The UK's National Physical Laboratory (NPL) has signed a memorandum of understanding (MOU) with Switzerland-based CERN, the European Organisation for Nuclear Research (formerly Conseil Européen pour la Recherche Nucléaire). Under the MOU, NPL will join CERN's neutron time-of-flight facility (n_TOF) for studies intended to benefit advanced nuclear reactors, fuel cycles and nuclear fusion.

CERN’s n_TOF uses high-intensity neutron beams with a wide energy range to precisely measure neutron-related processes, including neutron-nucleus interactions. NPL intends to "perform accurate cross-section measurements of neutron induced nuclear reactions relevant to the development of new nuclear technologies" and will also seek to study reactions producing hydrogen, tritium and helium in a range of materials.” This will support “the development of tritium breeding blankets, plasma-facing armour components, and reactor component lifetime against radiation damage, all of which are key to the commercialisation of fusion”, NPL said.

Professor Paddy Regan, NPL Fellow in Nuclear and Radiation Science and Metrology, said: "The new formal agreement between CERN and NPL regarding the n_TOF collaboration should be a gamechanger in terms of the UK’s neutron research capabilities and impact. In particular, the proposed future international research programmes of relevance to next generation nuclear fission and fusion research are the cutting edge of this work internationally."

NPL hopes that there will be "more reliable simulation and operational understanding of next generation fission and fusion reactors" as a result of future experimental programmes at CERN. It will also work closely with Manchester, York, Surrey, Birmingham and Lancaster universities and the UK Atomic Energy Authority.

The wide energy range and high-intensity neutron beams produced at n_TOF are used to make precise measurements of neutron-related processes. To produce neutrons, a pulsed beam of protons from the Proton Synchrotron is directed at a lead target. When the beam hits, every proton yields about 300 neutrons. The initially fast neutrons are slowed down, first by a lead target, and then by a slab containing water. Some neutrons slow more than others as they pass through the targets, which creates a range of neutron energies.

Neutron time-of-flight measurements contribute in an important way to understanding nuclear data. Only a few time-of-flight facilities exist worldwide, each with its own characteristics. The strength of n_TOF is the large energy range it can cover, and the high number of neutrons per pulse.

Image: The 4π calorimeter inside the n_TOF experimental area (courtesy of CERN)