G4HeatedKleinNishinaCompton Class Reference

#include <G4HeatedKleinNishinaCompton.hh>

Inheritance diagram for G4HeatedKleinNishinaCompton:

G4VEmModel

Public Member Functions

 G4HeatedKleinNishinaCompton (const G4ParticleDefinition *p=0, const G4String &nam="Heated-Klein-Nishina")
virtual ~G4HeatedKleinNishinaCompton ()
virtual void Initialise (const G4ParticleDefinition *, const G4DataVector &)
virtual G4double ComputeCrossSectionPerAtom (const G4ParticleDefinition *, G4double kinEnergy, G4double Z, G4double A, G4double cut, G4double emax)
virtual void SampleSecondaries (std::vector< G4DynamicParticle * > *, const G4MaterialCutsCouple *, const G4DynamicParticle *, G4double tmin, G4double maxEnergy)
void SetElectronTemperature (G4double t)
G4double GetElectronTemperature ()

Protected Attributes

G4ParticleDefinition * theGamma
G4ParticleDefinition * theElectron
G4ParticleChangeForGamma * fParticleChange
G4double lowestGammaEnergy
G4double fTemperature

Detailed Description

Definition at line 59 of file G4HeatedKleinNishinaCompton.hh.

Constructor & Destructor Documentation

G4HeatedKleinNishinaCompton::G4HeatedKleinNishinaCompton ( const G4ParticleDefinition *  p = 0,
const G4String &  nam = "Heated-Klein-Nishina" 
)

Definition at line 67 of file G4HeatedKleinNishinaCompton.cc.

References G4Electron::Electron(), fParticleChange, fTemperature, G4Gamma::Gamma(), lowestGammaEnergy, theElectron, and theGamma.

00069   : G4VEmModel(nam)
00070 {
00071   theGamma = G4Gamma::Gamma();
00072   theElectron = G4Electron::Electron();
00073   lowestGammaEnergy = 1.0*eV;
00074   fTemperature = 1.0*keV;
00075   fParticleChange = 0;
00076 }

G4HeatedKleinNishinaCompton::~G4HeatedKleinNishinaCompton (  )  [virtual]

Definition at line 80 of file G4HeatedKleinNishinaCompton.cc.

00081 {}

Member Function Documentation

G4double G4HeatedKleinNishinaCompton::ComputeCrossSectionPerAtom ( const G4ParticleDefinition *  ,
G4double  kinEnergy,
G4double  Z,
G4double  A,
G4double  cut,
G4double  emax 
) [virtual]

Reimplemented from G4VEmModel.

Definition at line 95 of file G4HeatedKleinNishinaCompton.cc.

00100 {
00101   G4double xSection = 0.0 ;
00102   if ( Z < 0.9999 )                 return xSection;
00103   if ( GammaEnergy < 0.01*keV      ) return xSection;
00104   //  if ( GammaEnergy > (100.*GeV/Z) ) return xSection;
00105 
00106   static const G4double a = 20.0 , b = 230.0 , c = 440.0;
00107   
00108   static const G4double
00109     d1= 2.7965e-1*barn, d2=-1.8300e-1*barn, d3= 6.7527   *barn, d4=-1.9798e+1*barn,
00110     e1= 1.9756e-5*barn, e2=-1.0205e-2*barn, e3=-7.3913e-2*barn, e4= 2.7079e-2*barn,
00111     f1=-3.9178e-7*barn, f2= 6.8241e-5*barn, f3= 6.0480e-5*barn, f4= 3.0274e-4*barn;
00112      
00113   G4double p1Z = Z*(d1 + e1*Z + f1*Z*Z), p2Z = Z*(d2 + e2*Z + f2*Z*Z),
00114            p3Z = Z*(d3 + e3*Z + f3*Z*Z), p4Z = Z*(d4 + e4*Z + f4*Z*Z);
00115 
00116   G4double T0  = 15.0*keV; 
00117   if (Z < 1.5) T0 = 40.0*keV; 
00118 
00119   G4double X   = max(GammaEnergy, T0) / electron_mass_c2;
00120   xSection = p1Z*std::log(1.+2.*X)/X
00121                + (p2Z + p3Z*X + p4Z*X*X)/(1. + a*X + b*X*X + c*X*X*X);
00122                 
00123   //  modification for low energy. (special case for Hydrogen)
00124   if (GammaEnergy < T0) {
00125     G4double dT0 = 1.*keV;
00126     X = (T0+dT0) / electron_mass_c2 ;
00127     G4double sigma = p1Z*log(1.+2*X)/X
00128                     + (p2Z + p3Z*X + p4Z*X*X)/(1. + a*X + b*X*X + c*X*X*X);
00129     G4double   c1 = -T0*(sigma-xSection)/(xSection*dT0);             
00130     G4double   c2 = 0.150; 
00131     if (Z > 1.5) c2 = 0.375-0.0556*log(Z);
00132     G4double    y = log(GammaEnergy/T0);
00133     xSection *= exp(-y*(c1+c2*y));          
00134   }
00135   //  G4cout << "e= " << GammaEnergy << " Z= " << Z << " cross= " << xSection << G4endl;
00136   return xSection;
00137 }

G4double G4HeatedKleinNishinaCompton::GetElectronTemperature (  )  [inline]

Definition at line 86 of file G4HeatedKleinNishinaCompton.hh.

