Perspective on relativistic nuclear collisions

The importance of experiments detecting more than one particle is pointed out. The production of nuclei far from stability in peripheral collisions and the expectations for the explosive disassembly of dense nuclear matter (nuclear fireball) and some evidence for it are related. Pion interferometry concerns the measurement of correlations in the momentum and energy of two identical pions; the subject is discussed in relation to incoherent production, coherent production, partially coherent production, final-state interactions, impact parameter average, and outlook. Much of the paper deals with an assessment of the possibility of determining the form of the hadronic spectrum in the high-mass region through nuclear collisions at ultrarelativistic energies. The subject is developed under the following topics: perspective, the initial fireball, isoergic equilibrium expansion of the fireball, quasi-dynamical expansion, quark matter, and the mass degree of freedom. The quasi-dynamical model obtained indicates that certain parameters, such as the ..pi../N and K/N ratios at high kinetic energy, will survive the collision; therefore, a determination of the asymptotic form of the hadron spectrum probably can be made by studying nuclear collisions at very high energies (10 GeV/nucleon in the center of mass). 16 figures. (RWR