G4LECS
GEANT4 Low-Energy Compton Scattering Package

G4LECS is an extension program for the GEANT4 simulation package that incorporates detailed physics into the simulation of Compton and Rayleigh scattering. In standard GEANT4, the free electron approximation is used for Compton scattering, and Rayleigh scattering is ignored. The G4LowEnergy extension package included in the GEANT4 distribution corrects the Compton cross sections and for bound electron momentum, but does not account for the resulting changes in the scattered particle energies (known as Doppler broadening). Furthermore, there are errors in the treatment of Rayleigh scattering.

These problems lead to significant errors in simulating photon scattering at energies near/below several hundred keV. The G4LECS treatment of Compton scattering accounts for bound electron momentum on a shell-by-shell basis using evaluated data read from tables. For Rayleigh scattering, G4LECS uses evaluated coherent scattering cross section and form factor data read from tables.

G4LECS was designed to be used transparently with any GEANT4 application. It is particularly useful for simulating advanced Compton telescopes, where the fine position and energy resolution make the inclusion of Doppler broadening crucial for realistic simulations. For more details and installation instructions see the README file below.

Note the the present release of G4LECS does NOT account for the polarization-dependence of the scatter angle distributions. A future release of G4LECS will include polarization effects.

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Author: R. Marc Kippen Last modified: Jun 30 2006