  Realistic simulations of experiments at large scale photon facilities, such
as optical laser laboratories, synchrotrons, and free electron lasers, are of
vital importance for the successful preparation, execution, and analysis of
these experiments investigating ever more complex physical systems, e.g.
biomolecules, complex materials, and ultra-short lived states of highly excited
matter. Traditional photon science modelling takes into account only isolated
aspects of an experiment, such as the beam propagation, the photon-matter
interaction, or the scattering process, making idealized assumptions about the
remaining parts, e.g.\ the source spectrum, temporal structure and coherence
properties of the photon beam, or the detector response. In SIMEX, we have
implemented a platform for complete start-to-end simulations, following the
radiation from the source, through the beam transport optics to the sample or
target under investigation, its interaction with and scattering from the
sample, and its registration in a photon detector, including a realistic model
of the detector response to the radiation. Data analysis tools can be hooked up
to the modelling pipeline easily. This allows researchers and facility
operators to simulate their experiments and instruments in real life scenarios,
identify promising and unattainable regions of the parameter space and
ultimately make better use of valuable beamtime.
  This work is licensed under the Creative Commons Attribution 3.0 Unported
License: http://creativecommons.org/licenses/by/3.0/.
