Introduction to Gamma Processes

All processes of gamma interaction with media in Geant4 happen at the end of the step, so these interactions are discrete and corresponding processes are following the G4VDiscreteProcess interface.

General Interfaces

There are a number of similar functions for discrete electromagnetic processes and for electromagnetic (EM) packages an additional base classes were designed to provide common computations [eal09]. Common calculations for discrete EM processes are performed in the class G4VEmProcess. Derived classes (Table 1) are concrete processes providing initialisation. The physics models are implemented using the G4VEmModel interface. Each process may have one or many models defined to be active over a given energy range and set of G4Regions. Models are implementing computation of energy loss, cross section and sampling of final state. The list of EM processes and models for gamma incident is shown in Table 1.

Table 1 List of process and model classes for gamma.

EM process

EM model

Ref.

G4PhotoElectricEffect

G4PEEffectFluoModel

PhotoElectric Effect

G4LivermorePhotoElectricModel

Livermore Model

G4PenelopePhotoElectricModel

Penelope Model

G4PolarizedPhotoElectricEffect

G4PolarizedPEEffectModel

Polarized Photoelectric Effect

G4LivermorePolarizedPhotoElectricModel

G4ComptonScattering

G4KleinNishinaCompton

Compton scattering

G4KleinNishinaModel

Compton scattering

G4LivermoreComptonModel

Livermore Model

G4LivermoreComptonModelRC

G4LowEPComptonModel

Monash University Low Energy Model

G4LowEPPolarizedComptonModel

Monash University Low Energy Model

G4PenelopeComptonModel

Penelope Model

G4PolarizedCompton

G4PolarizedComptonModel

Polarized Compton scattering

G4LivermorePolarizedComptonModel

Polarized Compton scattering

G4GammaConversion

G4BetheHeitlerModel

Gamma Conversion into e+e- Pair

G4BetheHeitler5DModel

Five-dimensional (5D) Bethe-Heitler gamma Conversion to e+e-

G4BetheHeitler5DModel

Pair production by Linearly Polarized Gamma Rays - Five-dimensional (5D) Bethe-Heitler Model

G4PairProductionRelModel

G4LivermoreGammaConversionModel

Livermore Model

G4LivermoreGammaConversion5DModel

Livermore Model

G4BoldyshevTripletModel

Livermore Triple Gamma Conversion

G4LivermoreNuclearGammaConversionModel

G4PenelopeGammaConversion

Penelope Model

G4PolarizedGammaConversion

G4PolarizedGammaConversionModel

Polarized Gamma conversion into an electron–positron pair

G4LivermorePolarizedGammaConversionModel

G4RayleighScattering

G4LivermoreRayleighModel

Livermore Model

G4LivermorePolarizedRayleighModel

G4PenelopeRayleighModel

Penelope Model

G4JAEAElasticScattering

G4JAEAElasticScatteringModel

JAEA Elastic Scattering Model

G4GammaConversionToMuons

Gamma Conversion into Lepton Pair

G4XrayReflection

X-ray reflection

Bibliography

eal09(1,2)

J. Apostolakis et al. Geometry and physics of the geant4 toolkit for high and medium energy applications. Radiation Physics and Chemistry, 78(10):859–873, oct 2009. URL: https://doi.org/10.1016/j.radphyschem.2009.04.026, doi:10.1016/j.radphyschem.2009.04.026.