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dab42d20185975fb0910dadfc6aa9998d9d9e06d
geant4/source/processes/electromagnetic/standard/src/G4WentzelOKandVIxSection.cc
T
Gabriele Cosmo dab42d2018 Import Geant4 10.7.0 source tree
2020-12-04 12:30:43 +01:00

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//
// ********************************************************************
// * License and Disclaimer *
// * *
// * The Geant4 software is copyright of the Copyright Holders of *
// * the Geant4 Collaboration. It is provided under the terms and *
// * conditions of the Geant4 Software License, included in the file *
// * LICENSE and available at http://cern.ch/geant4/license . These *
// * include a list of copyright holders. *
// * *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work make any representation or warranty, express or implied, *
// * regarding this software system or assume any liability for its *
// * use. Please see the license in the file LICENSE and URL above *
// * for the full disclaimer and the limitation of liability. *
// * *
// * This code implementation is the result of the scientific and *
// * technical work of the GEANT4 collaboration. *
// * By using, copying, modifying or distributing the software (or *
// * any work based on the software) you agree to acknowledge its *
// * use in resulting scientific publications, and indicate your *
// * acceptance of all terms of the Geant4 Software license. *
// ********************************************************************
//
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name: G4WentzelOKandVIxSection
//
// Author: V.Ivanchenko
//
// Creation date: 09.04.2008 from G4MuMscModel
//
// Modifications:
//
// -------------------------------------------------------------------
//
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
#include "G4WentzelOKandVIxSection.hh"
#include "G4ScreeningMottCrossSection.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "Randomize.hh"
#include "G4Electron.hh"
#include "G4Positron.hh"
#include "G4Proton.hh"
#include "G4EmParameters.hh"
#include "G4Log.hh"
#include "G4Exp.hh"
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
G4double G4WentzelOKandVIxSection::ScreenRSquareElec[] = {0.0};
G4double G4WentzelOKandVIxSection::ScreenRSquare[] = {0.0};
G4double G4WentzelOKandVIxSection::FormFactor[] = {0.0};
#ifdef G4MULTITHREADED
G4Mutex G4WentzelOKandVIxSection::WentzelOKandVIxSectionMutex = G4MUTEX_INITIALIZER;
#endif
using namespace std;
G4WentzelOKandVIxSection::G4WentzelOKandVIxSection(G4bool comb) :
temp(0.,0.,0.),
numlimit(0.1),
nwarnings(0),
nwarnlimit(50),
isCombined(comb),
cosThetaMax(-1.0),
alpha2(fine_structure_const*fine_structure_const)
{
fNistManager = G4NistManager::Instance();
fG4pow = G4Pow::GetInstance();
fMottXSection = nullptr;
theElectron = G4Electron::Electron();
thePositron = G4Positron::Positron();
theProton = G4Proton::Proton();
lowEnergyLimit = 1.0*eV;
G4double p0 = electron_mass_c2*classic_electr_radius;
coeff = twopi*p0*p0;
particle = nullptr;
fNucFormfactor = fExponentialNF;
currentMaterial = nullptr;
factB = factD = formfactA = screenZ = 0.0;
