Relativistic Heavy-Ion Physics Without Nuclear Contact

Abstract

An increasing number of physicists are investigating nuclear collisions at relativistic energies. (See figure 1.) Accelerators completely devoted to the study of these collisions (such as the Relativistic Heavy Ion Collider at Brookhaven National Laboratory) are under construction. So are hadron colliders (such as the Large Hadron Collider at CERN), which can also be used to accelerate heavy ions. The aim of these projects is to study what happens to nuclear matter at high pressures and temperatures. The expectation is that such experiments will access information that can test important predictions of quantum chromodynamics—for example, a nuclear matter transition from a mixture of quarks and gluons to hadrons, as occurred in the first moments of the universe according to the Big Bang theory.