Large Hadron Collider

Engineering places: CERN

Image credit: CERN

In a new series marking IET@150, we look at the greatest feats of engineering from around the world.

The great thing about engineering is that you can do it anywhere – on Mars, in Swindon, even in the bath. Arguably, the whole world is engineered. Yet every profession has its great sites, whose stories bring out the very best in us and so continue the tradition. Nowhere is this truer than in the series of under­ground bunkers straddling the Swiss-French border that are home to the European nuclear physics research centre CERN.

There are many paradoxes about CERN. First, it doesn’t exist any more. The Conseil Européen pour la Recherche Nucléaire was simply the body that set up this massive facility. As soon as the 12 founding countries signed up to the project, it became the European Organization for Nuclear Research, but EONR is harder to say, so CERN stuck.

The second paradox is what makes this a remarkable engineering site. Originally founded to study atomic and then subatomic interactions, as its interest has focused in on the ever smaller constituent parts of matter it has required ever larger machines to detect them. It has now detected what we believe to be the fundamental particles of the universe, and to do so has required the construction of the largest machine on Earth.

Then there are the people who work there. It’s a physics research facility, but physicists are a tiny minority, and CERN employs 10 times more engineers and technicians. It is in fact a monument to engineering.

CERN had relatively small beginnings, developing from the post-war realisation that many of the best scientists and engineers were headed to where there was still research funding, i.e., the USA. CERN was a direct attempt to stem this ‘brain drain’ and restore Europe’s position as a scientific powerhouse.

Neutral Switzerland was chosen to host the organisation, and ground was broken on the Meyrin site in May 1954. Three years later its first accelerator, the 600MeV, 15.7m-circumference Synchro­cyclotron was fired up, providing beams for experiments in particle and nuclear physics.

This was followed by a larger machine, designed to probe the internal workings of atoms. The Proton Synchrotron was the first circular accelerator at CERN, and briefly held the record for the highest-energy particle accelerator, at 24GeV. So began a long history of discoveries in particle physics, including the creation of the first antimatter, discovery of the W and Z bosons and, most recently, observation of the Higgs boson. These are great achievements in physics – but the engineering that made them possible touches all our lives.

It is hard to overestimate the problem-solving and sheer physical engineering that goes into building and running CERN’s machines. Just cutting tunnels for colliders has been one of civil engineering’s great successes. For the Super Proton Synchrotron (SPS), a perfect 7km-circumference circular tunnel was bored at an average depth of 40m beneath the Franco-Swiss border, and then equipped with 1,317 huge magnets. The job was finished in just four years.

That was child’s play compared to the next machine. The excavation of the 27km ring for the Large Electron-Positron Collider was the largest civil engineering project prior to construction of the Channel Tunnel, but despite its vast scale, the two ends came together with only 1cm of error.

Excavations are only the beginning of the challenges. Into these spaces go vast machines to accelerate and steer particles, and detectors that then measure the rubble created in their cataclysmic annihilation.

The Large Hadron Collider, the most powerful collider on Earth, operates in some of the most extreme environments in the universe. The particles are steered by 8.3-tesla fields created using 1,600 superconducting magnets chilled to -271.3°C (colder than outer space); this requires a complex liquid-helium plumbing system. The particles travel through an ultra-high vacuum also equivalent to that in space and are then concentrated at relativistic velocities and smashed into each other with a precision that CERN likens to “firing two needles 10km apart with such precision that they meet halfway”.

The four detectors are more impressive. The ATLAS detector sits in a 46×25×25-metre cavern 100m below ground, while the massive CMS, though smaller in volume, weighs in at 14,000 tonnes. ALICE can detect quark-gluon plasma like those found just after the Big Bang, with temperatures more than 100,000 times hotter than the centre of the Sun. Even the ‘baby’ of the four, the LHCb, is 20m long and comes in at 5,600 tonnes.

These dizzying statistics and mind-boggling costs might lead one to ask if it’s all worth it just to find the odd boson. Yet in setting the most complex set of engineering problems in history, CERN’s physicists have inspired the creation of technologies that affect us all today. So what have the CERN engineers done for us?

The list is impressive. First, there’s the capacitive touch screen, which is now ubiquitous on phones, computers and tablets. The first capacitive screen was suggested by CERN engineers struggling to work out how, with mid-1970s computers, mostly without mice, they could control the SPS. Then there’s CERN engineer Tim Berners-Lee’s solution to transferring data and messages between computers – the World Wide Web. The cryogenic expertise gained from superconducting magnets has also found its place in every hospital that has an MRI scanner.

These are just the headlines. That is without even considering the advances in electronics, hydraulics, safety equipment and procedures, programming and processing.

Yet CERN’s engineers face the same day-to-day problems as the rest of us. In April 2016, the LHC went into emergency shutdown after a 66kV transformer failed. The problem? A weasel had chewed through a wire. They still haven’t come up with a fool-proof solution to that one.

Timeline: CERN

December 1951: Unesco votes to establish a European Council for Nuclear Research. Two months later, 11 countries set up the CERN provisional council.

17 May 1954: Work begins on the Meyrin site in Switzerland.

11 May 1957: The 60 MeV Synchrocyclotron starts up.

24 November 1959: The Proton Synchrotron accelerates protons for the first time. It still operates by providing beams to larger machines.

1 September 1965: Dirac’s theory of matter/antimatter symmetry is confirmed.

17 January 1968: Georges Charpak’s ‘multiwire proportional chamber’ achieves a counting rate 1,000 times better than existing detectors.

27 January 1971: Protons are collided head-on in the Intersecting Storage Rings.

11 March 1972: Frank Beck suggests controlling the Super Proton Synchrotron (SPS) using capacitive touch screens.

4 April 1981: Proton-​antiproton collisions indicate that protons contain smaller constituents.

20 January 1983: The SPS discovers the Z and W bosons.

14 July 1989: Europe’s largest civil engineering project, the Large Electron-Positron collider, is switched on.

December 1990: Sir Tim Berners-Lee defines the Web’s basic concepts, html, http and URL, to aid information sharing.

15 September 1995: Antihydrogen is created in the Low-Energy Antiproton Ring.

20 November 2006: World’s largest superconducting magnet switches on.

September 2008: Days after the Large Hadron Collider starts up, a fault sees 53 magnets damaged.

5 June 2011: The ALPHA experiment traps antimatter atoms for 16 minutes, long enough to study them.

4 July 2012: ATLAS and CMS experiments observe a particle with properties matching the theoretically predicted Higgs boson.

1 July 2017: CERN confirms that the particle observed in 2012 is the Higgs boson.

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