cosTetMaxElec = cosTetMaxNuc = invbeta2 = kinFactor = fMottFactor
= gam0pcmp = pcmp2 = 1.0;
factB1= 0.5*CLHEP::pi*fine_structure_const;
tkin = mom2 = momCM2 = factorA2 = mass = spin = chargeSquare = charge3 = 0.0;
ecut = etag = DBL_MAX;
targetZ = 0;
targetMass = CLHEP::proton_mass_c2;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
G4WentzelOKandVIxSection::~G4WentzelOKandVIxSection()
{
delete fMottXSection;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void G4WentzelOKandVIxSection::Initialise(const G4ParticleDefinition* p,
G4double cosThetaLim)
{
SetupParticle(p);
tkin = mom2 = momCM2 = 0.0;
ecut = etag = DBL_MAX;
targetZ = 0;
// cosThetaMax is below 1.0 only when MSC is combined with SS
if(isCombined) { cosThetaMax = cosThetaLim; }
G4EmParameters* param = G4EmParameters::Instance();
G4double a = param->FactorForAngleLimit()*CLHEP::hbarc/CLHEP::fermi;
factorA2 = 0.5*a*a;
currentMaterial = nullptr;
fNucFormfactor = param->NuclearFormfactorType();
if(0.0 == ScreenRSquare[0]) { InitialiseA(); }
// Mott corrections always added
if((p == theElectron || p == thePositron) && !fMottXSection) {
fMottXSection = new G4ScreeningMottCrossSection();
fMottXSection->Initialise(p, 1.0);
}
/*
G4cout << "G4WentzelOKandVIxSection::Initialise for "
<< p->GetParticleName() << " cosThetaMax= " << cosThetaMax
<< " " << ScreenRSquare[0] << " coeff= " << coeff << G4endl;
*/
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void G4WentzelOKandVIxSection::InitialiseA()
{
// Thomas-Fermi screening radii
// Formfactors from A.V. Butkevich et al., NIM A 488 (2002) 282
#ifdef G4MULTITHREADED
G4MUTEXLOCK(&G4WentzelOKandVIxSection::WentzelOKandVIxSectionMutex);
if(0.0 == ScreenRSquare[0]) {
#endif
G4double a0 = electron_mass_c2/0.88534;
G4double constn = 6.937e-6/(MeV*MeV);
G4double fct = G4EmParameters::Instance()->ScreeningFactor();
G4double afact = 0.5*fct*alpha2*a0*a0;
ScreenRSquare[0] = afact;
ScreenRSquare[1] = afact;
ScreenRSquareElec[1] = afact;
FormFactor[1] = 3.097e-6/(MeV*MeV);
for(G4int j=2; j<100; ++j) {
G4double x = fG4pow->Z13(j);
ScreenRSquare[j] = afact*(1 + G4Exp(-j*j*0.001))*x*x;
ScreenRSquareElec[j] = afact*x*x;
x = fNistManager->GetA27(j);
FormFactor[j] = constn*x*x;
}
#ifdef G4MULTITHREADED
}
G4MUTEXUNLOCK(&G4WentzelOKandVIxSection::WentzelOKandVIxSectionMutex);
#endif
//G4cout << "G4WentzelOKandVIxSection::Initialise mass= " << mass
// << " " << p->GetParticleName()
// << " cosThetaMax= " << cosThetaMax << G4endl;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void G4WentzelOKandVIxSection::SetupParticle(const G4ParticleDefinition* p)
{
particle = p;
mass = particle->GetPDGMass();
spin = particle->GetPDGSpin();
if(0.0 != spin) { spin = 0.5; }
G4double q = std::abs(particle->GetPDGCharge()/eplus);
chargeSquare = q*q;
charge3 = chargeSquare*q;
tkin = 0.0;
currentMaterial = nullptr;
targetZ = 0;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double
G4WentzelOKandVIxSection::SetupKinematic(G4double ekin, const G4Material* mat)
{
if(ekin != tkin || mat != currentMaterial) {
currentMaterial = mat;
tkin = ekin;
mom2 = tkin*(tkin + 2.0*mass);
invbeta2 = 1.0 + mass*mass/mom2;
factB = spin/invbeta2;
cosTetMaxNuc = isCombined ?
