Gabriele Cosmo
236 lines
7.1 KiB
C++
236 lines
7.1 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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//
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//
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// Author: Vladimir Grichine
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//
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// History:
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//
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// 14.10.12 V.Grichine, update of xsc and angular distribution
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// 25.05.2011 first implementation
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#include "G4XrayRayleighModel.hh"
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#include "G4PhysicalConstants.hh"
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#include "G4SystemOfUnits.hh"
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//////////////////////////////////////////////////////////////////////////////////
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const G4double G4XrayRayleighModel::fCofA = 2.*pi2*Bohr_radius*Bohr_radius;
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const G4double G4XrayRayleighModel::fCofR = 8.*pi*classic_electr_radius*classic_electr_radius/3.;
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//////////////////////////////////////////////////////////////////////////////////
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G4XrayRayleighModel::G4XrayRayleighModel(const G4ParticleDefinition*,
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const G4String& nam)
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:G4VEmModel(nam),isInitialised(false)
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{
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fParticleChange = nullptr;
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lowEnergyLimit = 250*eV;
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highEnergyLimit = 10.*MeV;
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fFormFactor = 0.0;
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// SetLowEnergyLimit(lowEnergyLimit);
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SetHighEnergyLimit(highEnergyLimit);
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//
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verboseLevel= 0;
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// Verbosity scale:
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// 0 = nothing
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// 1 = warning for energy non-conservation
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// 2 = details of energy budget
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// 3 = calculation of cross sections, file openings, sampling of atoms
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// 4 = entering in methods
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if(verboseLevel > 0)
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{
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G4cout << "Xray Rayleigh is constructed " << G4endl
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<< "Energy range: "
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<< lowEnergyLimit / eV << " eV - "
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<< highEnergyLimit / MeV << " MeV"
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<< G4endl;
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}
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}
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//////////////////////////////////////////////////////////////////////////////////
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G4XrayRayleighModel::~G4XrayRayleighModel() = default;
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//////////////////////////////////////////////////////////////////////////////////
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void G4XrayRayleighModel::Initialise(const G4ParticleDefinition* particle,
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const G4DataVector& cuts)
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{
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if (verboseLevel > 3)
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{
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G4cout << "Calling G4XrayRayleighModel::Initialise()" << G4endl;
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}
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InitialiseElementSelectors(particle,cuts);
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if(isInitialised) return;
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fParticleChange = GetParticleChangeForGamma();
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isInitialised = true;
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}
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//////////////////////////////////////////////////////////////////////////////////
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G4double G4XrayRayleighModel::ComputeCrossSectionPerAtom(
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const G4ParticleDefinition*,
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G4double gammaEnergy,
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G4double Z, G4double,
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G4double, G4double)
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{
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if (verboseLevel > 3)
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{
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G4cout << "Calling CrossSectionPerAtom() of G4XrayRayleighModel" << G4endl;
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}
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if (gammaEnergy < lowEnergyLimit || gammaEnergy > highEnergyLimit)
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{
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return 0.0;
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}
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G4double k = gammaEnergy/hbarc;
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k *= Bohr_radius;
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G4double p0 = 0.680654;
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G4double p1 = -0.0224188;
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G4double lnZ = std::log(Z);
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G4double lna = p0 + p1*lnZ;
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G4double alpha = std::exp(lna);
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G4double fo = std::pow(k, alpha);
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p0 = 3.68455;
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p1 = -0.464806;
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lna = p0 + p1*lnZ;
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fo *= 0.01*std::exp(lna);
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fFormFactor = fo;
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G4double b = 1. + 2.*fo;
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G4double b2 = b*b;
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G4double b3 = b*b2;
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G4double xsc = fCofR*Z*Z/b3;
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xsc *= fo*fo + (1. + fo)*(1. + fo);
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return xsc;
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}
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//////////////////////////////////////////////////////////////////////////////////
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void G4XrayRayleighModel::SampleSecondaries(std::vector<G4DynamicParticle*>* /*fvect*/,
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const G4MaterialCutsCouple* couple,
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const G4DynamicParticle* aDPGamma,
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G4double,
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G4double)
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{
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if ( verboseLevel > 3)
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{
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G4cout << "Calling SampleSecondaries() of G4XrayRayleighModel" << G4endl;
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}
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G4double photonEnergy0 = aDPGamma->GetKineticEnergy();
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G4ParticleMomentum photonDirection0 = aDPGamma->GetMomentumDirection();
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// Sample the angle of the scattered photon
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// according to 1 + cosTheta*cosTheta distribution
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G4double cosDipole, cosTheta, sinTheta;
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G4double c, delta, cofA, signc = 1., a, power = 1./3.;
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c = 4. - 8.*G4UniformRand();
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a = c;
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if( c < 0. )
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{
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signc = -1.;
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a = -c;
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}
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delta = std::sqrt(a*a+4.);
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delta += a;
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delta *= 0.5;
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cofA = -signc*std::pow(delta, power);
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cosDipole = cofA - 1./cofA;
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// select atom
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const G4Element* elm = SelectTargetAtom(couple, aDPGamma->GetParticleDefinition(),
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photonEnergy0,aDPGamma->GetLogKineticEnergy());
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G4double Z = elm->GetZ();
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G4double k = photonEnergy0/hbarc;
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k *= Bohr_radius;
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G4double p0 = 0.680654;
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G4double p1 = -0.0224188;
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G4double lnZ = std::log(Z);
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G4double lna = p0 + p1*lnZ;
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G4double alpha = std::exp(lna);
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G4double fo = std::pow(k, alpha);
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p0 = 3.68455;
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p1 = -0.464806;
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lna = p0 + p1*lnZ;
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fo *= 0.01*pi*std::exp(lna);
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G4double beta = fo/(1 + fo);
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cosTheta = (cosDipole + beta)/(1. + cosDipole*beta);
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if( cosTheta > 1.) cosTheta = 1.;
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if( cosTheta < -1.) cosTheta = -1.;
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sinTheta = std::sqrt( (1. - cosTheta)*(1. + cosTheta) );
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// Scattered photon angles. ( Z - axis along the parent photon)
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G4double phi = twopi * G4UniformRand() ;
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G4double dirX = sinTheta*std::cos(phi);
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G4double dirY = sinTheta*std::sin(phi);
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G4double dirZ = cosTheta;
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// Update G4VParticleChange for the scattered photon
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G4ThreeVector photonDirection1(dirX, dirY, dirZ);
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photonDirection1.rotateUz(photonDirection0);
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fParticleChange->ProposeMomentumDirection(photonDirection1);
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fParticleChange->SetProposedKineticEnergy(photonEnergy0);
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}
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