A future particle accelerator designed to collide electrons with protons and nuclei to probe their internal structure.The Electron-Ion Collider (EIC) is a planned particle accelerator designed to smash electrons into protons and heavier atomic nuclei. Unlike earlier colliders that probed the internal structure of matter with point-like particles, the EIC will provide a uniquely clean and precise view of the strong nuclear force — the interaction that binds quarks and gluons inside protons and neutrons. It aims to answer fundamental questions about how mass emerges from the energy of these particles and how the properties of ordinary matter arise from their complex dance.
The concept was developed over decades, with the design converging in the 2010s. The project was officially endorsed by the U.S. National Academies in 2018, and Brookhaven National Laboratory was selected as the site in 2020.
The EIC will accelerate two beams in opposite directions: one of electrons, the other of protons or nuclei. When they collide, the electron acts as a fine probe, scattering off the internal constituents of the nucleon. By varying the collision energy and detecting the scattered electron and other debris, physicists can map the distribution of quarks and gluons with unprecedented precision, including their spins and momenta.
Beyond fundamental physics, the EIC's detector and accelerator technologies will advance medical imaging, materials science, and high-performance computing.
The EIC will be the first collider to use polarized electrons and polarized protons, allowing scientists to study how the spin of the proton is carried by its internal quarks and gluons.













