Toy model used for testing various sample components for solution-SAXS
mimicking the geometry of the BM29 beamline at ESRF:
https://www.esrf.fr/home/UsersAndScience/Experiments/MX/About_our_beamlines/bm29/beamline-specifications.html
Note that this model does not include much of the beamline optics, instead it emulates their effect
by settgin relevant beam parameters from a model source.
Input parameters
Parameters in boldface are required;
the others are optional.