Probing static and dynamic correlations in matter under extreme conditions: Concept of multi-purpose instrument at the European Spallation Source

Properties of neutrons, in particular high penetration depth for most materials, make them very powerful for studying matter under extreme conditions, e.g. high pressures or magnetic fields. A new generation of high power spallation neutron sources, such as the existing SNS and J-Parc and the coming ESS, brings neutron scattering in extreme environments to a completely new level. Indeed, measurements of smaller samples, use of more complex equipment and neutron instruments optimized for operation with extreme sample environment become readily available. The latter is actually one of the most important factors contributing to the field. In this paper a novel concept of an instrument for extreme environments at the ESS is presented. The main feature of the Extreme Conditions Instrument is its multi-purpose nature. It is not optimized for a single scattering technique but combines in a balanced way elastic (Diffraction and Small Angle Neutron Scattering) and inelastic capabilities. Such a concept enables effective combination of neutron scattering with a state-of-the-art sample environment independent of the complexity, dimensions and transportability of the latter. In addition, all available types of neutron experiments can be performed at the same thermodynamic conditions. The instrument concept has been verified by Monte-Carlo ray-tracing simulations and the results for instrument operation modes are compared with world-class instruments.