Gabriele Cosmo
212 lines
7.6 KiB
C++
212 lines
7.6 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 file
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//
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//
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// File name: G4EmElementSelector
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//
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// Author: Vladimir Ivanchenko
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//
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// Creation date: 29.05.2008
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//
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// Modifications:
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//
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// Class Description:
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//
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// Generic helper class for the random selection of an element
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// -------------------------------------------------------------------
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//
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#include "G4EmElementSelector.hh"
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#include "G4VEmModel.hh"
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#include "G4SystemOfUnits.hh"
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4EmElementSelector::G4EmElementSelector(G4VEmModel* mod,
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const G4Material* mat,
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G4int bins,
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G4double emin,
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G4double emax,
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G4bool):
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model(mod), material(mat), nbins(bins), cutEnergy(-1.0),
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lowEnergy(emin), highEnergy(emax)
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{
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G4int n = material->GetNumberOfElements();
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nElmMinusOne = n - 1;
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theElementVector = material->GetElementVector();
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if(nElmMinusOne > 0) {
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xSections.reserve(n);
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auto v0 = new G4PhysicsLogVector(lowEnergy,highEnergy,nbins,false);
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xSections.push_back(v0);
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for(G4int i=1; i<n; ++i) {
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auto v = new G4PhysicsLogVector(*v0);
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xSections.push_back(v);
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}
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}
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/*
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G4cout << "G4EmElementSelector for " << mat->GetName() << " n= " << n
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<< " nbins= " << nbins << " Emin= " << lowEnergy
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<< " Emax= " << highEnergy << G4endl;
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*/
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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G4EmElementSelector::~G4EmElementSelector()
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{
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if(nElmMinusOne > 0) {
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for(G4int i=0; i<=nElmMinusOne; ++i) { delete xSections[i]; }
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}
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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void G4EmElementSelector::Initialise(const G4ParticleDefinition* part,
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G4double cut)
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{
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//G4cout << "G4EmElementSelector initialise for " << material->GetName()
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// << G4endl;
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if(0 == nElmMinusOne || cut == cutEnergy) { return; }
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cutEnergy = cut;
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//G4cout << "cut(keV)= " << cut/keV << G4endl;
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G4double cross;
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const G4double* theAtomNumDensityVector =
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material->GetVecNbOfAtomsPerVolume();
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// loop over bins
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for(G4int j=0; j<=nbins; ++j) {
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G4double e = (xSections[0])->Energy(j);
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model->SetupForMaterial(part, material, e);
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cross = 0.0;
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//G4cout << "j= " << j << " e(MeV)= " << e/MeV << G4endl;
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for (G4int i=0; i<=nElmMinusOne; ++i) {
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cross += theAtomNumDensityVector[i]*
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model->ComputeCrossSectionPerAtom(part, (*theElementVector)[i], e,
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cutEnergy, e);
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xSections[i]->PutValue(j, cross);
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}
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}
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// xSections start from null, so use probabilities from the next bin
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if(0.0 == (*xSections[nElmMinusOne])[0]) {
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for (G4int i=0; i<=nElmMinusOne; ++i) {
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xSections[i]->PutValue(0, (*xSections[i])[1]);
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}
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}
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// xSections ends with null, so use probabilities from the previous bin
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if(0.0 == (*xSections[nElmMinusOne])[nbins]) {
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for (G4int i=0; i<=nElmMinusOne; ++i) {
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xSections[i]->PutValue(nbins, (*xSections[i])[nbins-1]);
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}
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}
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// perform normalization
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for(G4int j=0; j<=nbins; ++j) {
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cross = (*xSections[nElmMinusOne])[j];
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// only for positive X-section
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if(cross > 0.0) {
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for (G4int i=0; i<nElmMinusOne; ++i) {
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G4double x = (*xSections[i])[j]/cross;
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xSections[i]->PutValue(j, x);
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}
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}
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}
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/*
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G4cout << "======== G4EmElementSelector for the " << model->GetName()
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<< G4endl;
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for (G4int i=0; i<=nElmMinusOne; ++i) {
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G4cout << "#### i=" << i << G4endl;
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G4cout << (*xSections[i]) << G4endl;
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}
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*/
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
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const G4Element*
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G4EmElementSelector::SelectRandomAtom(const G4double e,
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const G4double loge) const
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{
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const G4Element* element = (*theElementVector)[nElmMinusOne];
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if (nElmMinusOne > 0) {
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// 1. Determine energy index (only once)
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// handle cases below/above the enrgy grid (by ekin, idx that gives a=0/1)
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// ekin = x[0] if e<=x[0] and idx will be 0 ^ a=0 => so y=y0
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// ekin = x[N-1] if e>=x[N-1] and idx will be N-2 ^ a=1 => so y=y_{N-1}
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G4double ekin = e;
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std::size_t idx = 0;
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if(e <= (xSections[0])->Energy(0)) {
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ekin = (xSections[0])->Energy(0);
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} else if(e < (xSections[0])->GetMaxEnergy()) {
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idx = (xSections[0])->ComputeLogVectorBin(loge);
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} else {
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ekin = (xSections[0])->GetMaxEnergy();
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idx = (xSections[0])->GetVectorLength() - 2;
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}
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// 2. Do the linear interp.(corner cases are already excluded)
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const G4double x1 = (xSections[0])->Energy(idx);
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const G4double a = (ekin - x1)/((xSections[0])->Energy(idx+1) - x1);
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const G4double urnd = G4UniformRand();
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for (G4int i = 0; i < nElmMinusOne; ++i) {
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const G4double y1 = (*xSections[i])[idx];
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if (urnd <= y1 + a*((*xSections[i])[idx+1] - y1)) {
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element = (*theElementVector)[i];
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break;
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}
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}
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}
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return element;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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void G4EmElementSelector::Dump(const G4ParticleDefinition* part)
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{
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G4cout << "======== G4EmElementSelector for the " << model->GetName();
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if(part) G4cout << " and " << part->GetParticleName();
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G4cout << " for " << material->GetName() << " ========" << G4endl;
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if(0 < nElmMinusOne) {
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for(G4int i=0; i<nElmMinusOne; i++) {
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G4cout << " " << (*theElementVector)[i]->GetName() << " : " << G4endl;
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G4cout << *(xSections[i]) << G4endl;
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}
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}
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G4cout << "Last Element in element vector "
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<< (*theElementVector)[nElmMinusOne]->GetName()
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<< G4endl;
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G4cout << G4endl;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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