CERN scientists create quark-gluon plasma with lightest nuclei ever

Physicists working at CERN have demonstrated that quark-gluon plasma — the primordial state of matter that filled the universe during its first millionth of a second — can be produced by smashing together nuclei far lighter than previously thought possible. The results, published in Physical Review Letters as an Editors' Suggestion, also revealed that the geometric shapes of atomic nuclei leave a measurable imprint on the collision debris, offering a new window into nuclear structure.miragenews+1

Smaller Nuclei, Same Extreme Matter

The research, led by Associate Professor You Zhou of the Niels Bohr Institute at the University of Copenhagen, was conducted within the international ALICE collaboration at the Large Hadron Collider. For decades, producing quark-gluon plasma required collisions of heavy nuclei such as lead. The new experiments used oxygen-16 and neon-20 — nuclei with roughly one-tenth the mass of lead — accelerated to near light speed.home+1

"We have pushed the boundary for how small the atomic nuclei can be while still recreating this primordial matter," Zhou said. "We now know more about the fundamental conditions required for matter to transition into this extreme state."miragenews

The oxygen and neon collisions took place at the LHC between late June and early July 2025. Over the following year, all four major LHC experiments — ALICE, ATLAS, CMS and LHCb — independently reported signs of quark-gluon plasma formation in these lighter collision systems.cerncourier+2

Bowling Pins and Shadows

Beyond confirming plasma creation, the experiment yielded an unexpected bonus: the movement patterns of particles emerging from the collisions encode the shape of the colliding nuclei. Oxygen-16, which is roughly spherical, produces a rounded particle flow pattern. Neon-20, predicted to be elongated, produces a distinctive bowling-pin-shaped signature.alice-collaboration.cern+2

"It is a bit like shining light on an object and seeing its shadow," said postdoctoral researcher Emil Gorm Dahlbæk Nielsen, a co-author. "The movement of the particles reveals the geometric shape of the atomic nuclei that was present at the beginning of the collision."miragenews

A New Tool for Nuclear Physics

The researchers describe the approach as a potential paradigm shift. Nuclear shapes have traditionally been studied at low energies through rotational and vibrational properties. The new method instead reads nuclear geometry from the debris of ultrarelativistic collisions — linking two seemingly distant fields of physics.alice-collaboration.cern+1

The next step is to test even lighter nuclei such as helium-4 to determine the minimum conditions under which quark-gluon plasma can form. "What is fascinating is that we can use the same experiment both to learn about the structure of atomic nuclei and to gain a better understanding of what happened during the birth of the Universe," Zhou said.miragenews