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The Computing for Science (CS) group supports ILL scientists, students and visitors in a number of activities including data analysis, instrument simulation and sample simulation.

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Computing for Science and the Computation Lab

The Computing for Science (CS) group supports ILL scientists, students and visitors in a number of activities including data analysis, instrument simulation and sample simulation.


Presentation by Mark Johnson at the Scientific Council, April 2009
    Computing for science & computation-lab: past, present and future

Data Analysis

 A range of programs written in Fortran, Java, Matlab and IDL are developed and supported by CS. These codes are freely available and can be downloaded. We are also working with the Instrument Control group on the progressive introduction of a common, neutron scattering and X-ray, data format, NeXus. We also provide a Live DVD which contains many scientific applications pre-installed on the DVD. A comprehensive list of all the CS programs is available on the software page

Instrument simulations

The CS offers two types of software for instrument simulations:

 Monte Carlo Ray Tracing: They are mainly of interest to instrument scientists wanting to improve existing instruments or to design new instruments. The most widely used simulation code, McStas, is jointly developed in CS and in Risoe.

Virtual experiments represent an advanced way to use McStas, when including complex instrument descriptions, with samples and their environment. Such models enable to realistically reproduce the actual experiment measurements, and analyze the signal in terms of coherent and incoherent scattering, elastic and inelastic processes, multiple scattering, self shielding, ...

 In between data analysis and instrument simulations, we have developed real space <-> reciprocal space instrument simulators. The vTAS suite (vTAS, vIMPS, vUFO) provides graphical assistance to prepare and perform inelastic neutron scattering experiments on a TAS-type instrument, including latest multiplexed instrumental configurations, such as FlatCone, IMPS and UFO. When installed with McStas, it is possible to visualize the instrument resolution function.

Last, we also publish a complete ILL beam-line analysis database obtained by coupling MCNP and McStas. Our ILL RHF reactor model produces capture flux in agreement with gold foil measurements, over the whole facility. Detailed information is given for selected beam lines (flux, divergence, beam image, brightness, ...).

McStas instrument models for TAS and crystal TOF spectrometers can be coupled with a neutron instrument LEGO (c) model, that moves when performing simulations according to the instrument configuration.


As samples studied by neutron scattering become more complex, atomistic sample simulations offer the possiblity of calculating neutron scattering spectra and profiles and providing detailed models, which allow experimental data to be more fully exploited. Classical and ab initio simulations can be performed on a wide range of systems. Simulations are performed mainly on local PC clusters, which are operated in collaboration with the IT group.

The Computation Lab (C-Lab) hosts scientists and students wanting to perform instrument and sample simulations and allows a broad spectrum of experience and tools to be brought together where the experiments are performed. From September 2007 simulations support can be requested along with neutron beamtime and accepted simulation work is performed by visitors in collaboration with the C-Lab.


The CS is also involved in the development of multimedia presentations of many aspects of ILL's life and facilities. This comprises the ILL Virtual Tour, CD-roms, movies, 3D animations such as Neutrons4Science or vDiffraction, 2D animations and PowerPoint or Keynote presentations. For conferences and teaching purposes (workshops, neutron schools, training) we propose to build TAS and TOF LEGO (c) instrument models that can be controlled with McStas.

Partner groups

Scientific Software, ESRF, Grenoble, France

Cluster and computers

SI and CS manage a computational cluster


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This site was ported to Typo by Sylvie Crozel (2007). Updated by A.Filhol (11 Jan. 2011).