In a spallation neutron source, such as the European Spallation Source (ESS), an accelerator drives particles known as protons at near the speed of light into a rotating target. In the nuclei of the atoms in this target, neutrons are liberated by the incoming protons before being reduced to a precise range of speeds by a device called a moderator. The moderator is therefore the source of neutrons, although to reach the scientific experiments the particles must be transmitted by a neutron reflector.
In the current design of the ESS, there is space for a second moderator on the opposite side of the target to the first. One of the HighNESS work packages (WP4) aims to produce a design for this second moderator (as well as any others required for colder neutrons), while another (WP6) aims to produce a design for an advanced reflector. However, there is much more to the design of a second ESS source than these goals.
The performance of the moderators and the reflector must be tailored to the needs of condensed-matter science (WP7) and fundamental physics (WP8). Meanwhile, the designs must be guided by new software (WP2) and material-characterization experiments (WP3) that describe neutron behaviour in these unprecedented regimes, and be turned into workable blueprints by engineers (WP5).
On top of that, there is the necessary support of a cloud computing infrastructure (WP9) and project management (WP1), and the need to disseminate progress to the general public (WP10).