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This commit is contained in:
Gabriele Cosmo
2016-06-10 12:08:39 +02:00
parent 286caacf06
commit c9b32a6c0a
5770 changed files with 1050949 additions and 367105 deletions
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source/processes/electromagnetic/highenergy/src/G4GammaConversionToMuons.cc
+89 -76
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@@ -24,7 +24,7 @@
// ********************************************************************
//
//
// $Id: G4GammaConversionToMuons.cc 66872 2013-01-15 01:25:57Z japost $
// $Id: G4GammaConversionToMuons.cc 83660 2014-09-08 09:57:12Z gcosmo $
//
// ------------ G4GammaConversionToMuons physics process ------
// by H.Burkhardt, S. Kelner and R. Kokoulin, April 2002
@@ -40,18 +40,28 @@
#include "G4UnitsTable.hh"
#include "G4MuonPlus.hh"
#include "G4MuonMinus.hh"
#include "G4EmProcessSubType.hh"
#include "G4NistManager.hh"
#include "G4Log.hh"
#include "G4Exp.hh"
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
using namespace std;
static const G4double sqrte=sqrt(exp(1.));
static const G4double PowSat=-0.88;
G4GammaConversionToMuons::G4GammaConversionToMuons(const G4String& processName,
G4ProcessType type):G4VDiscreteProcess (processName, type),
LowestEnergyLimit (4*G4MuonPlus::MuonPlus()->GetPDGMass()), // 4*Mmuon
G4ProcessType type)
: G4VDiscreteProcess (processName, type),
Mmuon(G4MuonPlus::MuonPlus()->GetPDGMass()),
Rc(elm_coupling/Mmuon),
LowestEnergyLimit (4*Mmuon), // 4*Mmuon
HighestEnergyLimit(1e21*eV), // ok to 1e21eV=1e12GeV, then LPM suppression
CrossSecFactor(1.)
{
SetProcessSubType(15);
SetProcessSubType(fGammaConversionToMuMu);
MeanFreePath = DBL_MAX;
}
@@ -59,8 +69,8 @@ G4GammaConversionToMuons::G4GammaConversionToMuons(const G4String& processName,
// destructor
G4GammaConversionToMuons::~G4GammaConversionToMuons() // (empty) destructor
{ }
G4GammaConversionToMuons::~G4GammaConversionToMuons()
{}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
@@ -91,7 +101,7 @@ G4double G4GammaConversionToMuons::GetMeanFreePath(const G4Track& aTrack,
G4double GammaEnergy = aDynamicGamma->GetKineticEnergy();
G4Material* aMaterial = aTrack.GetMaterial();
if (GammaEnergy < LowestEnergyLimit)
if (GammaEnergy <= LowestEnergyLimit)
MeanFreePath = DBL_MAX;
else
MeanFreePath = ComputeMeanFreePath(GammaEnergy,aMaterial);
@@ -111,7 +121,7 @@ G4double G4GammaConversionToMuons::ComputeMeanFreePath(G4double GammaEnergy,
G4double SIGMA = 0 ;
for ( size_t i=0 ; i < aMaterial->GetNumberOfElements() ; i++ )
for ( size_t i=0 ; i < aMaterial->GetNumberOfElements(); ++i)
{
G4double AtomicZ = (*theElementVector)[i]->GetZ();
G4double AtomicA = (*theElementVector)[i]->GetA()/(g/mole);
@@ -131,7 +141,7 @@ G4double G4GammaConversionToMuons::GetCrossSectionPerAtom(
{
G4double GammaEnergy = aDynamicGamma->GetKineticEnergy();
G4double AtomicZ = anElement->GetZ();
G4double AtomicA = anElement->GetA()/(g/mole);
G4double AtomicA = anElement->GetN();
G4double crossSection =
ComputeCrossSectionPerAtom(GammaEnergy,AtomicZ,AtomicA);
return crossSection;
@@ -140,50 +150,43 @@ G4double G4GammaConversionToMuons::GetCrossSectionPerAtom(
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
G4double G4GammaConversionToMuons::ComputeCrossSectionPerAtom(
G4double Egam, G4double Z, G4double A)
G4double Egam, G4double ZZ, G4double)
// Calculates the microscopic cross section in GEANT4 internal units.
