Neutron sources for large scale user facilities: The potential of high current accelerator-driven neutron sources

Abstract

A review of neutron sources for large scale user facilities is provided, aimed at users of neutron sources who need to understand the characteristics and peculiarities of the different types of neutron sources in order to select the most suitable source for their needs and to optimize their experimental setups for their specific scientific requirements. To this end, we provide an overview of (i) the main nuclear processes used at user facilities to release neutrons from nuclei, namely fission, spallation, and low-energy nuclear reactions, (ii) the various possibilities to tailor the time structure and spectrum of free neutrons, from pulsing to moderation, (iii) the mechanisms to extract and transport neutron beams with desired properties in terms of flux, brilliance/brightness, spectrum, pulse shape, etc., (iii) the applications and related experimental requirements in major scientific fields, with emphasis on those with a larger user community, (iv) the technology and realization of research reactors and neutron spallation sources, and (v) the progress made in Compact Accelerator-driven Neutron Sources (CANS), but especially in High Current Accelerator-driven Neutron Sources (HiCANS).

HiCANS are the focus of the current review, as this entirely new type of facility could in the future play the role in the neutron ecosystem that national reactor-based sources have played in the past. As such, HiCANS do not aim for the highest neutron brightness, but rather for parameters such as resilience, reliability, flexibility, ease of access, minimization of radioactive waste, excellent signal-to-noise ratio and optimization of the price/performance ratio. These are key features needed to further expand the community of neutron users from science and industry to whom this review is addressed.