CERN

The Large Hadron Collider Is About to Ramp Up to Unprecedented Energy Levels

Ten years after it discovered the Higgs boson, the Large Hadron Collider is about to start smashing protons together at unprecedented energy levels in its quest to reveal more secrets about how the universe works.

The world's largest and most powerful particle collider started back up in April after a three-year break for upgrades in preparation for its third run. 

From Tuesday it will run around the clock for nearly four years at a record energy of 13.6 trillion electronvolts, the European Organisation for Nuclear Research (CERN) announced at a press briefing last week. 

It will send two beams of protons – particles in the nucleus of an atom – in opposite directions at nearly the speed of light around a 27-kilometre (17-mile) ring buried 100 meters under the Swiss-French border.

The resulting collisions will be recorded and analyzed by thousands of scientists as part of a raft of experiments, including ATLAS, CMS, ALICE and LHCb, which will use the enhanced power to probe dark matter, dark energy and other fundamental mysteries.

1.6 billion collisions a second

"We aim to be delivering 1.6 billion proton-proton collisions per second" for the ATLAS and CMS experiments, CERN's head of accelerators and technology Mike Lamont said.

This time around the proton beams will be narrowed to less than 10 microns – a human hair is around 70 microns thick – to increase the collision rate, he added.

The new energy rate will allow them to further investigate the Higgs boson, which the Large Hadron Collider first observed on 4 July 2012.

The discovery revolutionized physics in part because the boson fit within the Standard Model – the mainstream theory of all the fundamental particles that make up matter and the forces that govern them.

However several recent findings have raised questions about the Standard Model, and the newly upgraded collider will look at the Higgs boson in more depth.

"The Higgs boson is related to some of the most profound open questions in fundamental physics today," said CERN director-general Fabiola Gianotti, who first announced the boson's discovery a decade ago.

Compared to the collider's first run that discovered the boson, this time around there will be 20 times more collisions.

"This is a significant increase, paving the way for new discoveries," Lamont said.

Joachim Mnich, CERN's head of research and computing, said there was still much more to learn about the boson.

"Is the Higgs boson really a fundamental particle or is it a composite?" he asked.

"Is it the only Higgs-like particle that exists – or are there others?"

'New physics season'

Past experiments have determined the mass of the Higgs boson, as well as more than 60 composite particles predicted by the Standard Model, such as the tetraquark.

But Gian Giudice, head of CERN's theoretical physics department, said observing particles is only part of the job.

"Particle physics does not simply want to understand the how – our goal is to understand the why," he said.

Among the Large Hadron Collider's nine experiments is ALICE, which probes the matter that existed in the first 10 microseconds after the Big Bang, and LHCf, which uses the collisions to simulate cosmic rays.

After this run, the collider will come back in 2029 as the High-Luminosity LHC, increasing the number of detectable events by a factor of 10.

Beyond that, the scientists are planning a Future Circular Collider – a 100-kilometre ring that aims to reach energies of a whopping 100 trillion electronvolts.

But for now, physicists are keenly awaiting results from the Large Hadron Collider's third run.

"A new physics season is starting," CERN said.

Ten years ago, scientists were able to discover the Higgs Boson particle and help make sense of the our universe using the Large Hadron Collider. They did it again in 2018, unlocking new insights on protons.

Now, with a new host of questions, they plan to restart the particle accelerator this month to possibly better understand cosmic unknowns like dark matter.

"This is a particle that has answered some questions for us and given many others," Dr. Sarah Demers, a physics professor at Yale University, tells NPR.

The Higgs Boson particle was first observed when scientists at the European Center for Nuclear Research, or CERN, spun and crashed particles together near the speed of light. They did that by using the world's largest and most powerful particle accelerator — the Large Hadron Collider.

Since 1964, physicists theorized this particle existed, but it took nearly 50 years to find evidence.

Scientists believe the Higgs field was formed a tenth of a billionth of a second after the Big Bang and without it, stars, planets and life would not have emerged.

The evidence of the Higgs Boson's existence was a major milestone in fundamental physics, and Dr. François Englert and Dr. Peter Higgs won a Nobel Prize in physics. Despite the scientific achievement, the work in understanding how the universe operates is far from over.

The collider finished a second experimental run in 2018 that gave new insights into the structures of protons and how the Higgs Boson decays.

And after more than three years of maintenance and upgrades, the collider will launch again on Tuesday – this time tripling the data, maintaining intense beams for longer and generally enabling more studies.

"There has to be more out there because we can't explain so many of the things that are around us," said Demers, who is also at CERN working on the third run. "There's something really big missing, and by really big, we're talking about 96 percent of the universe really big."

What Demers is referring to is dark matter, which is invisible matter believed to exist from observations of the cosmos, and dark energy, which fuels the accelerating expansion of the universe. She hopes that the upcoming run will produce insight into the elusive but overwhelming bulk of our cosmos.

In a news release, CERN wrote, "Finding the answers to these and other intriguing questions will not only further our understanding of the universe at the smallest scales but may also help unlock some of the biggest mysteries of the universe as a whole, such as how it came to be the way it is and what its ultimate fate might be."

The third run is expected to go on for the next four years, and scientists are already starting to work on Run 4, scheduled to begin in 2030.