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Large Hadron Collider restarted in hunt for dark matter, antimatter, more

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World’s biggest and most powerful particle accelerator – the Large Hadron Collider (LHC) – has been re-started as expected following a two year shut down meant for upgrades, maintenance and further fine-tuning. The amped-up LHC will run at double the power when operational at full capacity.

“Operating accelerators for the benefit of the physics community is what CERN’s here for,” said CERN Director-General Rolf Heuer in a press release. “Today, CERN’s heart beats once more to the rhythm of the LHC.”

The restart of the LHC saw protons making their way around its 27-kilometre tunnel for the first time since 2013. Though the proton beams have started travelling in opposite directions in parallel pipes actual collisions will not begin for at least another month. But when they do happen, they will take place with nearly double the energy the LHC reached during its first run.

The beams have arrived a week or so later than originally scheduled, due to a now-resolved electrical fault.

The protons are injected at a relatively low energy to begin with. However, engineers hope to gradually increase the beams’ energy to 13 trillion electronvolts, double what it was during the LHC’s first operating run.

“After two years of effort, the LHC is in great shape,” said CERN Director for Accelerators and Technology, Frédérick Bordry. “But the most important step is still to come when we increase the energy of the beams to new record levels.”

Scientists hope to glimpse a “new physics” beyond the Standard Model of particle physics. The Brout-Englert-Higgs mechanism, dark matter, antimatter and quark-gluon plasma are all on the menu for LHC season 2.

After the discovery of the Higgs boson in 2012 by the ATLAS and CMS collaborations, physicists will be putting the Standard Model of particle physics to its most stringent test yet, searching for new physics beyond this well-established theory describing particles and their interactions.

The model describes 17 subatomic particles, including 12 building blocks of matter and 5 “force carriers” – the last of which, the Higgs boson, was detected by the LHC in 2012.

Things beyond the Standard Model have been proposed to explain several baffling properties of the universe, but never directly detected.

These include dark energy and dark matter. Dark energy is the all-pervading force suggested to account for the universe expanding faster and faster.

Dark matter is the “web” that holds all visible matter in place, and would explain why galaxies spin much faster than they should, based on what we can see.

By taking matter to states we have never observed before, physicists hope to find something unexpected that addresses some of these questions.

Debris from the tiny but history-making smash-ups might contain new particles, or tell-tale gaps betraying the presence of dark matter or even hidden dimensions.

“The return of beams to the LHC rewards a lot of intense, hard work from many teams of people,” said Head of CERN’s Beam Department, Paul Collier. “It’s very satisfying for our operators to be back in the driver’s seat, with what’s effectively a new accelerator to bring on-stream, carefully, step by step.”