std::max(cosThetaMax, 1.-factorA2*mat->GetIonisation()->GetInvA23()/mom2)
: cosThetaMax;
}
return cosTetMaxNuc;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4double
G4WentzelOKandVIxSection::SetupTarget(G4int Z, G4double cut)
{
G4double cosTetMaxNuc2 = cosTetMaxNuc;
if(Z != targetZ || tkin != etag) {
etag = tkin;
targetZ = std::min(Z, 99);
G4double massT = (1 == Z) ? CLHEP::proton_mass_c2 :
fNistManager->GetAtomicMassAmu(Z)*CLHEP::amu_c2;
SetTargetMass(massT);
kinFactor = coeff*Z*chargeSquare*invbeta2/mom2;
if(particle == theElectron && fMottXSection) {
fMottFactor = (1.0 + 2.0e-4*Z*Z);
}
if(1 == Z) {
screenZ = ScreenRSquare[targetZ]/mom2;
} else if(mass > MeV) {
screenZ = std::min(Z*1.13,1.13 +3.76*Z*Z*invbeta2*alpha2*chargeSquare)*
ScreenRSquare[targetZ]/mom2;
} else {
G4double tau = tkin/mass;
screenZ = std::min(Z*1.13,(1.13 +3.76*Z*Z
*invbeta2*alpha2*std::sqrt(tau/(tau + fG4pow->Z23(targetZ)))))*
ScreenRSquareElec[targetZ]/mom2;
}
if(targetZ == 1 && particle == theProton && cosTetMaxNuc2 < 0.0) {
cosTetMaxNuc2 = 0.0;
}
formfactA = FormFactor[targetZ]*mom2;
cosTetMaxElec = 1.0;
ComputeMaxElectronScattering(cut);
}
//G4cout << "SetupTarget: Z= " << targetZ << " kinFactor= " << kinFactor
// << " fMottFactor= " << fMottFactor << " screenZ= " << screenZ <<G4endl;
return cosTetMaxNuc2;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
G4double
G4WentzelOKandVIxSection::ComputeTransportCrossSectionPerAtom(G4double cosTMax)
{
G4double xSection = 0.0;
if(cosTMax >= 1.0) { return xSection; }
G4double costm = std::max(cosTMax,cosTetMaxElec);
G4double fb = screenZ*factB;
// scattering off electrons
if(costm < 1.0) {
G4double x = (1.0 - costm)/screenZ;
if(x < numlimit) {
G4double x2 = 0.5*x*x;
xSection = x2*((1.0 - 1.3333333*x + 3*x2) - fb*x*(0.6666667 - x));
} else {
G4double x1= x/(1 + x);
G4double xlog = G4Log(1.0 + x);
xSection = xlog - x1 - fb*(x + x1 - 2*xlog);
}
if(xSection < 0.0) {
++nwarnings;
if(nwarnings < nwarnlimit) {
G4cout << "G4WentzelOKandVIxSection::ComputeTransportCrossSectionPerAtom"
<< " scattering on e- <0"
<< G4endl;
G4cout << "cross= " << xSection
<< " e(MeV)= " << tkin << " p(MeV/c)= " << sqrt(mom2)
<< " Z= " << targetZ << " "
<< particle->GetParticleName() << G4endl;
G4cout << " 1-costm= " << 1.0-costm << " screenZ= " << screenZ
<< " x= " << x << G4endl;
}
xSection = 0.0;
}
}
/*
G4cout << "G4WentzelOKandVIxSection::ComputeTransportCrossSectionPerAtom: \n"
<< " Z= " << targetZ
<< " e(MeV)= " << tkin/MeV << " XSel= " << xSection
<< " zmaxE= " << (1.0 - cosTetMaxElec)/screenZ
<< " zmaxN= " << (1.0 - cosThetaMax)/screenZ
<< " 1-costm= " << 1.0 - cosThetaMax << G4endl;
*/
// scattering off nucleus
if(cosTMax < 1.0) {
G4double x = (1.0 - cosTMax)/screenZ;
G4double y;
if(x < numlimit) {
G4double x2 = 0.5*x*x;
y = x2*((1.0 - 1.3333333*x + 3*x2) - fb*x*(0.6666667 - x));
} else {
G4double x1= x/(1 + x);
G4double xlog = G4Log(1.0 + x);
y = xlog - x1 - fb*(x + x1 - 2*xlog);
}
if(y < 0.0) {
++nwarnings;
if(nwarnings < nwarnlimit) {
G4cout << "G4WentzelOKandVIxSection::ComputeTransportCrossSectionPerAtom"
<< " scattering on nucleus <0"
<< G4endl;
G4cout << "y= " << y
<< " e(MeV)= " << tkin << " Z= " << targetZ << " "
<< particle->GetParticleName() << G4endl;
G4cout << " formfactA= " << formfactA << " screenZ= " << screenZ
<< " x= " << x <<G4endl;
}
y = 0.0;
