material.hh"
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#include "G4Element.hh"
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#include "G4ElementVector.hh"
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#include "G4ProductionCutsTable.hh"
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#include "G4ParticleChangeForLoss.hh"
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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using namespace std;
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G4MuBremsstrahlungModel::G4MuBremsstrahlungModel(const G4ParticleDefinition* p,
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const G4String& nam)
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: G4VEmModel(nam),
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particle(0),
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sqrte(sqrt(exp(1.))),
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bh(202.4),
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bh1(446.),
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btf(183.),
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btf1(1429.),
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fParticleChange(0),
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lowestKinEnergy(1.0*GeV),
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minThreshold(1.0*keV)
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{
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theGamma = G4Gamma::Gamma();
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nist = G4NistManager::Instance();
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if(p) SetParticle(p);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4MuBremsstrahlungModel::~G4MuBremsstrahlungModel()
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{
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size_t n = partialSumSigma.size();
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if(n > 0) {
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for(size_t i=0; i<n; i++) {
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delete partialSumSigma[i];
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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 G4MuBremsstrahlungModel::MinEnergyCut(const G4ParticleDefinition*,
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const G4MaterialCutsCouple*)
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{
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return minThreshold;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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void G4MuBremsstrahlungModel::Initialise(const G4ParticleDefinition* p,
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const G4DataVector& cuts)
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{
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if(p) SetParticle(p);
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highKinEnergy = HighEnergyLimit();
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// partial cross section is computed for fixed energy
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G4double fixedEnergy = 0.5*highKinEnergy;
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const G4ProductionCutsTable* theCoupleTable=
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G4ProductionCutsTable::GetProductionCutsTable();
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if(theCoupleTable) {
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G4int numOfCouples = theCoupleTable->GetTableSize();
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// clear old data
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G4int nn = partialSumSigma.size();
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G4int nc = cuts.size();
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if(nn > 0) {
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for (G4int ii=0; ii<nn; ii++){
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G4DataVector* a = partialSumSigma[ii];
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if ( a ) delete a;
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}
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partialSumSigma.clear();
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}
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// fill new data
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if (numOfCouples>0) {
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for (G4int i=0; i<numOfCouples; i++) {
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G4double cute = DBL_MAX;
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// protection for usage with extrapolator
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if(i < nc) cute = cuts[i];
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const G4MaterialCutsCouple* couple =
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theCoupleTable->GetMaterialCutsCouple(i);
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const G4Material* material = couple->GetMaterial();
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G4DataVector* dv = ComputePartialSumSigma(material,fixedEnergy,cute);
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partialSumSigma.push_back(dv);
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}
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}
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}
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// define pointer to G4ParticleChange
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if(!fParticleChange) fParticleChange = GetParticleChangeForLoss();
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4MuBremsstrahlungModel::ComputeDEDXPerVolume(
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const G4Material* material,
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const G4ParticleDefinition*,
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G4double kineticEnergy,
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G4double cutEnergy)
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{
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G4double dedx = 0.0;
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if (kineticEnergy <= lowestKinEnergy) return dedx;
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G4double tmax = kineticEnergy;
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G4double cut = std::min(cutEnergy,tmax);
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if(cut < minThreshold) cut = minThreshold;
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const G4ElementVector* theElementVector = material->GetElementVector();
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const G4double* theAtomicNumDensityVector =
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material->GetAtomicNumDensityVector();
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// loop for elements in the material
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for (size_t i=0; i<material->GetNumberOfElements(); i++) {
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G4double loss =
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ComputMuBremLoss((*theElementVector)[i]->GetZ(), kineticEnergy, cut);
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dedx += loss*theAtomicNumDensityVector[i];
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}
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// G4cout << "BR e= " << kineticEnergy << " dedx= " << dedx << G4endl;
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if(dedx < 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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G4double G4MuBremsstrahlungModel::ComputMuBremLoss(G4double Z,
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G4double tkin, G4double cut)
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{
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G4double totalEnergy = mass + tkin;
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G4double ak1 = 0.05;
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G4int k2=5;
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G4double xgi[]={0.03377,0.16940,0.38069,0.61931,0.83060,0.96623};
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G4double wgi[]={0.08566,0.18038,0.23396,0.23396,0.18038,0.08566};
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G4double loss = 0.;
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G4double vcut = cut/totalEnergy;
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G4double vmax = tkin/totalEnergy;
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G4double aaa = 0.;
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G4double bbb = vcut;
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if(vcut>vmax) bbb=vmax ;
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G4int kkk = (G4int)((bbb-aaa)/ak1)+k2 ;
