Large Hadron Collider particle accelerator up and running after three-year shutdown

The world’s most powerful particle accelerator – the Large Hadron Collider (LHC) – has sprung back to life after a three-year shutdown.

After planned maintenance and upgrades, it has been turned back on and will shortly start another run of cutting-edge physics experiments.

The LHC, at Cern, on the French/Swiss border near Geneva, was switched off in 2018 to let scientists and engineers from around the world make it even more powerful.

Yesterday, particles were pushed through the collider’s 27km ring for the first time since December 2018.

However, it will take six to eight weeks for the LHC to get up to full speed, at which point proton collisions can take place again.

Head of Cern Beams department, Rhodri Jones, said: “These beams circulated at injection energy and contained a relatively small number of protons.

“High-intensity, high-energy collisions are a couple of months away.

“But first beams represent the successful restart of the accelerator after all the hard work of the long shutdown.”

While pilot beams circulated in the LHC for a short time in October 2021, the beams that circulated yesterday mark not only the end of the second long shutdown for the LHC, but also the beginning of preparations for four years of physics data taking, which is expected to start this summer.

This third run of the LHC, called Run 3, will see the machine’s experiments collecting data from collisions not only at a record energy but also in unparalleled numbers.

The Atlas and CMS experiments can each expect to receive more collisions during this physics run than in the two previous physics runs combined, while LHCb, which underwent a complete revamp during the shutdown, can hope to see its collision count increase by a factor of three.

The unprecedented number of collisions will allow international teams of physicists at Cern and across the world to study the Higgs boson in great detail and put the standard model of particle physics to the most stringent tests yet.