Ln January 31, Emmanuel Macron, then on a state visit to Sweden, wandered between the immense infrastructures of the ESS (European Spallation Source), in Lund, in the far south of the country. This scientific research facility under construction, which is expected to become the most powerful neutron Source in the world, is co-funded by France, alongside 12 other European countries. With stars in his eyes but a deep voice, the President of the Republic pleaded for a “bolder” and “less regulated” Europe of industry and energy.
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And, when, less than three months later, we follow in his footsteps, we better understand his amazement in the face of such a research infrastructure. First of all, by its size, since it extends over nearly 75 hectares. By its 600 meter long proton accelerator, where particles are propelled at a speed close to that of light, then projected onto a 6,000 tonne tungsten target, which allows the explosion of atoms and the release of neutrons . But above all by his ambitions.
Exploring dark matter, fighting diseases and optimizing batteries
“Our neutron Source will allow researchers to make significant advances in fundamental physics by giving them the opportunity, for example, to explore dark matter,” enthuses Helmut Schober, its general director. In health, it will improve our knowledge of certain viruses to better combat them. In the energy sector, it will make it possible to study fuel cells and batteries to optimize their efficiency… For manufacturers too, this is a key issue, since neutrons are excellent detectors of weaknesses in materials produced”.
In short, these illustrations are only a few examples among others, because neutron beams can be of interest to many other researchers, such as archaeologists, who will be able to come with their fossils to analyze them and trace their origin without damaging them. Quantum researchers will be able, for their part, to try to unravel the mysteries of the still little-known world that they study, in particular to develop the computing of tomorrow.
But why are neutrons such good explorers of matter? Carrying no electric charge and having only weak interactions with matter, these particles have great penetrating power and are therefore excellent observers of the objects with which they interact, including certain light atoms, such as hydrogen. , which are not visible to time ranging from picoseconds (one thousandth of a billionth of a second) to microseconds (one millionth of a second).
A “racing beast”
Faced with the promises of such a project, it is impossible for France, which has one of the most seasoned scientific communities in this area, not to be part of it. Thus, the CEA and the CNRS are actively participating in the construction of 70% of the length of the accelerator and in the supply of 5 of the first 15 instruments that the ESS will host to launch its experiments.
“We are in the process of building a racing beast,” believes Marie-Hélène Mathon, head of the CEA’s material sciences research infrastructure and French representative on the ESS board, while regretting the delay in the project. “We hoped to have our first neutrons in 2019. Ultimately it will not be before 2025-2026. »
But what particularly worries the French scientific community is the progressive loss of sovereign neutron sources. “France concentrated 10% of global capacities in 2015. This figure should increase to 1% in 2033…” she regrets.
Indeed, the Orphée research reactor, inaugurated in 1980 in Saclay, which provided a beam of neutrons dedicated to the study of condensed matter, was definitively closed in 2019. “It was our national neutron Source, it contained 22 research instruments and allowed us to cultivate French excellence in this field,” insists the CEA researcher. The latter deplores a choice that is less a question of performance than a desire to denuclearize Saclay and concentrate investments in the European neutron project. “It was a key instrument both for research and for French industry. »
Neutron shortage in France
As bad news never comes alone, the Laue-Langevin Institute (ILL), a European neutron Source based in Grenoble, will also close its doors between 2030 and 2033. Until then, it offered the most intense neutron beams to the world and around forty high-tech scientific instruments with the aim of carrying out research of excellence.
“It was our last available Source in France. After its closure, we will be totally dependent on the ESS,” fears Marie-Hélène Mathon, emphasizing in passing that Germany, the United Kingdom and Switzerland retain their sovereignty. Not to mention the progress in American and Asian capacities in terms of neutron production…
We no longer have anything in France to train our scientists and maintain our skills in neutronics.Marie-Hélène Mathon, head of Material Sciences research infrastructures at the CEA
And the ESS will not be able to absorb this shortage of neutrons. “It’s good to have high-power sources like that of the Swedish installation, but we no longer have anything in France to train our scientists and maintain our skills in neutronics, meet the needs of our industrialists and clear our research topics through preparatory experiments. We need a small or medium range Source. »
The French neutronics scientific community, which has no less than 1,500 researchers and 300 laboratories, is playing its latest card, “ICONE”. Imagined by the CEA and the CNRS, this project consists of building an accessible Source – 150 million euros, compared to the 3.7 billion euros of the ESS – and compact, which would fit into a building of 70 square meters, each component of which (accelerator, target, etc.) would be doped to maximize neutron production.
The project was submitted to the Ministry of Higher Education, Research and Innovation. The decision to build or not this national Source should be taken in 2025. A favorable opinion would allow the production of the first neutrons in early 2030, according to Marie-Hélène Mathon: “I hope that the authorities will realize the importance of this sovereign project… We must not become the big losers in the race for neutrons. »