// Total cross section parametrisation from H.Burkhardt
// It gives a good description at any energy (from 0 to 10**21 eV)
{ static const G4double Mmuon=G4MuonPlus::MuonPlus()->GetPDGMass();
static const G4double Mele=electron_mass_c2;
static const G4double Rc=elm_coupling/Mmuon; // classical particle radius
static const G4double sqrte=sqrt(exp(1.));
static const G4double PowSat=-0.88;
{
if(Egam <= LowestEnergyLimit) return 0 ; // below threshold return 0
static G4ThreadLocal G4double CrossSection = 0.0 ;
G4int Z = G4lrint(ZZ);
G4double CrossSection = 0.0;
G4NistManager* nist = G4NistManager::Instance();
if ( A < 1. ) return 0;
if ( Egam < 4*Mmuon ) return 0 ; // below threshold return 0
static G4ThreadLocal G4double EgamLast=0,Zlast=0,PowThres,Ecor,B,Dn,Zthird,Winfty,WMedAppr,
Wsatur,sigfac;
G4double PowThres,Ecor,B,Dn,Zthird,Winfty,WMedAppr,
Wsatur,sigfac;
if(Zlast==Z && Egam==EgamLast) return CrossSection; // already calculated
EgamLast=Egam;
if(Zlast!=Z) // new element
{ Zlast=Z;
if(Z==1) // special case of Hydrogen
if(Z==1) // special case of Hydrogen
{ B=202.4;
Dn=1.49;
}
else
else
{ B=183.;
Dn=1.54*pow(A,0.27);
Dn=1.54*nist->GetA27(Z);
}
Zthird=pow(Z,-1./3.); // Z**(-1/3)
Winfty=B*Zthird*Mmuon/(Dn*Mele);
WMedAppr=1./(4.*Dn*sqrte*Mmuon);
Wsatur=Winfty/WMedAppr;
sigfac=4.*fine_structure_const*Z*Z*Rc*Rc;
PowThres=1.479+0.00799*Dn;
Ecor=-18.+4347./(B*Zthird);
}
G4double CorFuc=1.+.04*log(1.+Ecor/Egam);
G4double Eg=pow(1.-4.*Mmuon/Egam,PowThres)*pow( pow(Wsatur,PowSat)+
pow(Egam,PowSat),1./PowSat); // threshold and saturation
CrossSection=7./9.*sigfac*log(1.+WMedAppr*CorFuc*Eg);
Zthird=1./nist->GetZ13(Z); // Z**(-1/3)
Winfty=B*Zthird*Mmuon/(Dn*electron_mass_c2);
WMedAppr=1./(4.*Dn*sqrte*Mmuon);
Wsatur=Winfty/WMedAppr;
sigfac=4.*fine_structure_const*Z*Z*Rc*Rc;
PowThres=1.479+0.00799*Dn;
Ecor=-18.+4347./(B*Zthird);
G4double CorFuc=1.+.04*G4Log(1.+Ecor/Egam);
//G4double Eg=pow(1.-4.*Mmuon/Egam,PowThres)*pow( pow(Wsatur,PowSat)+
// pow(Egam,PowSat),1./PowSat); // threshold and saturation
G4double Eg=G4Exp(G4Log(1.-4.*Mmuon/Egam)*PowThres)*
G4Exp(G4Log( G4Exp(G4Log(Wsatur)*PowSat)+G4Exp(G4Log(Egam)*PowSat))/PowSat);
CrossSection=7./9.*sigfac*G4Log(1.+WMedAppr*CorFuc*Eg);
CrossSection*=CrossSecFactor; // increase the CrossSection by (by default 1)
return CrossSection;
}
@@ -192,7 +195,8 @@ G4double G4GammaConversionToMuons::ComputeCrossSectionPerAtom(
void G4GammaConversionToMuons::SetCrossSecFactor(G4double fac)
// Set the factor to artificially increase the cross section
{ CrossSecFactor=fac;
{
CrossSecFactor=fac;
G4cout << "The cross section for GammaConversionToMuons is artificially "
<< "increased by the CrossSecFactor=" << CrossSecFactor << G4endl;
}
@@ -209,39 +213,35 @@ G4VParticleChange* G4GammaConversionToMuons::PostStepDoIt(
