McXtrace - An X-ray ray-trace simulation package

11  SasView/sasmodels form factors: small-angle scattering

This chapter documents the sasmodels category: a large set of small-angle scattering (SAXS/USAXS) form-factor models, generated automatically from the open-source SasView/sasmodels project (https://github.com/SasView/sasmodels) and exposed to McXtrace as individual SasView_* components (each wrapping one sasmodels kernel). This gives access to the same, actively maintained library of scattering-law implementations used for SAXS/SANS data fitting in SasView itself, directly as McXtrace sample components, without needing to hand-implement each form factor.

Most models exist in a plain (orientation-averaged, i.e. powder/isotropic) form and, where the shape has a well-defined orientation, an _aniso variant that additionally accepts orientation parameters. For the underlying physics of any individual model (defining equation, parameter meaning, validity range), consult the corresponding page in the SasView documentation (https://www.sasview.org/docs/); the parameter tables below are generated directly from each component’s McDoc header and give the McXtrace-specific parameter names, units and defaults.

See also the contrib chapter’s native (non-SasView-derived) SAXS sample models (SAXSSpheres, SAXSCylinders, …) for an alternative, McXtrace-specific implementation of many of the same shapes.