Virtual Instrumentation Tool for Neutron Scattering at Pulsed and Continuous Sources
Welcome to the homepage of the VITESS program! VITESS is a tool for simulation of neutron scattering instruments for neutron scattering at pulsed and continuous sources. Using VITESS, you can simulate a large variety of instruments at all major current and future neutron sources, including the European Spallation Source (www.esss.se), which is currently being designed. VITESS is supported by a graphical user interface (GUI), making it simple for you to compose your instrument and run simulations. You can use VITESS on a Windows, Linux or Macintosh computer. Simply choose the appropriate download file on the right and install VITESS on your computer. The VITESS installation includes some example instruments to demonstrate the main features of the program. You can also use the examples as an initial aid for your own instruments. For any questions and feedback of all kind you may contact the VITESS developers team, vitess@helmholtz-berlin.de, and we will help you as quickly as possible.
Concept of VITESS
The simulation of a neutron instrument comprises several modules, which represent instrument components like guides or detectors, various helper modules, e.g. frames modifying the coordinate system between two instrument components, and modules for data visualisation and evaluation. All modules can be selected within the GUI. When you run a simulation, such modules are co-working sequentially embedded in a pipe structure:
Each module processes and then passes neutron data to the following one.
The first module must be either a neutron source module, or it must read information about the neutron trajectories from a file typically created in an earlier simulation of the preceding part of your instrument, which includes the source module.
The last module may be set up to write a file of neutron trajectories. This makes sense if you wish to use these trajectories in further simulations as input, e.g., for future studies of parameter distributions of these neutrons.
VITESS has thus a modular structure consisting of independently executable program components (e.g. source, guide, chopper, polarizer, sample, focussing monochromator/analyser, etc). Each module processes the neutron beam input and the output neutron beam is a function of the parameters chosen for that respective module. For example, the number of neutrons that are lost in a guide segment depends on its geometry parameters and the coating of its surfaces.
The neutron beam input and output represent an optionally large number of neutron trajectories each of which is described by 12 coordinates:
time, lambda, probability weight, position (x, y, z), direction (cos(alpha), cos(beta), cos(gamma)) and Spin (S_x, S_y, S_z)
These 12 parameters per neutron trajectory are consecutively written to or read from the stream in a double precision binary form. By sticking to some conventions you can not only use the provided executables, but also write and add your own ones in order to study the characteristics of the neutrons anywhere in your instrument according to your needs. To understand how your modules fit to the framework you may read the report on VITESS Software Technique (PDF).
Version History
Publications on VITESS (via Google Scholar)
A view of the VITESS GUI including two diagrams created in the simulation.
Team of Developers
To improve and adopt the VITESS software to a broader base we invite volunteers to join team of contributing developers. If you have written your own module that you would like to share with the public, you are welcome to provide us the code by sending this to the mailing list vitess@helmholtz-berlin.de. We will put your code and help information indicating the author's name. We only require that components that are destined for an official release are thoroughly tested and that you feel responsible for your module for at least a certain time. This is to ensure the quality and usability of yearly official releases.
Permanent: Michael Fromme, Andreas Houben, Klaus Lieutenant, Sergei Manoshin, Daniil Nekrassov, Carolin Zendler
Contributing: Mirko Boin, Leo Cussen, Jennifer Schulz
For support or information please contact the team of developers at vitess@helmholtz-berlin.de
VITESS has been partly supported by the SCANS network (FP5) and was supported by the NMI3-MCNSI Network (FP6) within the Research Infrastructures Activities of the Research and Technology Development Programme of the European Commission. It is currently part of the german in-kind contribution to the ESS project(WP K7).
