Large Hadron Collider returns after three years to push physics to the limit

22 Apr 2022

The LHC tunnel at point 1. Image: CERN

The upgraded particle accelerator is expected to investigate new theories in particle physics, including the possible existence of a fifth force of nature.

After more than three years offline for maintenance and upgrades, the world’s largest and most powerful particle accelerator has restarted today (22 April) and will begin investigating theories that could change our understanding of physics.

At around 11am IST, two beams of protons circulated in opposite directions around the Large Hadron Collider’s (LHC) 27km ring. The collider is run by CERN, the European organisation for nuclear research, which is based near Geneva in Switzerland.

“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,” Rhodri Jones, head of the beams department at CERN, said. “But first beams represent the successful restart of the accelerator after all the hard work of the long shutdown.”

The return of the particle accelerator could lead to some exciting developments in physics. In 2012, scientists used the LHC to discover the long-predicted Higgs boson, also known as the ‘God particle’.

Over the last three years, CERN has been working to upgrade its machines and facilities to take more precise measurements than ever.

CERN director for accelerators and technology Mike Lamont said: “The LHC itself has undergone an extensive consolidation programme and will now operate at an even higher energy and, thanks to major improvements in the injector complex, it will deliver significantly more data to the upgraded LHC experiments.”

According to CERN, two upcoming experiments should each receive more collisions during this third run of the LHC than in the two previous physics runs combined.

ALICE, a specialised detector for studying heavy-ion collisions, is expected to record 50 times more collisions after its major upgrade, while the LHCb experiment should see its collision count increase by a factor of three.

CERN scientists believe the immense number of expected collisions will let them study the Higgs boson in greater detail than ever before, putting the standard model of particle physics to the test.

The LHC has a lot of exciting new theories to investigate that have emerged since it went offline for upgrades. A study measuring the mass of the W boson published earlier this month has scientists questioning the foundations of the standard model. In this study, scientists found the W boson to be significantly heavier than expected.

Last year, new evidence from Fermilab also suggested that tiny subatomic particles called muons could break the known laws of physics, hinting at the existence of a fifth force of nature.

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Leigh Mc Gowran is a journalist with Silicon Republic