Plugging the neutron deficit

As Europe’s neutron supply could fall by as much as half within the next couple of decades, newly developed sources could stave off the decline

There are good reasons to get excited by the European Spallation Source (ESS), which is currently under construction in Lund, Sweden. When the machine finally goes online – and 2028 is the current completion date – it will be the world’s most intense particle accelerator, generating up to 100 times more neutrons than any of today’s sources. Like a giant microscope, it will allow unprecedented studies into various fields – particularly the science of the everyday, such as plastics, pharmaceuticals, biological matter and nanotechnology. The ESS is a fitting tribute to Europe’s neutron research community, which is estimated to be by far the world’s largest, comprising some 6,000 scientists and engineers.

Against this starry-eyed picture, a report published in March by the European Strategy Forum on Research Infrastructures (ESFRI), an EU body, makes for sobering reading. Europe’s neutron community has been fostered over time by a great network of small to large flux neutron sources, two thirds of which were built in the 1960s and 1970s. The majority of these sources are set to close within a decade, and several smaller research reactors have been decommissioned already – those at the Risø National Laboratory in Denmark (in 2000), at Forschungzentrum Jülich (in 2006) and at Gessthacht in Germany (in 2010). Two of the biggest sources – the Orphèe reactor at the Laboratoire Léon Brillouin (LLB) in Saclay, France, and the BER-II reactor at the Helmholtz-Zentrum Berlin in Germany – are expected to close down within four years. By the mid 2030s, according to the ESFRI’s Roadmap, the best-case scenario is a 30% drop in neutron instrument time. The worst-case scenario: a 50% drop.

Simply put, in decades to come the ESS may be a transformative neutron source, but there may not be much of a neutron community left to use it. “The renewal of intermediate neutron sources becomes necessary to maintain a ‘critical mass’ for the neutron user community, otherwise new powerful sources such as the ESS become almost useless,” says Jacques Ollivier, a physicist at the world’s current leading neutron facility, the Institut Laue-Langevin (ILL) in Grenoble, France. The ILL itself is set to close in 2023 unless its partners agree otherwise. […]

To read the rest of this article, please contact Jon Cartwright for a pdf.