G3 to G4
Bremsstrahlung by e-/e+

Total cross section, Mean free path, dE/dX table

• Geant3
  S(E,Z,Ecut): parameterization from L.Urban, based on Berger-Seltzer formula, with dielectric suppression.
  dE/dX (E,Z,Tcut): - idem -
  10 keV - 100 GeV. Log(E) scale above 100 GeV
  

• Geant4 standard
  Adapted from Geant3
  Landau Pomeranchuk Migdal suppression effect.
  

• Geant4 low energy
  Subshell cross sections from EEDL data set.
  Energy limits: 250 eV - 100 GeV
  

Final state

• Geant3
  Gamma energy spectrum: parameterization based on Berger-Seltzer formula, with dielectric suppression.
  Gamma angle sampled from an energy-angle distribution derived from Tsai formula.
  

• Geant4 standard
  Adapted from Geant3
  LPM suppression effect
  

• Geant4 low energy
  Sample the gamma energy from a parameterized formula, where the coefficients are obtained from fits of EEDL gamma spectrum data.