}
xSection += y*targetZ;
}
xSection *= kinFactor;
/*
G4cout << "Z= " << targetZ << " XStot= " << xSection/barn
<< " screenZ= " << screenZ << " formF= " << formfactA
<< " for " << particle->GetParticleName()
<< " m= " << mass << " 1/v= " << sqrt(invbeta2)
<< " p= " << sqrt(mom2)
<< " x= " << x << G4endl;
*/
return xSection;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4ThreeVector&
G4WentzelOKandVIxSection::SampleSingleScattering(G4double cosTMin,
G4double cosTMax,
G4double elecRatio)
{
temp.set(0.0,0.0,1.0);
CLHEP::HepRandomEngine* rndmEngineMod = G4Random::getTheEngine();
G4double formf = formfactA;
G4double cost1 = cosTMin;
G4double cost2 = cosTMax;
if(elecRatio > 0.0) {
if(rndmEngineMod->flat() <= elecRatio) {
formf = 0.0;
cost1 = std::max(cost1,cosTetMaxElec);
cost2 = std::max(cost2,cosTetMaxElec);
}
}
if(cost1 > cost2) {
G4double w1 = 1. - cost1 + screenZ;
G4double w2 = 1. - cost2 + screenZ;
G4double z1 = w1*w2/(w1 + rndmEngineMod->flat()*(w2 - w1)) - screenZ;
G4double fm = 1.0;
if(fNucFormfactor == fExponentialNF) {
fm += formf*z1;
fm = 1.0/(fm*fm);
} else if(fNucFormfactor == fGaussianNF) {
fm = G4Exp(-2*formf*z1);
} else if(fNucFormfactor == fFlatNF) {
static const G4double ccoef = 0.00508/MeV;
G4double x = std::sqrt(2.*mom2*z1)*ccoef*2.;
fm = FlatFormfactor(x);
fm *= FlatFormfactor(x*0.6
*fG4pow->A13(fNistManager->GetAtomicMassAmu(targetZ)));
}
G4double grej;
if(fMottXSection) {
fMottXSection->SetupKinematic(tkin, targetZ);
grej = fMottXSection->RatioMottRutherfordCosT(std::sqrt(z1))*fm*fm;
} else {
grej = (1. - z1*factB + factB1*targetZ*sqrt(z1*factB)*(2. - z1))
*fm*fm/(1.0 + z1*factD);
}
// G4cout << "SampleSingleScattering: E= " << tkin << " z1= "
// << z1 << " grej= "<< grej << " mottFact= "<< fMottFactor<< G4endl;
if(fMottFactor*rndmEngineMod->flat() <= grej ) {
// exclude "false" scattering due to formfactor and spin effect
G4double cost = 1.0 - z1;
if(cost > 1.0) { cost = 1.0; }
else if(cost < -1.0) { cost =-1.0; }
G4double sint = sqrt((1.0 - cost)*(1.0 + cost));
//G4cout << "sint= " << sint << G4endl;
G4double phi = twopi*rndmEngineMod->flat();
temp.set(sint*cos(phi),sint*sin(phi),cost);
}
}
return temp;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
void
G4WentzelOKandVIxSection::ComputeMaxElectronScattering(G4double cutEnergy)
{
if(mass > MeV) {
G4double ratio = electron_mass_c2/mass;
G4double tau = tkin/mass;
G4double tmax = 2.0*electron_mass_c2*tau*(tau + 2.)/
(1.0 + 2.0*ratio*(tau + 1.0) + ratio*ratio);
cosTetMaxElec = 1.0 - std::min(cutEnergy, tmax)*electron_mass_c2/mom2;
} else {
G4double tmax = (particle == theElectron) ? 0.5*tkin : tkin;
G4double t = std::min(cutEnergy, tmax);
G4double mom21 = t*(t + 2.0*electron_mass_c2);
G4double t1 = tkin - t;
//G4cout <<"tkin=" <<tkin<<" tmax= "<<tmax<<" t= "
//<<t<< " t1= "<<t1<<" cut= "<<ecut<<G4endl;
if(t1 > 0.0) {
G4double mom22 = t1*(t1 + 2.0*mass);
G4double ctm = (mom2 + mom22 - mom21)*0.5/sqrt(mom2*mom22);
if(ctm < 1.0) { cosTetMaxElec = ctm; }
if(particle == theElectron && cosTetMaxElec < 0.0) {
cosTetMaxElec = 0.0;
}
}
}
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
G4double
G4WentzelOKandVIxSection::ComputeSecondTransportMoment(G4double /*CosThetaMax*/)
{
return 0.0;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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