European Spallation Source
European Spallation Source ERIC (ESS) is a multi-disciplinary research facility under construction in Lund, Sweden. Its Data Management and Software Centre (DMSC) is in Lyngby, Denmark. Thirteen European countries are partners: the Czech Republic, Denmark, Estonia, France, Germany, Hungary, Italy, Norway, Poland, Spain, Sweden, Switzerland and the United Kingdom.
ESS is designed to help scientists study the structure and properties of materials across biology, chemistry, physics and engineering by using neutrons produced through spallation. This method generates more usable neutrons for a given amount of waste heat than traditional fission, and the ESS will operate as a long-pulse neutron source, enabling experiments that require weak signals, small samples or very short time scales.
Construction began around 2014, and ESS became a European Research Infrastructure Consortium (ERIC) in 2015. The project received a €50 million investment from the European Investment Bank, supported by InnovFin-EU Finance for Innovators. The total estimated cost is about €1.843 billion, with Sweden and Denmark each contributing roughly half.
The ESS site is near the MAX IV Laboratory, and the project relies on a linear accelerator to speed protons to high energies. These protons strike a rotating tungsten target wheel to produce neutrons, which are cooled and moderated by cryogenic hydrogen and room-temperature water. The resulting cold and thermal neutrons travel through neutron guides to experimental stations where researchers study materials at the atomic level.
About 15 instruments were planned for the facility, with some already completed: LOKI, BIFROST and ODIN in 2025, and DREAM, NMX and ESTIA expected in 2026. Most of the remaining instruments are planned to be ready by the end of 2027.
When operational, ESS will open its scientific user program in 2027. There have been discussions of future instrument plans and potential expansions, but some proposed projects, such as the ESSnuSB neutrino program, are not funded or currently planned.
This page was last edited on 3 February 2026, at 11:50 (CET).