The thing

Antwerp pedestrian tunnel converted to particle accelerator

5 min
Text Arkasha Keysers
Image CERN

Underground at CERN, close to Geneva, sits the largest particle accelerator in the world. To introduce future students and passers-by to the wonderful world of elementary particle physics, the University of Antwerp converts the Antwerp pedestrian tunnel to a particle accelerator. Drop by from 13 until 24 February to make the particles collide yourself.


‘I’ve been using the pedestrian tunnel all my life, because my parents live on the Left Bank,’ says elementary particle physicist Maja Verstraeten. ‘When I cycle through it, I always think of CERN’s Large Hadron Collider (LHC), and picture myself as a proton rushing along inside.’


The LHC is the largest particle accelerator in the world. Since 2008, protons (particles of atom nuclei) are sent through this circular, 27-kilometre-long underground tunnel near Geneva. When the protons approach the speed of light, they collide with an energy equal to the big bang. In the resulting wreckage, scientists hope to find traces of ‘primordial particles’ that tell us more about the origins of our universe and the composition of matter. ‘Wouldn’t it be fun to deck out the pedestrian tunnel as a particle accelerator?’ Verstraeten thought during one of her bike rides.

She brought her idea to the Agency for Roads and Traffic. ‘From the very start, all of those people contributed constructive thoughts about what the tunnel should look like,’ she says referring to the cooperative process. After this, she spoke to the University of Antwerp, where she was doing a PhD. She knew the university had an important collaboration with CERN.


Building the detector


‘In Belgium, there are around a hundred people who run experiments with the LHC,’ says elementary particle physicist Pierre Van Mechelen (Faculty of Science). ‘At UAntwerp we built parts of the Compact Muon Solenoid (CMS), a large detector used for analysing traces. We are currently also involved in constructing its upgrade and run a lot of analyses with the collected data. We actually also collaborated on the discovery of the Higgs particle.’

Nobel Prize for Physics


There, he said it. As early as 1964, the Higgs particle was predicted by the Belgian Robert Brout and François Englert and the British Peter Higgs to make what is known as the Standard Model of elementary physics work. The particle gives other elementary particles their mass. The fragment has a mass that’s over 125 larger than that of the proton. Which also supports Einstein’s theory of relativity, asserting that mass and energy are interchangeable.

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When I cycle through the pedestrian tunnel, I always think of CERN’s Large Hadron Collider (LHC), and picture myself as a proton rushing along inside.

Maja Verstraeten

Even though the theory of the Higgs particle had been around for a while, the particle was only observed with the particle accelerator in 2012. This resulted in François Englert and his British colleague being presented with the Nobel Prize for Physics in 2013. Englert’s Belgian colleague and mentor Robert Brout had already passed away by then.


Fundamental research with practical applications


‘To this day, Belgian physicists continue to have a good reputation,’ says Van Mechelen. ‘About twenty UAntwerp colleagues work on particle physics. Our research is fundamental and theoretical in nature. We are interested in knowing how the universe works, not in practical applications, although that doesn’t mean there are no practical applications.’


The CERN experiments demand so much from technology that that technology can subsequently be applied in other areas, ‘such as superconductivity, isotopes for medical applications, and using artificial intelligence to analyse big data,’ says Van Mechelen. Another notable example is the invention of the world wide web, which was developed at CERN to enable scientists to communicate to one another.

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Belgian physicists continue to have a good reputation. Our research is fundamental and theoretical in nature. 

Pierre Van Mechelen

Propelled forward


CERN is a high-tech, stimulating and motivating environment. Scientists and engineers acquire skills there that will benefit them throughout their careers. ‘Although CERN’s goal is fundamental and theoretical, it’s also a fantastic training ground for people from all over the world,’ says Van Mechelen. Verstraeten agrees: ‘How you share information and work together is the most important aspect of science, even though that wasn’t clear to me yet when I started studying. When I was eighteen, I had read books by Newton, Hawking and Einstein, and dreamt of making such a big discovery myself. At the same time, I thought competition would be fierce. Turns out the opposite is true. You’re only as strong as your team, everyone propels each other forward. I hope that this insight provides peace of mind and enthusiasm to those starting out with their studies.’

The particle accelerator in the Antwerp pedestrian tunnel is a collaboration between the University of Antwerp and the Agency for Roads and Traffic. From 13 until 23 February, you can make the protons collide in this spectacular light and sound installation. More info (in Dutch) at


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