aParticleChange.Initialize(aTrack);
G4Material* aMaterial = aTrack.GetMaterial();
static const G4double Mmuon=G4MuonPlus::MuonPlus()->GetPDGMass();
static const G4double Mele=electron_mass_c2;
static const G4double sqrte=sqrt(exp(1.));
// current Gamma energy and direction, return if energy too low
const G4DynamicParticle *aDynamicGamma = aTrack.GetDynamicParticle();
G4double Egam = aDynamicGamma->GetKineticEnergy();
if (Egam < 4*Mmuon) return G4VDiscreteProcess::PostStepDoIt(aTrack,aStep);
if (Egam <= LowestEnergyLimit) {
return G4VDiscreteProcess::PostStepDoIt(aTrack,aStep);
}
G4ParticleMomentum GammaDirection = aDynamicGamma->GetMomentumDirection();
// select randomly one element constituting the material
const G4Element& anElement = *SelectRandomAtom(aDynamicGamma, aMaterial);
G4double Z = anElement.GetZ();
G4double A = anElement.GetA()/(g/mole);
const G4Element* anElement = SelectRandomAtom(aDynamicGamma, aMaterial);
G4int Z = G4lrint(anElement->GetZ());
G4NistManager* nist = G4NistManager::Instance();
static G4ThreadLocal G4double Zlast=0,B,Dn,Zthird,Winfty,A027,C1Num2,C2Term2;
if(Zlast!=Z) // the element has changed
{ Zlast=Z;
if(Z==1) // special case of Hydrogen
G4double B,Dn;
G4double A027 = nist->GetA27(Z);
if(Z==1) // special case of Hydrogen
{ B=202.4;
Dn=1.49;
}
else
else
{ B=183.;
Dn=1.54*pow(A,0.27);
Dn=1.54*A027;
}
Zthird=pow(Z,-1./3.); // Z**(-1/3)
Winfty=B*Zthird*Mmuon/(Dn*Mele);
A027=pow(A,0.27);
G4double C1Num=0.35*A027;
C1Num2=C1Num*C1Num;
C2Term2=Mele/(183.*Zthird*Mmuon);
}
G4double Zthird=1./nist->GetZ13(Z); // Z**(-1/3)
G4double Winfty=B*Zthird*Mmuon/(Dn*electron_mass_c2);
G4double C1Num=0.35*A027;
G4double C1Num2=C1Num*C1Num;
G4double C2Term2=electron_mass_c2/(183.*Zthird*Mmuon);
G4double GammaMuonInv=Mmuon/Egam;
G4double sqrtx=sqrt(.25-GammaMuonInv);
@@ -250,23 +250,26 @@ G4VParticleChange* G4GammaConversionToMuons::PostStepDoIt(
// generate xPlus according to the differential cross section by rejection
G4double Ds2=(Dn*sqrte-2.);
G4double sBZ=sqrte*B*Zthird/Mele;
G4double LogWmaxInv=1./log(Winfty*(1.+2.*Ds2*GammaMuonInv)
/(1.+2.*sBZ*Mmuon*GammaMuonInv));
G4double sBZ=sqrte*B*Zthird/electron_mass_c2;
G4double LogWmaxInv=1./G4Log(Winfty*(1.+2.*Ds2*GammaMuonInv)
/(1.+2.*sBZ*Mmuon*GammaMuonInv));
G4double xPlus,xMinus,xPM,result,W;
G4int nn = 0;
const G4int nmax = 1000;
do
{ xPlus=xmin+G4UniformRand()*(xmax-xmin);
xMinus=1.-xPlus;
xPM=xPlus*xMinus;
G4double del=Mmuon*Mmuon/(2.*Egam*xPM);
W=Winfty*(1.+Ds2*del/Mmuon)/(1.+sBZ*del);
if(W<1.) W=1.; // to avoid negative cross section at xmin
if(W<=1. || nn > nmax) { break; } // to avoid negative cross section at xmin
G4double xxp=1.-4./3.*xPM; // the main xPlus dependence
result=xxp*log(W)*LogWmaxInv;
