Advantages of the concept

The supply of neutron beams currently barely meets the needs of science and industry. In addition, some neutron sources based on nuclear fission will reach the end of their operating life in the next decade. The High Brilliance Neutron Source (HBS) would make an essential contribution to ensuring reliable, easy access to neutron beams for German and European researchers. It works on a different concept than existing large neutron sources.

In research reactors, nuclear fission takes place as a controlled chain reaction: when a neutron hits a uranium atom nucleus, it breaks apart and neutrons are released, some of which then go on to split new nuclei.

Unlike research reactors, the planned HBS does not require nuclear fuel. This makes disposal much easier: although the metal target and the walls surrounding it become radioactive when bombarded with protons, this radioactivity has almost completely dissipated after around ten years. In addition, the volume of the activated target is small.

The HBS can be shut down at any time because there is no chain reaction. Furthermore, because no nuclear fuels are used, scientists have much easier access to their measuring instruments and measurements. Numerous regulations and safety measures prescribed by the Atomic Energy Act do not apply.

In addition to research reactors, there are also spallation sources. The European ESS, currently under construction in Sweden, is one such type of neutron source. Similar to the HBS, protons in spallation sources bombard the atomic nuclei of heavy metals. However, the protons have much higher energy than those in the HBS because they have been accelerated to almost the speed of light in huge facilities. The proton bombardment energises the atomic nuclei in the target of the spallation source to such an extent that they literally vaporise, releasing neutrons. On average, 20 neutrons are produced per proton.

A major advantage of HBS over spallation sources lies in the more efficient use of the released neutrons due to their lower energy: a larger proportion of the neutrons can be used for experiments, while fewer neutrons are absorbed by the surrounding walls. This simplifies the disposal of the neutron source and the shielding components, as they become less radioactive than those in spallation sources.

Another advantage of the HBS is that the neutron beam can be tailored to the requirements of the particular scientific research project. The pulse lengths of the neutron beam and their frequency are variable and can be directly adapted to the instrument requirements. In addition, the energy of the neutrons can be individually adjusted for each measuring instrument using optimised moderators.

Unlike other neutron sources, the HBS has a modular design, which facilitates maintenance and repair work. Technicians can replace individual modules without shutting down the entire operation for long periods of time. As technology advances, improved modules can be integrated quickly and efficiently.