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Default - emstandard The default EM constructor (G4EmStandardPhysics) is used in major part of reference Physics Lists (QGSP_BERT, QGSP_BIC, FTF_BIC, FTFP_BERT, ...).
Option 1 - emstandard_opt1 is designed for HEP productions, it is used in the QGSP_BERT_EMV reference Physics List. The corresponding physics constructor (G4EmStandardPhysics_option1) 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.
Option 2 - emstandard_opt2 designed for HEP applications, it is used in the QGSP_EMX reference Physics List. The corresponding physics constructor (G4EmStandardPhysics_option2) includes following modifications with respect to the default EM physics:
- the option "ApplyCuts" is used enabling kill of electrons and gammas produced below production thresholds for all EM processes;
- specialized process for muon multiple scattering is used, this process takes into account small angle scattering (below 0.2 rad), for large scattering angles the single scattering process is used.
Option 3 - 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. The corresponding physics constructor (G4EmStandardPhysics_option3) 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 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 ions 0.02 mm.
Physics Lists of Geant4 examples - 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.
- livermore The physics constructor (PhysListEmLivermore) with low-energy electromagnetic processes for gamma, e-, hadrons and ions based on Livermore data sets.
- peneloper The physics constructor (PhysListEmPenelope) with low-energy electromagnetic processes for gamma, e-, hadrons and ions based on Penelope models.
- standardSS The physics constructor (PhysListEmStandardSS) in which multiple scattering process is substituted by single scattering.
- standardNR The physics constructor (PhysListEmStandardNR) in which multiple scattering processes for protons and ions are substituted by single scattering process.
- standardICRU73 The physics constructor (PhysicsList) in which a model of ion ionisation based on ICRU'73 data is used.
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