AFP, published on Friday, April 22, 2022 at 5:40 p.m.
CERN’s LHC, the world’s largest and most powerful particle accelerator located near Geneva, restarted on Friday following more than three years of work to increase its power and thus pave the way for new physics.
This Friday around 12 p.m., “two beams of protons (particles from the nucleus of the atom, editor’s note) circulated in opposite directions along the 27-kilometer ring” of the Large Hadron Collider (LHC), announced CERN ( European Organization for Nuclear Research) in a press release.
Buried 100 meters underground on the Franco-Swiss border, the gigantic ring had been in technical stoppage since December 2018 for maintenance and improvement work, in the second longest break in its history. The experiments at the LHC, started in 2008, notably led to the revolutionary discovery of the Higgs boson, the keystone of the fundamental structure of matter.
The recovery will take place gradually: a small number of protons have circulated for the moment in the two beams, at 450 billion electron volts (450 gigaelectron volts – GeV), a low collision rate but which will increase in power.
“The high-intensity, high-energy collisions will occur in a few months,” said Rhodri Jones, head of CERN’s beams department, welcoming a “successful” restart.
The principle of the collider, made up of thousands of superconducting magnets, is to cause particles to collide at colossal speeds to generate elementary particles, which are infinitely small.
As the machine returns to service, the teams will increase the energy and intensity of the beams, to conduct collision experiments with a record energy of 13.6 trillion electronvolts (13.6 teraelectronvolts – TeV).
This will allow the four main LHC detectors (ALICE, ATLAS, CMS and LHCb) to receive more particle collisions and therefore to read a much larger mass of data.
CERN physicists will be able to “study the Higgs boson in great detail” and further test the Standard Model of particle physics, recently shaken by several experiments.
Like elementary particles like the W boson or the bottom quark which, during experiments with the LHCb detector “does not behave as expected” by this model, recalls physicist Harry Cliff, from the University of Cambridge.
“All these anomalies might be explained by a new force” which would be added to the four fundamental forces governing the Universe (strong, weak, gravitational and electromagnetic), explained the scientist to AFP.
One of the biggest shortcomings of the Standard Model is its inability to detect dark matter, an invisible and hypothetical mass populating the Universe.
Among the hopes of the more than 12,200 scientific users of CERN, that of highlighting the supersymmetrical particles, which might convey dark matter. “The coming years promise to be very exciting” at the LHC, according to Harry Cliff.
