Neutrons are us!

The European Spallation Source, ESS, is an accelerator-based neutron source, currently being built in Lund, Sweden. When in full operation, it is expected to host some 800 experiments and 3000 scientists every year. It is a long-pulse source, where neutrons are produced from protons directly from a linear accelerator, rather than being compressed in a accumulator ring. This allows a higher flux of protons at a given cost, while short pulses can be obtained through the use of choppers. The accelerator, which will reach 5 MW of beam on target when completed, is unique in that both design and construction have been done by a pan-European collaboration of no less than 22 institutes and universities, now also taking part in installation, testing and commissioning in Lund. The paper describes this accelerator collaboration and the components contributed from the different partners.