How CERN’s Location Was Chosen to Unite Europe
Exploring the physics behind the Large Hadron Collider and the factors that led to Geneva being chosen as its home
I could only write so many posts about world-leading experiments without mentioning the Large Hadron Collider (LHC). I was lucky enough to see the experiment whilst visiting the European Organisation for Nuclear Research (CERN) in 2014, and I was so impressed by the experiment and the scientists working there that it was a huge factor in my decision to apply to study physics at university.
The LHC is the largest and most powerful particle accelerator in the world and is located in a tunnel with a circumference of 27 km. Two high-energy beams consisting of hadrons travel in opposite directions inside the accelerator, before being made to collide. Hadrons are particles (usually protons in this case) that are made up of quarks, which are a type of elementary particle. The beams are guided around the ring by a magnetic field produced by superconducting magnets. The superconducting state of the magnets allows high currents to flow without a loss of energy due to electrical resistance, and can be achieved by cooling the magnets to -271.3 ºC using liquid helium.
The beams travel at a speed only 6.2 mph (roughly jogging speed) slower than the speed of light, and are made to collide at four locations around the ring within one of the four detectors (ATLAS, CMS, ALICE, and LHCb), which are each designed for a specific type of research. With these detectors, scientists can search for particles produced in collisions, which would not be observable at lower impact energies.
The most well-known success story of the LHC occurred in 2012, when the existence of the Higgs boson, the particle that had been theorised to give mass to elementary particles, was confirmed by the ATLAS and CMS collaborations. As a result, Peter Higgs and François Englert received the Nobel Prize in Physics for their predictions.
High-energy particle physics experiments aim to answer some fundamental questions involving the interactions and forces between particles. The results of particle collisions at the LHC could also allow us to explore the validity of the Standard Model of particle physics, which describes three of the fundamental forces and all of the known elementary particles. Observing new physics at high energies would show us the ways in which the Standard Model is unsatisfactory.
My first post was about detecting dark matter using the method of direct detection at SuperCDMS. It is worth mentioning that the LHC is also involved in the search for dark matter, but here the aim is to produce dark matter particles by colliding proton beams and detecting WIMPs indirectly due to the missing energy and momentum that goes undetected in the collision.
The LHC is located beneath the French-Swiss border near Geneva. This site was chosen for CERN for several reasons. At the end of the Second World War, several scientists envisioned a physics laboratory that would unite European scientists and combat the “brain drain” due to scientists leaving post-war Europe for North America. In 1952, Geneva was selected as the location for the CERN laboratory over proposals from the French, Dutch and Danish governments.
Geneva’s location in the centre of Europe was a factor in this decision, as was Swiss neutrality in the war, the importance of which is conveyed through CERN’s convention, which states: “The Organization shall have no concern with work for military requirements and the results of its experimental and theoretical work shall be published or otherwise made generally available.”
After being founded by 12 member states in 1954, CERN now runs the world’s largest particle physics laboratory. There are currently 23 member states, with Israel being the first non-European full member. Between them, the members are contributing a total equivalent to 1,046 million euros to CERN in 2019.
This demonstrates how the choice of location for an experiment can be political, as well as practical, in order to send a strong message of unity and peace.
