Brookhaven Collider: New Machine Rises From the Ashes

After 25 years of operation, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in Upton, New York, has concluded its groundbreaking research, marking the end of an era for particle physics in the United States. The collider, which recreated conditions similar to those just moments after the Big Bang, has left a legacy of discoveries about the fundamental structure of matter and the early universe. However, this closure isn’t an end to research at the site, but rather a transition, paving the way for a next-generation collider.

RHIC’s primary function was to collide heavy ions, such as gold nuclei, at nearly the speed of light. These collisions generated incredibly high temperatures and densities, briefly recreating the quark-gluon plasma (QGP) – a state of matter believed to have existed in the universe less than a millionth of a second after its birth. Experiments at RHIC, beginning in the 2000s, unveiled surprising insights into this primordial soup, helping scientists understand the origins of the particles that eventually formed stars, galaxies and everything we see today.

The final days of RHIC saw scientists shifting to proton collisions to gather as much data as possible before the shutdown ceremony on February 6, 2026. According to accelerator physicist Wolfram Fischer, RHIC “had a spectacular run that exceeded expectations.” The decision to close RHIC wasn’t due to a lack of success, but rather to make way for a more advanced facility.

The future of particle physics at Brookhaven lies with the planned Electron-Ion Collider (EIC). While RHIC focused on colliding heavy ions, the EIC will collide electrons with ions. This different approach will allow scientists to probe the internal structure of protons and neutrons with unprecedented precision. The EIC aims to build upon the findings of RHIC, further unraveling the mysteries within these subatomic particles.

The STAR detector, a house-sized instrument integral to RHIC’s operations, captured the aftermath of these high-speed collisions. Physicist Alex Jentsch described the final moments of operation as a time for “either celebrate or grieve.” The detector, a complex network of wires, tubes, electronics, and particle-detection systems, meticulously recorded the paths and properties of the particles created in the collisions. The data collected by STAR and other detectors at RHIC will continue to be analyzed for years to come, yielding further insights into the fundamental laws of physics.

The sPHENIX detector, an upgraded version of the original PHENIX experiment, recently passed a crucial “standard candle” precision test, signifying its readiness for science. This upgrade, approved in 2015, focuses on studying jets and heavy flavors of quarks, complementing research conducted at the Large Hadron Collider (LHC) at CERN in Switzerland. The sPHENIX detector will help explore the properties of the quark-gluon plasma, providing a deeper understanding of the conditions that existed in the early universe.

The closure of RHIC marks the end of the only operating particle collider in the United States and a unique collider globally. While the LHC remains the world’s leading particle physics facility, RHIC played a crucial role in complementing its research, particularly in the study of heavy-ion collisions and the quark-gluon plasma. The transition to the EIC represents a continued commitment to pushing the boundaries of our understanding of the universe, even as one chapter closes and another begins.

The research conducted at RHIC has not only advanced our understanding of the fundamental building blocks of matter but has also spurred technological innovations in areas such as detector technology and data analysis. The legacy of RHIC will continue to inspire future generations of scientists as they embark on the quest to unravel the mysteries of the cosmos.