00086 {return fTemperature;};

void G4HeatedKleinNishinaCompton::Initialise ( const G4ParticleDefinition *  ,
const G4DataVector &   
) [virtual]

Implements G4VEmModel.

Definition at line 85 of file G4HeatedKleinNishinaCompton.cc.

References fParticleChange, and G4VEmModel::GetParticleChangeForGamma().

00087 {
00088   if(!fParticleChange) fParticleChange = GetParticleChangeForGamma();
00089 }

void G4HeatedKleinNishinaCompton::SampleSecondaries ( std::vector< G4DynamicParticle * > *  ,
const G4MaterialCutsCouple *  ,
const G4DynamicParticle *  ,
G4double  tmin,
G4double  maxEnergy 
) [virtual]

Implements G4VEmModel.

Definition at line 143 of file G4HeatedKleinNishinaCompton.cc.

References DBL_MIN, fParticleChange, fStopAndKill, fTemperature, G4RandomDirection(), G4UniformRand, G4DynamicParticle::Get4Momentum(), G4VParticleChange::GetLocalEnergyDeposit(), lowestGammaEnergy, G4VParticleChange::ProposeLocalEnergyDeposit(), G4ParticleChangeForGamma::ProposeMomentumDirection(), G4VParticleChange::ProposeTrackStatus(), G4ParticleChangeForGamma::SetProposedKineticEnergy(), and theElectron.

