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How FAIR is being built

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The existing GSI facility (left) and the new FAIR complex (right, with lake and large accelerator ring in the forest; photo montage: ion42 for FAIR)

The FAIR international particle accelerator is set to be one of the largest research facilities in the world. Based in the German city of Darmstadt (in the state of Hesse), the complex will cover an area of 20 hectares and require 600,000 cubic metres of concrete as well as 65,000 tons of steel. Construction teams will be building a tunnel to house the heart of the complex, a ring accelerator with a circumference of 1.1 kilometres. The 24 buildings and tunnel sections provide 62,000 square metres of usable space and sufficient room for a total of 3.5 kilometres of beam control tubes as well as huge detectors and a complex technical infrastructure.

The sensitive, sophisticated technology to be housed at FAIR poses a challenge to construction teams. FAIR will be used to measure tiny particles – atomic nuclei and the particles they are made up of – with the utmost accuracy. To do this, the atomic nuclei will be accelerated to extremely high speeds, enabling them to travel more than 270,000 times a second around the large accelerator ring.

Nearing light speed

FAIR will be built to the east of the GSI facility. The existing accelerators at GSI will be used as pre-accelerators. The architecture of the new facility aligns with the beam path and the experiments, all of which are designed to very compact specifications. Radiation protection and cost optimisation were also key planning criteria. The large accelerator ring will be installed in a tunnel at a depth of up to 17 metres below ground. This tunnel will be built through open pits. The remaining buildings will be situated to the south of the accelerator tunnel. As this project entails clearing around 20 hectares of woodland, it is being accompanied by extensive environmental measures to compensate for loss of habitat in line with legal regulations. Some of these measures were already implemented before clearance started.

The construction project is split into several modules. The first module concentrates on constructing the large accelerator ring (SIS 100) along with two smaller accelerator and storage rings, as well as a linear accelerator for protons (p-Linac). Another large accelerator ring, SIS 300, will be installed in the tunnel at a later stage. Space has also been allocated on the site for three further experimental and storage rings, also to be installed at a later date.

Construction and design are divided into the following organisational units:


Accelerators (“the machine”)

Scientific experiments and detectors


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