Gabriele Cosmo
159 lines
6.4 KiB
Plaintext
159 lines
6.4 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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// ===========================================================================
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// GEANT4 class
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//
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// Class: G4IonParametrisedLossModel
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//
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// Base class: G4VEmModel (utils)
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//
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// Author: Anton Lechner (Anton.Lechner@cern.ch)
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//
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// First implementation: 10. 11. 2008
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//
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// Modifications: 03. 02. 2009 - Bug fix iterators (AL)
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// 11. 03. 2009 - Introduced new table handler (G4IonDEDXHandler)
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// and modified method to add/remove tables
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// (tables are now built in initialisation phase),
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// Minor bug fix in ComputeDEDXPerVolume (AL)
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// 20. 11. 2009 - Added set-method for energy loss limit (AL)
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// 04. 11. 2010 - Moved virtual methods to the source (VI)
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//
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// Class description:
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// Model for computing the energy loss of ions by employing a
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// parameterisation of dE/dx tables (default ICRU 73 tables). For
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// ion-material combinations and/or projectile energies not covered
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// by this model, the G4BraggIonModel and G4BetheBloch models are
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// employed.
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//
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// Comments:
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//
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// ===========================================================================
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inline G4double G4IonParametrisedLossModel::DeltaRayMeanEnergyTransferRate(
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const G4Material* material,
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const G4ParticleDefinition* particle,
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G4double kineticEnergy,
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G4double cutEnergy) {
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// ############## Mean energy transferred to delta-rays ###################
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// Computes the mean energy transfered to delta-rays per unit length,
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// considering only delta-rays with energies above the energy threshold
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// (energy cut)
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//
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// The mean energy transfer rate is derived by using the differential
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// cross section given in the references below.
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//
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// See Geant4 physics reference manual (version 9.1), section 9.1.3
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//
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// Ref.: W.M. Yao et al, Jour. of Phys. G 33 (2006) 1.
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// B. Rossi, High energy particles, New York, NY: Prentice-Hall (1952).
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//
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// (Implementation adapted from G4BraggIonModel)
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// *** Variables:
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// kineticEnergy = kinetic energy of projectile
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// totEnergy = total energy of projectile, i.e. kinetic energy
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// plus rest energy (Mc^2)
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// betaSquared = beta of projectile squared, calculated as
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// beta^2 = 1 - 1 / (E/Mc^2)^2
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// = T * ( E + Mc^2 ) / E^2
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// where T = kineticEnergy, E = totEnergy
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// cutEnergy = energy threshold for secondary particle production
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// i.e. energy cut, below which energy transfered to
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// electrons is treated as continuous loss of projectile
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// maxKinEnergy = maximum energy transferable to secondary electrons
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// meanRate = mean kinetic energy of delta ray (per unit length)
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// (above cutEnergy)
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G4double meanRate = 0.0;
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G4double maxKinEnergy = MaxSecondaryEnergy(particle, kineticEnergy);
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if (cutEnergy < maxKinEnergy) {
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G4double totalEnergy = kineticEnergy + cacheMass;
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G4double betaSquared = kineticEnergy *
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(totalEnergy + cacheMass) / (totalEnergy * totalEnergy);
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G4double cutMaxEnergyRatio = cutEnergy / maxKinEnergy;
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meanRate =
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(- std::log(cutMaxEnergyRatio) - (1.0 - cutMaxEnergyRatio) * betaSquared) *
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CLHEP::twopi_mc2_rcl2 *
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(material->GetTotNbOfElectPerVolume()) / betaSquared;
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meanRate *= GetChargeSquareRatio(particle, material, kineticEnergy);
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}
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return meanRate;
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}
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inline
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void G4IonParametrisedLossModel::UpdateCache(
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const G4ParticleDefinition* particle) {
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cacheParticle = particle;
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cacheMass = particle -> GetPDGMass();
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cacheElecMassRatio = CLHEP::electron_mass_c2 / cacheMass;
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G4double q = particle -> GetPDGCharge() / CLHEP::eplus;
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cacheChargeSquare = q * q;
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}
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inline
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LossTableList::iterator G4IonParametrisedLossModel::IsApplicable(
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const G4ParticleDefinition* particle, // Projectile (ion)
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const G4Material* material) { // Target material
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LossTableList::iterator iter = lossTableList.end();
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LossTableList::iterator iterTables = lossTableList.begin();
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LossTableList::iterator iterTables_end = lossTableList.end();
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for(;iterTables != iterTables_end; iterTables++) {
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G4bool isApplicable = (*iterTables) ->
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IsApplicable(particle, material);
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if(isApplicable) {
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iter = iterTables;
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break;
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}
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}
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return iter;
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}
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inline
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void G4IonParametrisedLossModel::SetEnergyLossLimit(
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G4double ionEnergyLossLimit) {
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if(ionEnergyLossLimit > 0 && ionEnergyLossLimit <=1) {
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energyLossLimit = ionEnergyLossLimit;
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}
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}
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