Henning Larsen, Cobe, and SLA deliver world-leading facility for neutron source

Henning Larsen, COBE, and SLA envisioned a village for an international community of scientists; a multitude of spaces allow visiting researchers from global science institutions to meet each other informally both indoors and outdoors, including pathways for walking and jogging and rainwater ponds. A nature-based "fenceless" landscape with specially designed sunken "ha-ha" fences and diverse vegetation keeps the facility secure without blocking the view whilst also creating a more serene and inviting atmosphere surrounding the facility.

The accelerator itself is below ground, housed in a tunnel that sits within the landscape. Disguised beneath a berm of soil, a building known as the "klystron gallery" sits above the accelerator - only visible as a wall on one side, on the other the building blends into the Swedish landscape, appearing to be a meadow.  

Generating neutrons through a process called "spallation", the critical component of the BREEAM Outstanding-certified research campus is a 600m long proton accelerator that fires a high-energy proton beam at a target. When the protons hit the target, they cause the atoms to break apart, producing a shower of neutrons that are directed toward the instruments that allow scientists to study the properties of materials.  
 
The ESS research facility becomes a metaphor for the spallation process: a neutron sped through a linear accelerator – colliding with a tungsten core – scattering electrons into the landscape. The complex as a whole replicates this process through its layout generating a flexible, future-proof master plan – a landscaped proton accelerator, a circular target roof and scattered facility buildings intricately and delicately placed in the landscape.


European Spallation Source by Henning Larsen, Cobe and SLA. Photograph by Rasmus Hjorthøj.

A central point of orientation for the entire ESS campus is the circular roof above the target hall, home to one of the most important elements in the spallation process, the tungsten wheel. Taking inspiration from the wheel, the roof’s large, rounded structure appears to float above the hall – a lightweight construction ensures the roof carries its significant volume whilst also letting light into the hall and withstanding Sweden’s snowy climate.

To maintain a coherent design expression for the entire campus, the intention is that all buildings are monolithic land-art objects placed in the landscape. Each building at ESS varies in size and function, positioned in correlation with the spallation process; strategically, yet without a strict grid.  
 
Some volumes are solitary, and others are clustered, as it is imperative that the design also has the flexibility to accommodate new buildings in the future. The exterior reflects the purpose of each building, and the type and scale of the facades are based on a graduation scale from industrial to more refined. The buildings comprise of welcome and office spaces, auditoriums and laboratories, the accelerator building, a target room, and halls. Industrial facades indicate an interior housing the traveling particles, whereas more refined and shadow facades contain spaces for people to gather, exchange knowledge, and research.
 

European Spallation Source by Henning Larsen, Cobe and SLA. Photograph by Rasmus Hjorthøj.

The facility contains laboratories, and meeting halls in its main volume. The accelerator sits at the center of the development and becomes a physical and visual focal point that drives the activity and organization of the campus. The working and collaboration spaces in the research campus are designed to maximize the efficiency of information exchange, a learning environment of international caliber.

The European Spallation Source is currently under construction and the first experiments are expected to start in 2025/2026. The facility will be fully operational by 2027.