  Several models for the simulation of photon elastic scattering are
quantitatively evaluated with respect to a large collection of experimental
data retrieved from the literature. They include models based on the form
factor approximation, on S-matrix calculations and on analytical
parameterizations; they exploit publicly available data libraries and
tabulations of theoretical calculations. Some of these models are currently
implemented in general purpose Monte Carlo systems; some have been implemented
and evaluated for the first time in this paper for possible use in Monte Carlo
particle transport. The analysis mainly concerns the energy range between 5 keV
and a few MeV. The validation process identifies the newly implemented model
based on second order S-matrix calculations as the one best reproducing
experimental measurements. The validation results show that, along with
Rayleigh scattering, additional processes, not yet implemented in Geant4 nor in
other major Monte Carlo systems, should be taken into account to realistically
describe photon elastic scattering with matter above 1 MeV. Evaluations of the
computational performance of the various simulation algorithms are reported
along with the analysis of their physics capabilities.
