STAR Experiment Detects Quark-Gluon Plasma in Oxygen Collisions at Brookhaven's RHIC

Key facts

• On 30 October 2026, scientists with the STAR experiment at the Relativistic Heavy Ion Collider (RHIC), Brookhaven National Laboratory, Upton, New York, announced evidence of quark-gluon plasma (QGP) production in oxygen-nucleus collisions.
• The analysis used oxygen-oxygen collision data recorded at RHIC in 2021 at 200 billion electron volts (GeV), and researchers observed about 20% suppression of high-energy particles attributed to jet quenching.
• The findings were published in Physical Review Letters and establish a lower-energy boundary for producing QGP in this small collision system; earlier evidence came from heavier-nucleus collisions or oxygen collisions at the Large Hadron Collider (LHC), where energies exceed 5,000 GeV.
• Li Yi of Shandong University oversaw the analysis, and STAR physicist Rongrong Ma discussed the value of studying smaller collisions.
• RHIC, a US Department of Energy Office of Science User Facility, operated from 2000 until its final run, and its STAR and sPHENIX detectors recorded oxygen-oxygen collisions on 6 February 2026.
• In quark-gluon plasma, quarks are deconfined unlike in ordinary matter, and partons lose energy mainly through medium-induced gluon radiation, with experiments directly observing hadrons rather than the original partons.