result=xxp*G4Log(W)*LogWmaxInv;
if(result>1.) {
G4cout << "G4GammaConversionToMuons::PostStepDoIt WARNING:"
<< " in dSigxPlusGen, result=" << result << " > 1" << G4endl;
}
++nn;
}
while (G4UniformRand() > result);
@@ -276,7 +279,7 @@ G4VParticleChange* G4GammaConversionToMuons::PostStepDoIt(
G4double rho;
G4double thetaPlus,thetaMinus,phiHalf; // final angular variables
nn = 0;
do // t, psi, rho generation start (while angle < pi)
{
//generate t by the rejection method
@@ -284,7 +287,9 @@ G4VParticleChange* G4GammaConversionToMuons::PostStepDoIt(
G4double f1_max=(1.-xPM) / (1.+C1);
G4double f1; // the probability density
do
{ t=G4UniformRand();
{
++nn;
t=G4UniformRand();
f1=(1.-2.*xPM+4.*xPM*t*(1.-t)) / (1.+C1/(t*t));
if(f1<0 || f1> f1_max) // should never happend
{
@@ -301,7 +306,9 @@ G4VParticleChange* G4GammaConversionToMuons::PostStepDoIt(
// long version
G4double f2;
do
{ psi=2.*pi*G4UniformRand();
{
++nn;
psi=2.*pi*G4UniformRand();
f2=1.-2.*xPM+4.*xPM*t*(1.-t)*(1.+cos(2.*psi));
if(f2<0 || f2> f2_max) // should never happend
{
@@ -317,8 +324,8 @@ G4VParticleChange* G4GammaConversionToMuons::PostStepDoIt(
G4double C2Term1=GammaMuonInv/(2.*xPM*t);
G4double C2=4./sqrt(xPM)*pow(C2Term1*C2Term1+C2Term2*C2Term2,2.);
G4double rhomax=1.9/A027*(1./t-1.);
G4double beta=log( (C2+pow(rhomax,4.))/C2 );
rho=pow(C2 *( exp(beta*G4UniformRand())-1. ) ,0.25);
G4double beta=G4Log( (C2+rhomax*rhomax*rhomax*rhomax)/C2 );
rho=G4Exp(G4Log(C2 *( G4Exp(beta*G4UniformRand())-1. ))*0.25);
//now get from t and psi the kinematical variables
G4double u=sqrt(1./t-1.);
@@ -328,6 +335,12 @@ G4VParticleChange* G4GammaConversionToMuons::PostStepDoIt(
thetaPlus =GammaMuonInv*(u+xiHalf)/xPlus;
thetaMinus=GammaMuonInv*(u-xiHalf)/xMinus;
// protection against infinite loop
if(nn > nmax) {
if(std::abs(thetaPlus)>pi) { thetaPlus = 0.0; }
if(std::abs(thetaMinus)>pi) { thetaMinus = 0.0; }
}
} while ( std::abs(thetaPlus)>pi || std::abs(thetaMinus) >pi);
// now construct the vectors
@@ -366,8 +379,8 @@ G4VParticleChange* G4GammaConversionToMuons::PostStepDoIt(
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.....
G4Element* G4GammaConversionToMuons::SelectRandomAtom(
const G4DynamicParticle* aDynamicGamma,
G4Material* aMaterial)
const G4DynamicParticle* aDynamicGamma,
G4Material* aMaterial)
{
// select randomly 1 element within the material, invoked by PostStepDoIt
@@ -381,7 +394,7 @@ G4Element* G4GammaConversionToMuons::SelectRandomAtom(
G4double rval = G4UniformRand()/MeanFreePath;
for ( G4int i=0 ; i < NumberOfElements ; i++ )
for ( G4int i=0 ; i < NumberOfElements ; ++i)
{ PartialSumSigma += NbOfAtomsPerVolume[i] *
GetCrossSectionPerAtom(aDynamicGamma, (*theElementVector)[i]);
if (rval <= PartialSumSigma) return ((*theElementVector)[i]);