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.