Such large scale operations must necessarily come as a result of an extremely careful and public evaluation process which takes into account the real long-term needs of the fields concerned. A decision based on a democratic process is the key to its efficiency. The role of the government is to ensure the convergence of this process and to take the final decision. This position, albeit contributing to the discussion, cannot replace it. Yet this is what has happened several times already, in particular as far as synchrotron radiation sources are concerned.
Synchrotrons are sources of light with an extraordinary brilliance, ranging from infrared to X-rays.
Since light is the best probe for studying matter in all its states, these synchrotron sources have become an indispensable tool. In these centres work and meet scientists, as well as engineers and technicians, from the fields of biology, chemistry and physics, from the atomic to that of material sciences and geology, and also from industries such as petrochemical or pharmaceutical. There are about sixty of such sources worldwide. In the last few years the progress achieved in the design of multi-purpose sources with the highest performance has reduced the cost to a level compatible with national budgets, as Sweden Switzerland, Canada, Taiwan, South Corea, Italy and Germany have already realised. This is the type of source under discussion in France.