The Virtual Instrumentation Tool for the ESS (VITESS) is an open source software package for the simulation of neutron scattering experiments.
The software is maintained and developed by the Forschungszentrum Jülich (FZJ),[1] and available for Windows, Linux and Macintosh on the VITESS homepage.
It comprises all established instrument hardware such as neutron optics (e.g. guides, apertures, lenses), wavelength selectors (e.g. disc choppers, velocity selectors) and a growing variety of samples, allowing to perform virtual experiments including sophisticated setups like polarized neutrons in magnetic fields.
[9][10] Other simulation packages for neutron scattering instruments include McStas, Restrax, NISP and IDEAS.
Each neutron is assigned a count rate which is modified on each interaction with the instrument, like the reflection at or transmission through a (super)mirror plate.