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The thermal moderator is the key component in a research neutron source to convert the primary neutrons which typically have energies in the MeV regime into useful neutrons for investigations with energies well below 1 eV. In the case of a HiCANS as HBS, the thermal moderator has to be optimized according to the compact target size and to the proton pulse lengths at individual target stations. Here, the details of a thermal moderator design serving up to 12 instruments at a target station and its neutronic performance are presented. The thermal moderator consists of a complex aluminium vessel filled with light water as moderator material containing 12 thin-walled extraction channels arranged in 2 levels.

High Current Compact Accelerator-driven Neutron Sources (HiCANS) have recently emerged as a possible solution to the drop in neutron provision in Europe due to the closure of several research reactors. Within this new trend, the Laboratoire Léon Brillouin (LLB) is currently assessing the performance of neutron techniques around this novel type of source. HERMES is a time-of-flight horizontal reflectometer that was operated by the LLB at the ORPHEE reactor until 2019 and was dedicated to soft matter studies. Through a collaboration with the Jülich Centre for Neutron Science, HERMES was installed in 2022 at the JULIC Neutron Platform (JNP) at the Forschungszentrum Jülich. This platform is able to deliver neutron pulses in the 100 μs - 2 s range and is very well suited to evaluate the feasibility of reflectivity experiments at a HiCANS. Since its installation and first tests in 2022, several improvements have been implemented at HERMES. Our current goal is to perform reflectivity experiments with large neutron mirrors as a proof of concept, as the flux at the JNP is several orders of magnitude lower than the original ORPHEE flux or the one expected at a HiCANS. Nevertheless, Monte Carlo simulations show that an instrument as HERMES operating at a HiCANS could match the performance of similar instruments at research reactors and spallation sources.

High Current Accelerator driven Neutron Sources (HiCANS) are a cost-efficient alternative for future large scale neutron facilities. They excel in transforming neutrons released by the primary nuclear reaction into a spectral range usable for applications. In particular, the cost of a target station represents only a minor fraction of the overall construction cost due to the lower energy of the primary neutrons, which requires less shielding. They can be designed to provide optimized pulse and spectral properties for applications in neutron scattering, analytics and imaging experiments. For the High Brilliance neutron Source (HBS) project at Forschungszentrum Jülich, we have developed a modular design that meets the radiation protection requirements while providing sufficient space in its core to adapt the target-moderator-reflector assembly to the different applications. In the following, we present the basic target station design which will be used at HBS for three different realizations with their own instrument suite. All relevant components have been designed, built and tested at the JULIC Neutron Platform which has produced neutrons since December 12th 2022. The simulated performance of a target station shows that the brightnesses of the moderators are in the range of modern research reactors and sub-MW power spallation sources.

HERMES is a time-of-flight reflectometer that operated at the Orphée reactor until 2019. In 2022, HERMES was installed at the JULIC (Jülich Light Ion Cyclotron) Neutron Platform as part of a collaboration between the Laboratoire Léon Brillouin and the Jülich Centre for Neutron Science. The main goal of the current setup is to probe the viability of neutron instrumentation at a High Current Compact Accelerator-driven Neutron Source (HiCANS). As the flux at the JULIC neutron platform is several orders of magnitude lower than the original Orphée flux or the expected flux for a HiCANS, our current objective is to perform reflectivity experiments with supermirrors as a proof of concept. Nevertheless, Monte-Carlo simulations showed that the HERMES instrument’s performance at a HiCANS such as HBS or ICONE could match that of reflectometry instruments operating at research reactors or spallation sources. An experiment with a supermirror carried out in December 2022 allowed us to preliminary prove the feasibility of this kind of experiments at an accelerator-driven neutron source.