For three years now, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been providing experimenters with colliding beams of heavy nuclei at ultrarelativistic energies as high as 100 GeV per nucleon. The purpose of this extraordinary new accelerator is to seek out and explore new high-energy forms of matter and thus continue the centuries-old quest to understand the nature and origins of matter at its most basic level.
Early results from the RHIC experiments reveal new nuclear phenomena at temperatures and densities well into the range where quarks and gluons—rather than nucleons and mesons—are expected to define the relevant degrees of freedom. The first measurements of head-on collisions at RHIC energies, with nuclei as heavy as gold, have already taken us a major step toward the long-sought quark-gluon plasma.
Since the discovery of quarks in the 1960s, the core questions in nuclear and particle physics have evolved...