00148 {
00149   // The scattered gamma energy is sampled according to Klein - Nishina formula.
00150   // The random number techniques of Butcher & Messel are used 
00151   // (Nuc Phys 20(1960),15).
00152   // Note : Effects due to binding of atomic electrons are negliged.
00153 
00154   // We start to prepare a heated electron from Maxwell distribution. 
00155   // Then we try to boost to the electron rest frame and make scattering.
00156   // The final step is to recover new gamma 4momentum in the lab frame
00157 
00158   G4double eMomentumC2   = CLHEP::RandGamma::shoot(1.5,1.);
00159   eMomentumC2          *= 2*electron_mass_c2*fTemperature; // electron (pc)^2
00160   G4ThreeVector eMomDir = G4RandomDirection();
00161   eMomDir              *= std::sqrt(eMomentumC2);
00162   G4double eEnergy      = std::sqrt(eMomentumC2+electron_mass_c2*electron_mass_c2);
00163   G4LorentzVector electron4v = G4LorentzVector(eMomDir,eEnergy);
00164   G4ThreeVector bst = electron4v.boostVector();
00165 
00166   G4LorentzVector gamma4v = aDynamicGamma->Get4Momentum();
00167   gamma4v.boost(-bst);
00168 
00169   G4ThreeVector gammaMomV = gamma4v.vect();
00170   G4double  gamEnergy0    = gammaMomV.mag();
00171  
00172  
00173   // G4double gamEnergy0 = aDynamicGamma->GetKineticEnergy();
00174   G4double E0_m = gamEnergy0 / electron_mass_c2 ;
00175 
00176   // G4ThreeVector gamDirection0 = /aDynamicGamma->GetMomentumDirection();
00177 
00178   G4ThreeVector gamDirection0 = gammaMomV/gamEnergy0;
00179   
00180   // sample the energy rate of the scattered gamma in the electron rest frame
00181   //
00182 
00183   G4double epsilon, epsilonsq, onecost, sint2, greject ;
00184 
00185   G4double eps0       = 1./(1. + 2.*E0_m);
00186   G4double epsilon0sq = eps0*eps0;
00187   G4double alpha1     = - log(eps0);
00188   G4double alpha2     = 0.5*(1.- epsilon0sq);
00189 
00190   do 
00191   {
00192     if ( alpha1/(alpha1+alpha2) > G4UniformRand() ) 
00193     {
00194       epsilon   = exp(-alpha1*G4UniformRand());   // eps0**r
00195       epsilonsq = epsilon*epsilon; 
00196 
00197     } 
00198     else 
00199     {
00200       epsilonsq = epsilon0sq + (1.- epsilon0sq)*G4UniformRand();
00201       epsilon   = sqrt(epsilonsq);
00202     };
00203 
00204     onecost = (1.- epsilon)/(epsilon*E0_m);
00205     sint2   = onecost*(2.-onecost);
00206     greject = 1. - epsilon*sint2/(1.+ epsilonsq);
00207 
00208   } while (greject < G4UniformRand());
00209  
00210   //
00211   // scattered gamma angles. ( Z - axis along the parent gamma)
00212   //
00213 
00214   G4double cosTeta = 1. - onecost; 
00215   G4double sinTeta = sqrt (sint2);
00216   G4double Phi     = twopi * G4UniformRand();
00217   G4double dirx    = sinTeta*cos(Phi), diry = sinTeta*sin(Phi), dirz = cosTeta;
00218 
00219   //
00220   // update G4VParticleChange for the scattered gamma
00221   //
00222    
00223   G4ThreeVector gamDirection1 ( dirx,diry,dirz );
00224   gamDirection1.rotateUz(gamDirection0);
00225   G4double gamEnergy1  = epsilon*gamEnergy0;
00226   gamDirection1       *= gamEnergy1;
00227 
00228   G4LorentzVector gamma4vfinal = G4LorentzVector(gamDirection1,gamEnergy1);
00229 
00230   
00231   // kinematic of the scattered electron
00232   //
00233 
00234   G4double eKinEnergy = gamEnergy0 - gamEnergy1;
00235   G4ThreeVector eDirection = gamEnergy0*gamDirection0 - gamEnergy1*gamDirection1;
00236   eDirection = eDirection.unit();
00237   G4double eFinalMom = std::sqrt(eKinEnergy*(eKinEnergy+2*electron_mass_c2));
00238   eDirection *= eFinalMom;
00239   G4LorentzVector e4vfinal = G4LorentzVector(eDirection,gamEnergy1+electron_mass_c2);
00240   
00241   gamma4vfinal.boost(bst);
00242   e4vfinal.boost(bst);
00243 
00244   gamDirection1 = gamma4vfinal.vect();
00245   gamEnergy1 = gamDirection1.mag(); 
00246   gamDirection1 /= gamEnergy1;
00247 
00248 
00249 
00250 
00251   fParticleChange->SetProposedKineticEnergy(gamEnergy1);
00252 
00253   if( gamEnergy1 > lowestGammaEnergy ) 
00254   {
00255     gamDirection1 /= gamEnergy1;
00256     fParticleChange->ProposeMomentumDirection(gamDirection1);
00257   } 
00258   else 
00259   { 
00260     fParticleChange->ProposeTrackStatus(fStopAndKill);
00261     gamEnergy1 += fParticleChange->GetLocalEnergyDeposit();
00262     fParticleChange->ProposeLocalEnergyDeposit(gamEnergy1);
00263   }
00264 
00265   eKinEnergy = e4vfinal.t()-electron_mass_c2;
00266 
00267   if( eKinEnergy > DBL_MIN ) 
00268   {
00269     // create G4DynamicParticle object for the electron.
00270     eDirection = e4vfinal.vect();
00271     G4double eFinMomMag = eDirection.mag();
00272     eDirection /= eFinMomMag;
00273     G4DynamicParticle* dp = new G4DynamicParticle(theElectron,eDirection,eKinEnergy);
00274     fvect->push_back(dp);
00275   }
00276 }

void G4HeatedKleinNishinaCompton::SetElectronTemperature ( G4double  t  )  [inline]

Definition at line 85 of file G4HeatedKleinNishinaCompton.hh.

References fTemperature.

00085 {fTemperature=t;};

Field Documentation

G4ParticleChangeForGamma* G4HeatedKleinNishinaCompton::fParticleChange [protected]

Definition at line 92 of file G4HeatedKleinNishinaCompton.hh.

Referenced by G4HeatedKleinNishinaCompton(), Initialise(), and SampleSecondaries().

G4double G4HeatedKleinNishinaCompton::fTemperature [protected]

Definition at line 94 of file G4HeatedKleinNishinaCompton.hh.

Referenced by G4HeatedKleinNishinaCompton(), SampleSecondaries(), and SetElectronTemperature().

G4double G4HeatedKleinNishinaCompton::lowestGammaEnergy [protected]

Definition at line 93 of file G4HeatedKleinNishinaCompton.hh.

Referenced by G4HeatedKleinNishinaCompton(), and SampleSecondaries().

G4ParticleDefinition* G4HeatedKleinNishinaCompton::theElectron [protected]

Definition at line 91 of file G4HeatedKleinNishinaCompton.hh.

Referenced by G4HeatedKleinNishinaCompton(), and SampleSecondaries().

G4ParticleDefinition* G4HeatedKleinNishinaCompton::theGamma [protected]

Definition at line 86 of file G4HeatedKleinNishinaCompton.hh.

Referenced by G4HeatedKleinNishinaCompton().

The documentation for this class was generated from the following files:
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