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vUFO is an instrument simulator for the multiplexed TAS instrument IN12-UFO. It makes it possible to experiment various measurement strategies through free or predefined instrument configurations. vUFO is part of the vTAS suite.

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vUFO - Virtual IN12-UFO instrument

by Wolfgang Schmidt and Yannick Raoul.


vUFO is an instrument simulator for the CRG multiplexed Three-Axis-Spectrometer IN12-UFO. Its is part of the vTAS suite (see below) written in Java.

UFO (Universal Focusing Option) is a multi-analyser (15 blades) and multi-detector system, an option which can be installed on the cold TAS IN12.

Multiplexed TAS instruments make assessing a measurement strategy very difficult without a computer assistance. This is especially true with UFO and its 46 degrees of freedom (rotation, translation, spacing of the blades and slit positionning).

vUFO implements a dual real space and reciprocal space interactivity which much facilitates the understanding of the behavior of the instrument and its limits. It makes it possible to experiment various measurement strategies through free or predefined instrument configurations. This proved to be valuable tools for both instrument responsibles and users, and also for teaching.

vUFO implements instrument resolution calculation with the Cooper Nathan's method. A yet untested McStas like Monte Carlo approach is also available but only for the bundled version.

vUFO is still in the development phase since in 2013 the instrument UFO was still operated in the test mode. The current version of the program is used as an help to experimenting new measurement strategies. Once thoroughly tested by scientists these will be implemented in the application as "predefined" instrument strategies. In other words, the features of the application are not yet frozen and are consistent with our current understanding of the capabilities of the TAS option UFO.

Ref: "The vTAS suite: a simulator for classical and multiplexed three-axis neutron spectrometers"

       M. Boehm, A. Filhol, Y. Raoul, J. Kulda, W. Schmidt, K. Schmalzl,
       Nuclear Inst. and Methods in Physics Research, A (2013) 697, 40-44.

The vTAS suite is now a single application vTIU regrouping three TAS simulators:

  • vTAS: classical TAS geometry and multiplexed geometry of FLATCONE
  • vIMPS: multiplexed geometry of IN8-IMPS
  • vUFO: multiplexed geometry of IN12-UFO

An early version of vTAS was developped by Alain Bouvet in 1998.
The current vTAS project was funded by the ILL and NMI3.

Running the application

Warning: vUFO is a prototype application since the instrument UFO is not yet commissioned.
Requires Java 2 v1.6 or higher. Make sure that is installed and activated. On some computers you may also need to clear the Java cache.
The JNLP mechanism will give you the opportunity to install a standalone version of the application on your hard drive.
Prior installing a new version of vUFO it is recommended to delete the old preference files.
     E.g. for OS X users, delete folder ~/Library/Preferences/ILL/vUFO.
Release date: 26 Feb 2013.

Click HERE to launch vUFO v0.9

Report bugs to forge.epn-campus.eu

Mac users should read this : OS X 10.9 or higher, Safari 6 or higher !

Special keys and options

Here what you need to know for a good experience with the vUFO interface:

  • Instrument and scattering panes

    • right click+drag: paning
    • [Mac OS X] cmd-key+click+drag: paning
    • mouse wheel: zoom in/out at mouse position

  • Instrument resolution function (only for the bundled-vUFO version, not for the web version)
    First, put the focus on the reciprocal space pane, then:
    • The R key will launch a McStas-like Monte Carlo simulation. The calculation may take several seconds, be patient ! (Warning: this is an unverified option)
    • The BS key will erase the plot


vUFO is a free application. Use it at your own risks. Neither the authors nor the ILL endorse or accept any responsibility for problems or wrong results you may obtain with it. No support is provided but feedback is warmly welcome -> <schmidt(at)ill.eu> or <filhol(at)ill.eu>.

Updates: 20 Jan 2011, 13 March 2013, A.Filhol <filhol(at)ill.eu>