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How the Large Hadron Collider was built



Over the last 38 weeks we’ve highlighted some astonishingly complex machines and immense constructs that were built to a near impossible scale. But this puts them all to shame. Because no list of engineering feats from the last half-century would be complete without a look at the 27km long superconducting electromagnetic device buried 175m beneath the France-Switzerland border: The Large Hadron Collider. 

Heavily popularised, to the point of already being steeped in pop-culture mythology, the Large Hadron Collider (LHC) was built by the European Organisation for Nuclear Research (CERN) with the intention of conducting experiments that will help us better understand the building blocks of the universe. 111 nations provided design, construction, testing and software support in some form or another, making this one of the most internationally coordinated project ever undertaken.

The 27km long device collides particles at almost the speed of light, allowing CERN scientists to study the effects and learn more about the most basic elements of our universe and how they form the structure of the subatomic world. 

CERN scientist Chris Allton gave a brief analogy of how the machine works at the British Science Festival:

“Imagine investigating how a bicycle works: you can use spanners to take it apart.  But if you want to know how a proton works, nature hasn’t supplied any spanner small enough. The only option is to smash two protons together and look at what emerges. Imagine smashing together two bicycles and then trying to interpret the mess. more or less what the scientists at the LHC are trying to do.”

The device is immensely complicated with delicate instruments capable of detecting some of the smallest particles ever measured, built at a scale that could encircle an entire city. To do this took decades of work, with the initial plans put forth by groups at CERN as far back as the early 1980s, and finally approved in December 1994. 

It was constructed in a tunnel that was originally built between 1983 and 1988 for a similar device - the Large Electron-Positron Collider, which was dismantled in 2000. The 3.8m (12 feet) wide, concrete-lined tunnel runs underneath the Switzerland/France border with several smaller tunnels running up to surface buildings which house compressors, ventilation equipment, control electronics and refrigeration plants. It was built underground due to the cost benefits of excavating a tunnel as opposed to buying a complete ring of land and building on the surface. Doing so also reduces the impact on the landscape and means that the Earth’s crust can shield any excess radiation.

Building the tunnel had its own challenges. On average it lies 100m below the surface, due to geological considerations, but has a slight gradient of 1.4% (at its shallowest point near Lake Geneva the tunnel is just 50m below the surface - at its deepest under the Jura it is 175m). The slope was another cost measure - it minimised the length of some of the vertical shafts where it would be more difficult and costly to build them. 

The machine itself is not a perfect circle, instead it features eight arcs and eight “insertions”: straight sections with a transition region at each end. Each arc contains 154 dipole “bending” magnets, each measuring 15m in length, to channel the particle beams. An additional 392 quadrupole magnets, around 5-7m in length, are used to keep the beams focused. 

In total the device contains around 10,000 superconducting magnets made from copper-clad niobium-titanium, kept at an operating temperature of -271.25℃ by 96 tonnes of superfluid helium-4. These magnets direct and focus the beams and “squeeze” the particles in them together to increase chances of collision.

According to CERN, trying to make particles of this side collide is like firing two needs 10km apart with such precision that they meet halfway.

The machine was finally completed and began operations in 2008, while first collisions of particles were achieved in 2010. Operation of the LHC requires 200MW of electrical power from the French grid - approximately one third the energy consumption of the entire city of Geneva. In a day of operation it can generate around 140 terabytes of data. 

The total cost of building the LHC was approximately £3.74 billion, with the machine itself responsible for £3 billion of that (computers totalled £17 million while the experiments themselves run at around £728 million). Currently the LHC is undergoing upgrades for future experiments - a planned procedure that has been ongoing since the end of 2018. 

50 Years of Engineering

Through 2020 we’re celebrating Fircroft’s 50th anniversary by highlighting one incredible feat of engineering from each year, from 1970 to 2020. Read last week’s look back at the 2007 installation of the North Sea’s longest oil pipeline.

NES Fircroft supports engineers across the globe. Find your next engineering and technical job by registering your CV with us today.

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How the Large Hadron Collider was built - Time to read 5 min
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