The Large Hadron Collider's ALICE detector is optimized to record data from collisions of heavy ions such as lead. (Mona Schweizer/CERN)

The world's largest high-energy particle collider has recreated conditions similar to an early phase of the Big Bang.

The extreme heat, thousands of times hotter than the centre of the sun, was the result of the Large Hadron Collider's first collisions of heavy particles called lead ions.

The collisions were recorded shortly after midnight CET Sunday, reported CERN, the European organization for nuclear research that runs the underground collider near Geneva, Switzerland, in a news release Monday.

Previously, the facility had only collided much smaller particles called protons.

Researchers hope the collisions of lead ions, each of which contains 82 protons, produce a new phase of matter called a quark-gluon plasma, CERN said in a statement. The researchers want to study how that quark-gluon plasma evolved into the kind of matter that makes up the universe today

Quarks and gluons are very tiny particles that combine into larger particles called protons. Those in turn combine with electrons to form atoms in the world we know today. However, during the initial moments of the Big Bang, that hadn't yet happened.

Millionth of a second after Big Bang

"One millionth of a second or a few hundred millionths of a second after the Big Bang, the universe was probably in this state where all the quarks were free," said Pierre Savard, a University of Toronto particle physicist and a scientist at Vancouver's TRIUMF laboratory. He is involved in studies at the Large Hadron Collider.

At that point, the temperature was likely 100,000 to a million times that at the centre of the sun.

Physicists hypothesize that as the universe cooled, small groups of quarks separated into individual protons, and as it cooled further, small groups of protons combined with electrons to form individual atoms.

CERN has claimed to have produced a quark-gluon plasma before, using a different particle collider, Savard said. But such an event is difficult to verify through computer models that reconstruct the collision because of the huge number of tiny particles involved, he added.

Compared to other colliders, the LHC has a much better chance of producing a quark-gluon plasma because of the extremely high energies it operates at — "well above" what is needed, said Savard.

However, it will probably still be a while before the LHC researchers figure out whether they have, in fact, created a quark-gluon plasma, Savard said. "It's likely, but we'll need quite a bit of data and analysis."

The collider will continue smashing lead ions together until Dec. 6.

It will re-start with proton collisions in February.

Savard's own research, which is part of an experiment called ATLAS, involves proton collisions. They are simpler to study because they involve fewer particles.