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G4double hhh=(bbb-aaa)/float(kkk) ;
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G4double aa = aaa;
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for(G4int l=0; l<kkk; l++)
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{
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for(G4int i=0; i<6; i++)
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{
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G4double ep = (aa + xgi[i]*hhh)*totalEnergy;
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loss += ep*wgi[i]*ComputeDMicroscopicCrossSection(tkin, Z, ep);
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}
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aa += hhh;
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}
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loss *=hhh*totalEnergy ;
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return loss;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4MuBremsstrahlungModel::ComputeMicroscopicCrossSection(
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G4double tkin,
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G4double Z,
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G4double cut)
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{
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G4double totalEnergy = tkin + mass;
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G4double ak1 = 2.3;
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G4int k2 = 4;
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G4double xgi[]={0.03377,0.16940,0.38069,0.61931,0.83060,0.96623};
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G4double wgi[]={0.08566,0.18038,0.23396,0.23396,0.18038,0.08566};
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G4double cross = 0.;
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if(cut >= tkin) return cross;
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G4double vcut = cut/totalEnergy;
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G4double vmax = tkin/totalEnergy;
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G4double aaa = log(vcut);
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G4double bbb = log(vmax);
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G4int kkk = (G4int)((bbb-aaa)/ak1)+k2 ;
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G4double hhh = (bbb-aaa)/G4double(kkk);
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G4double aa = aaa;
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for(G4int l=0; l<kkk; l++)
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{
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for(G4int i=0; i<6; i++)
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{
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G4double ep = exp(aa + xgi[i]*hhh)*totalEnergy;
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cross += ep*wgi[i]*ComputeDMicroscopicCrossSection(tkin, Z, ep);
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}
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aa += hhh;
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}
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cross *=hhh;
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//G4cout << "BR e= " << tkin<< " cross= " << cross/barn << G4endl;
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return cross;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4MuBremsstrahlungModel::ComputeDMicroscopicCrossSection(
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G4double tkin,
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G4double Z,
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G4double gammaEnergy)
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// differential cross section
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{
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G4double dxsection = 0.;
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if( gammaEnergy > tkin) return dxsection ;
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G4double E = tkin + mass ;
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G4double v = gammaEnergy/E ;
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G4double delta = 0.5*mass*mass*v/(E-gammaEnergy) ;
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G4double rab0=delta*sqrte ;
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G4int iz = G4int(Z);
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if(iz < 1) iz = 1;
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G4double z13 = 1.0/nist->GetZ13(iz);
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G4double dn = 1.54*nist->GetA27(iz);
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G4double b,b1,dnstar ;
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if(1 == iz)
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{
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b = bh;
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b1 = bh1;
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dnstar = dn;
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}
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else
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{
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b = btf;
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b1 = btf1;
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dnstar = dn/std::pow(dn, 1./Z);
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}
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// nucleus contribution logarithm
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G4double rab1=b*z13;
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G4double fn=log(rab1/(dnstar*(electron_mass_c2+rab0*rab1))*
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(mass+delta*(dnstar*sqrte-2.))) ;
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if(fn <0.) fn = 0. ;
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// electron contribution logarithm
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G4double epmax1=E/(1.+0.5*mass*rmass/E) ;
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G4double fe=0.;
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if(gammaEnergy<epmax1)
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{
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G4double rab2=b1*z13*z13 ;
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fe=log(rab2*mass/((1.+delta*rmass/(electron_mass_c2*sqrte))*
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(electron_mass_c2+rab0*rab2))) ;
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if(fe<0.) fe=0. ;
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}
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dxsection = coeff*(1.-v*(1. - 0.75*v))*Z*(fn*Z + fe)/gammaEnergy;
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return dxsection;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4double G4MuBremsstrahlungModel::ComputeCrossSectionPerAtom(
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const G4ParticleDefinition*,
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G4double kineticEnergy,
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G4double Z, G4double,
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G4double cutEnergy,
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G4double maxEnergy)
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{
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G4double cross = 0.0;
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if (kineticEnergy <= lowestKinEnergy) return cross;
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G4double tmax = std::min(maxEnergy, kineticEnergy);
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G4double cut = std::min(cutEnergy, kineticEnergy);
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if(cut < minThreshold) cut = minThreshold;
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if (cut >= tmax) return cross;
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cross = ComputeMicroscopicCrossSection (kineticEnergy, Z, cut);
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if(tmax < kineticEnergy) {
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cross -= ComputeMicroscopicCrossSection(kineticEnergy, Z, tmax);
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}
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return cross;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4DataVector* G4MuBremsstrahlungModel::ComputePartialSumSigma(
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const G4Material* material,
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G4double kineticEnergy,
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G4double cut)
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// Build the table of cross section per element.
