Physics Lists EM constructors in Geant4 9.5

• Default
• Option1
• Option2
• Option3
• Livermore
• Liveermore with polarisation
• Penelope
• DNA physics
• Physics Lists of Geant4 examples

• emstandard The default EM constructor is used in major part of reference Physics Lists (FTFP_BERT, FTF_BIC, QGSP_FTFP_BERT, QGSP_BIC, ...). In comparison with previous Geant4 versions the following models are default in 9.5:
  • G4UrbanMscModel95 for multiple scattering of e+ and e-;
  • G4WentzelVIModel for multiple scattering of mu+ and mu- combined with G4eCoulombScatteringModel for large angle scattering;
  • G4SeltzerBergerModel for e+ and e- bremsstrahlung;
  • G4PEEffectFluoModel for photo-elecric effect.

• emstandard_opt1 is designed for HEP productions (CMS focused), it is used in the FTFP_BERT_EMV, QGSP_BERT_EMV, QGSP_BERT_EML, LHEP_EMV reference Physics Lists. The corresponding physics constructor includes following modifications for electron and positron transport with respect to the default EM physics:
  • the option "fMinimal" is used for multiple scattering step limitation, which provides accuracy and CPU performance similar to that of the Geant4 version 7.1p02;
  • the parameter dRoverRange used in computation of step limit by the ionisation process is set to the value 0.8.
  • the ApplyCuts option is enabling production thresholds (cuts) on secondary particles for all EM processes including photoelectric effect, Compton scattering, gamma conversion, positron annihilation.

• emstandard_opt2 is designed for HEP productions (LHCb focused), it is used in the FTFP_BERT_EMX and QGSP_BERT_EMX reference Physics Lists. The corresponding physics constructor includes following modifications for electron and positron transport with respect to the default EM physics:
  • G4UrbanMscModel93 is used for e+ and e- for backward compatibility (the default model is G4UrbanMscModel95);
  • the option "fMinimal" is used for multiple scattering step limitation, which provides accuracy and CPU performance similar to that of the Geant4 version 7.1p02;
  • the parameter dRoverRange used in computation of step limit by the ionisation process is set to the value 0.8.
  • the ApplyCuts option is disabled.
  • Alternative G4Generator2BS angular generator is used for the bremsstrahlung process.

• emstandard_opt3 designed for any applications required higher accuracy of electrons, hadrons and ion tracking without magnetic field. It is used in extended electromagnetic examples and in the QGSP_BIC_EMY reference Physics List. The corresponding physics constructor includes following modifications:
  • the option "fUseDistanceToBoundary" for multiple scattering of electrons and positrons;
  • increased number of bins in physics tables - 220 (84 bins by default);
  • the parameter dRoverRange used in computation of step limit by the ionisation process is reduced with respect to the default value 0.2: 0.1 for alpha, He3, ions;
  • the parameter finalRange used in computation of step limit by the ionisation process is reduced with respect to the default value 1 mm: for e+,e- is 0.1 mm, for muons, pions, proton is 0.05 mm, for alpha and He3 0.01 mm, for ions 0.001 mm;
  • G4KleinNishinaModel is used for the Compton scattering simulation which include Doppler broading and allowing to simulate atomic deexcitation: fluorescence and Auger electron production. Atomic deexcitation may be enabled via UI commands - see extended electromagnetic examples;
  • G4IonParametrisedLossModel is used for ion ionisation, this model is based on ICRU73 ion stopping data;
  • G4RayleighScattering process is used with the default Livermore Rayleigh scattering model;
  • G4NuclearStopping process is used for alpha, He3, ions.

• emlivermore designed for any applications required higher accuracy of electrons, hadrons and ion tracking without magnetic field. It is used in extended electromagnetic examples. The corresponding physics constructor includes following modifications compared with the G4EmStandardPhysics_option3.cc:
  • G4LivermorePhotoElectricModel for gamma below 1 GeV;
  • G4LivermoreComptonModel for gamma below 1 GeV;
  • G4LivermoreGammaConversionModel for gamma below 1 GeV;
  • G4LivermoreIonisationModel for e- below 100 keV;
  • G4LivermoreBremsstrahlungModel for e- below 25 MeV;
  • Fluorescence is enabled by default.

• emlivermore_polar designed for any applications required higher accuracy of electrons, hadrons and ion tracking without magnetic field. It is used in extended electromagnetic examples. The corresponding physics constructor includes following modifications compared with the G4EmStandardPhysics_option3.cc:
  • G4LivermorePolarizedPhotoElectricModel for gamma below 1 GeV;
  • G4LivermorePolarizedComptonModel for gamma below 1 GeV;
  • G4LivermorePolarizedGammaConversionModel for gamma below 1 GeV;
  • G4LivermorePolarizedRayleighModel for gamma below 1 GeV;
  • G4LivermoreIonisationModel for e- below 100 keV;
  • G4LivermoreBremsstrahlungModel for e- below 25 MeV;
  • Fluorescence is enabled by default.

• empenelope designed for any applications required higher accuracy of electrons, hadrons and ion tracking without magnetic field. It is used in extended electromagnetic examples. The corresponding physics constructor includes following modifications compared with the G4EmStandardPhysics_option3.cc:
  • G4PenelopePhotoElectricModel for gamma below 1 GeV;
  • G4PenelopeComptonModel for gamma below 1 GeV;
  • G4PenelopeGammaConversionModel for gamma below 1 GeV;
  • G4PenelopeRayleighModel for gamma below 1 GeV;
  • G4PenelopeIonisationModel for e+ and e- below 1 GeV;
  • G4PenelopeBremsstrahlungModel for e+ and e- below 1 GeV;
  • Fluorescence is enabled by default.

• emDNAphysics designed for any applications required higher accuracy of electrons, hadrons and ion tracking without magnetic field. It is used in extended electromagnetic examples. The corresponding physics constructor includes very low-energy processes for simulation of particle transport in liquid water. See more detail in Geant4-DNA pages.

• TestEm7 extended/electromagnetic example providing several variants of EM physics, which are also used in other Geant4 applications. This example can be recommended as a starting point for user customized Physics List.


• It is shown how to add G4BraggIonGasModel and G4BetheBlochIonGasModel on top of standard ionisation models using UI command "/testem/phys/addPhysics ionGasModels", which enables models via G4EmConfigurator; these model allowing to simulate ion transport with user defined change state and not to use ion effective charge;


• standardSS The physics constructor, in which multiple scattering process is substituted by single scattering.


• standardNR The physics constructor, in which multiple scattering processes for protons and ions are substituted by single scattering process.


• TestEm8 extended/electromagnetic example demonstrating how to activate PAI model per region using G4EmConfigurator. This method can be recommended for configuration of other models per detector region.