RHIC is the first machine in the world capable of colliding heavy ions, which are atoms which have had their outer cloud of electrons removed. RHIC primarily uses ions of gold, one of the heaviest common elements, because its nucleus is densely packed with particles.
RHIC collides two beams of gold ions head-on when they're traveling at nearly the speed of light (what physicists call relativistic speeds). The beams travel in opposite directions around RHIC's 2.4-mile, two-lane"racetrack."At six intersections, the lanes cross, leading to an intersection. When ions collide at such high speeds fascinating things happen.
If conditions are right, the collision"melts"the protons and neutrons and, for a brief instant, liberates their constituent quarks and gluons. Just after the collision, thousands more particles form as the area cools off. Each of these particles provides a clue as to what occurred inside the collision zone. Physicists sift through those clues for interesting information.