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// The table is built for material
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// This table is used to select randomly an element in the material.
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{
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G4int nElements = material->GetNumberOfElements();
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const G4ElementVector* theElementVector = material->GetElementVector();
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const G4double* theAtomNumDensityVector =
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material->GetAtomicNumDensityVector();
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G4DataVector* dv = new G4DataVector();
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G4double cross = 0.0;
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for (G4int i=0; i<nElements; i++ ) {
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cross += theAtomNumDensityVector[i]
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* ComputeMicroscopicCrossSection(kineticEnergy,
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(*theElementVector)[i]->GetZ(), cut);
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dv->push_back(cross);
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}
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return dv;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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void G4MuBremsstrahlungModel::SampleSecondaries(
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std::vector<G4DynamicParticle*>* vdp,
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const G4MaterialCutsCouple* couple,
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const G4DynamicParticle* dp,
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G4double minEnergy,
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G4double maxEnergy)
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{
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G4double kineticEnergy = dp->GetKineticEnergy();
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// check against insufficient energy
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G4double tmax = std::min(kineticEnergy, maxEnergy);
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G4double tmin = std::min(kineticEnergy, minEnergy);
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if(tmin < minThreshold) tmin = minThreshold;
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if(tmin >= tmax) return;
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// ===== sampling of energy transfer ======
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G4ParticleMomentum partDirection = dp->GetMomentumDirection();
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// select randomly one element constituing the material
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const G4Element* anElement = SelectRandomAtom(couple);
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G4double Z = anElement->GetZ();
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G4double totalEnergy = kineticEnergy + mass;
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G4double totalMomentum = sqrt(kineticEnergy*(kineticEnergy + 2.0*mass));
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G4double func1 = tmin*
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ComputeDMicroscopicCrossSection(kineticEnergy,Z,tmin);
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G4double lnepksi, epksi;
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G4double func2;
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do {
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lnepksi = log(tmin) + G4UniformRand()*log(kineticEnergy/tmin);
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epksi = exp(lnepksi);
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func2 = epksi*ComputeDMicroscopicCrossSection(kineticEnergy,Z,epksi);
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} while(func2 < func1*G4UniformRand());
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G4double gEnergy = epksi;
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// ===== sample angle =====
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G4double gam = totalEnergy/mass;
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G4double rmax = gam*std::min(1.0, totalEnergy/gEnergy - 1.0);
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G4double rmax2= rmax*rmax;
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G4double x = G4UniformRand()*rmax2/(1.0 + rmax2);
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G4double theta = sqrt(x/(1.0 - x))/gam;
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G4double sint = sin(theta);
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G4double phi = twopi * G4UniformRand() ;
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G4double dirx = sint*cos(phi), diry = sint*sin(phi), dirz = cos(theta) ;
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G4ThreeVector gDirection(dirx, diry, dirz);
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gDirection.rotateUz(partDirection);
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partDirection *= totalMomentum;
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partDirection -= gEnergy*gDirection;
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partDirection = partDirection.unit();
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// primary change
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kineticEnergy -= gEnergy;
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fParticleChange->SetProposedKineticEnergy(kineticEnergy);
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fParticleChange->SetProposedMomentumDirection(partDirection);
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// save secondary
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G4DynamicParticle* aGamma =
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new G4DynamicParticle(theGamma,gDirection,gEnergy);
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vdp->push_back(aGamma);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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const G4Element* G4MuBremsstrahlungModel::SelectRandomAtom(
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const G4MaterialCutsCouple* couple) const
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{
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// select randomly 1 element within the material
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const G4Material* material = couple->GetMaterial();
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G4int nElements = material->GetNumberOfElements();
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const G4ElementVector* theElementVector = material->GetElementVector();
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if(1 == nElements) return (*theElementVector)[0];
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else if(1 > nElements) return 0;
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G4DataVector* dv = partialSumSigma[couple->GetIndex()];
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G4double rval = G4UniformRand()*((*dv)[nElements-1]);
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for (G4int i=0; i<nElements; i++) {
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if (rval <= (*dv)[i]) return (*theElementVector)[i];
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}
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return (*theElementVector)[nElements-1];
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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