The Large Hadron Collider has restarted after a three-year revamp, with experts hoping the biggest research machine ever built will now go even faster in a bid to unspin the secrets of the universe.
Two proton beams were pushed through the collider's 27-kilometre tunnel on Friday for the first time since December 2018 and circulated as planned in opposite directions, Joachim Mnich, director of research at the European Organisation for Nuclear Research (CERN), said.
He could only follow events under the French-Swiss border from home because of a coronavirus infection.
"That's why there is no champagne at my place," the German told DPA.
"But I'm sure it was different in the control room of the particle accelerator."
It takes six to eight weeks for the LHC to reach full speed and only then can proton collisions take place again.
The collider accelerates subatomic particles to nearly the speed of light and smashes them together with the aim of clarifying the theory of the Big Bang, believed to be the moment the universe sprang to life 14 billion years ago.
In 2012, the collider showed that the mysterious Higgs boson particle is likely to exist.
The particle is believed to be responsible for all mass in the universe.
The Higgs boson, nicknamed the "God particle," was the missing piece in the standard model of physics which describes how nature's smallest building blocks interact but could not previously explain why they have mass.
The three-year maintenance means the collider is now expected to run smoothly for the next four years.
"By the end of 2025, we hope to double the number of collisions since the particle accelerator went into operation," Mnich said.
The accelerator has already had two phases of operation: from 2009 to 2012 and from 2015 to 2018.
Mnich said about 1,000,000,000,000,000 - a quadrillion - collisions should be possible each year.
But only one in perhaps 100,000 collisions brings to light processes worthy of closer analysis.
The data is stored within milliseconds but the analysis often takes years.
This was the case at the US particle physics research centre Fermilab, which came up with a sensation at the beginning of April.
Physicists there recalculated the W boson, which transmits one of the four fundamental forces that determine the behaviour of matter in the universe.
The researchers determined with high precision that it is heavier than the standard model of particle physics predicts.
"We can only congratulate our colleagues at Fermilab," Mnich said.
The W boson had been discovered at CERN in 1983.
He expects the US measurements will be confirmed or rejected at CERN in the next four years.
"If the result is true, this could be an indication of an unknown force of nature, or an indication of additional particles that we don't know about yet," he said.
© DPA 2022