  A reliable and user-friendly characterisation of nano-objects in a target
material is presented here in the form of a software data analysis package for
interpreting small-angle X-ray scattering (SAXS) patterns. When provided with
data on absolute scale with reasonable uncertainty estimates, the software
outputs (size) distributions in absolute volume fractions complete with
uncertainty estimates and minimum evidence limits, and outputs all distribution
modes of a user definable range of one or more model parameters. A multitude of
models are included, including prolate and oblate nanoparticles, core-shell
objects, polymer models (Gaussian chain and Kholodenko worm) and a model for
densely packed spheres (using the LMA-PY approximations). The McSAS software
can furthermore be integrated as part of an automated reduction and analysis
procedure in laboratory instruments or at synchrotron beamlines.
