Los Angeles Times

Big plans for upgraded collider

Giant proton-smasher goes back into action with a low-energy task but high hopes.

- By Amina Khan amina.khan@latimes.com

After a two-year hiatus, the giant proton-smasher that discovered the Higgs boson is back in action — and ready for bigger challenges.

Scientists at the Large Hadron Collider, the most powerful particle accelerato­r in the world, successful­ly sent two beams of particles in opposite directions around its 17-mile circumfere­nce Sunday.

Upgrades to the ringshaped collider, located near Geneva and operated by the European Organizati­on for Nuclear Research — known as CERN — will allow the beams to smash together at a nearly 60% higher energy level than before.

Scientists sent the first beam around the loop in one direction at 10:41 a.m. local time. They sent a second beam in the opposite direction about two hours later, at 12:27 p.m.

The beams were sent at relatively low energies, and the scientists will start to ramp up the energy levels in a few days after checking the machine’s systems. It will be several weeks to a couple of months before the scientists start colliding particles, officials said.

“Today, CERN’s heart beats once more to the rhythm of the LHC,” Rolf-Dieter Heuer, CERN’s director-general, said in a statement.

The new and improved Large Hadron Collider was shut down over the last two years to undergo a host of upgrades, including replacing worn-out magnets and outfitting 10,000 electrical interconne­ctions with metal splices that will help divert electrical current in case of a fault.

At maximum energy, each beam will deliver energies of 6.5 trillion electron volts, for a particle-smashing total of up to 13 trillion electron volts, compared with its previous energy limit of 8 trillion electron volts.

By examining the showers of particles released when the proton beams smash together, scientists were able to find evidence of the Higgs boson, a mysterious particle that had been long theorized but never detected. The discovery earned the physicists who predicted the particle’s existence a Nobel Prize in 2013.

The higher energies that the Large Hadron Collider will now be able to reach will allow researcher­s to explore mysterious phenomena that the current understand­ing of physics cannot explain.

Among the questions it hopes to answer: what dark matter — that strange stuff that accounts for most of the matter in the cosmos — is made of and what happened to all of the antimatter in the universe.

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