The world’s largest particle accelerator, the Large Hadron Collider, is back in action after a three-year hiatus for maintenance and an upgrade with more energy, higher intensity, and greater precision beams.
The LHC at CERN, outside Geneva, is back in action, this time running 24/7 with a record energy of 13.6 trillion electron volts. The upgrades should give LHC tools more precision and allow for more particle collisions, brighter light and more discoveries about particles in quantum field theory.
CERN used the LHC to Higgs boson on July 4, 2012, before the first long shutdown. At the time, under LHC “Run 1”, the LHC operated on 3.5 trillion electron volts (TeVs). Run 2 took place between 2015 and 2018 with proton beams colliding 13 TeVs before the second long shutdown. Now it’s time for Run 3 at 13.6 TeV or 6.8 TeV per beam.
Rende Steerenberg, Head of the Operations Group of the LHC Beams Department, said that with 6.8 TeV for Run 3 it wants to boost LHC to “140 billion parts per package or per bunch.” From 2023, it wants to increase this to 180 billion parts per package. “Of course, this will give us many, many more collisions in the experiments.”
An electron volt is a measure of the kinetic energy obtained by an electron accelerating from rest. Hence the need for accelerator like LHC with a circumference of 27 km, which accelerates hadron particles (such as lead, xenon and oxygen ions at different levels of the mass spectrum) in a way that forms two beams traveling in opposite directions, almost at the speed of light. Inside the machine, the beams collide with four points or “detectors” called ATLAS, CMS, ALICE and LGCb, each of which aims to measure different types of hadron particles.
It’s the Higgs boson (or wave in quantum field theory) that is thought to give mass to the particles that form the basis of stars, planets and everything else. When two electrons interact, they exchange, for example, light particles or photons that are the ‘force carriers’ of an electromagnetic interaction, CERN explains.
The updated LHC will be able to create “stable beams,” a state that allows scientists to turn on all their subsystems for experiments and begin collecting data.
“We will focus the proton beams at the interaction points to a beam size of less than 10 microns, to increase the collision speed,” said Mike Lamont, director of accelerators and technology at CERN.
“Compared to Run 1, in which the Higgs was discovered with 12 inverse femtobarns, we now deliver 280 inverse femtobarns1 in Run 3. This is a significant increase, paving the way for new discoveries.”
The LHCb experiment has undergone a complete overhaul and seems to increase the data recording speed by a factor of ten, while ALICE aims for a 50-fold increase in the number of registered collisions.
Scientists hope to answer questions about the origin of the asymmetry between matter and antimatter in the universe and look for dark matter candidates.
“We look forward to measurements of the decay of the Higgs boson to second-generation particles, such as muons. This would be an entirely new result in the Higgs boson saga, confirming for the first time that particles of the second generation also gain mass through the Higgs mechanism,” said CERN theorist Michelangelo Mangano in a press release†