Relativistic Heavy Ion Collider ends as U.S. particle physics looks ahead.

The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory completed its 25-year run with a final set of collisions, and the lab plans to reuse part of RHIC's infrastructure to build an Electron-Ion Collider over the next decade.

The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has concluded its quarter-century of operations. Scientists and officials gathered in a control room as the final collisions were made and a DOE official pressed a red button to mark the end of the collider's run. RHIC was built to recreate the quark-gluon plasma of the early universe and to probe the strong force inside protons. The laboratory plans to replace part of the RHIC rings with infrastructure for a new Electron-Ion Collider (EIC) that is slated for construction over the next decade. Key facts: - RHIC operated for about 25 years and used two 2.4-mile-wide storage rings to collide heavy ions and polarized protons. - The final run ended in a public event at Brookhaven, where Darío Gil, the DOE Under Secretary for Science, pressed the button to stop the collider's collisions. - RHIC produced and studied quark-gluon plasma, which behaved like an almost frictionless liquid and revealed high vorticity. - In 2023 RHIC data moved scientists closer to resolving the proton spin question by accounting for quark and gluon spin contributions, while some spin remains attributed to their motion. - The sPHENIX detector produced most of the hundreds of petabytes of data gathered in the last run, and analysis of that data is expected to continue producing results, including reported direct evidence of virtual particles in the plasma. - Plans call for part of RHIC's infrastructure, including one of its ion rings, to be reused in constructing the Electron-Ion Collider. Summary: RHIC's closure marks the end of active collisions but not the end of the science derived from its data. Large data sets from the final campaigns will be analyzed in the coming years, and construction of the Electron-Ion Collider is planned using elements of RHIC's infrastructure over the next decade, preserving and extending the laboratory's role in nuclear and particle physics.