Introduction
The electromagnetic physics domain includes
Geant4 sub-packages
for simulation of electromagnetic (EM) interactions of charged particles,
gammas and optical photons.
In Geant4 physics interactions are described in term
of processes (G4VProcess interface) assigned to particle types.
EM processes usually have no applicability limitation by energy of media.
Physics tables with pre-computed cross sections, energy losses, ranges are build
by default from 0.1 keV to 100 TeV.
Basic EM processes utilizing model approach allowing to include one or several models
applied for different energy interval and geometrical region.
EM processes and models design for Monte Carlo simulation in High Energy Physics (HEP)
are developed and maintained by the
Electromagnetic Standard working group.
These models include
precise cross sections above 1 keV and default low limit on secondary particle production
is above 1 keV also. In the range of validity these models applicable also for use-cases outside
HEP.
The Low Energy Electromagnetic working group
is developing and maintaining processes and models more oriented
to medical, space science, and other non HEP applications. Tabulated cross sections for some models
are available from 10 eV. High energy limitation for low-energy models are different for different
physics interactions. In the energy range
from 1 keV to 1 GeV both standard and low-energy models are usually valid
and it is possible to perform detailed comparison of accuracy versus CPU performance of different models.
Physics processes configuration for Geant4 simulation is performed via Physics List.
Variants of Physics Lists are described in corresponding web pages and in Geant4 examples.
We encourage our users to learn Geant4 using these examples and to start their first applications
from examples. In case of problems we suggest to visit the HyperNews forum emprocesses
as the best way to exchange information.
