We survey the production of electron, muon and tauon pairs in collisions between nuclei at ultra-relativistic energies. Such studies enhance our understanding of the role of the vacuum in field theory, and provide essential input for several experimental programs. A variety of models for the nuclear and nucleon form factors have been considered, revealing some degree of sensitivity to assumptions about sub-nuclear structure. We predict that the cross sections, even at high invariant masses and transverse momenta, are large on hadronic scales, and should act as useful probes of nuclear and nucleon form factors. 21 refs., 5 figs.

There has been considerable progress in gluonia investigations and their analysis. As requested by the Convenor, Rich Galik, I will cover the highlights of various conference papers and related work in an integrated manner which incorporates a review of the present state of glueballs (gluonia) to the extent space limitations allow. There are four general methods of searching for glueballs: J//psi/ radiative decay (iota, theta, xi(2.2)); OZI violating (g/sub T/, g/sub T/', g/sub T//double prime/); hadronic interaction pattern recognition of extra isosinglet states in addition to q/bar q/ nonets, iota, G, S*', g/sub s/; and double Pomeron exchange. These will be reviewed. 4 refs., 4 figs.

This paper discusses a modified version of the PACER concept for power and nuclear material production, which changes the working fluid in the cavity from steam to the molten salt, LiF + BeF/sub 2/. In the PACER concept, a 20-kt peaceful nuclear explosion is contained in a cavity about 200 m in diameter, filled with 200 atm of 500/degree/C steam. Energy from the explosion is used to produce power, and the neutrons are used to produce materials such as /sup 233/U, Pu, /sup 60/Co, and T. The present idea is to modify the PACER concept in three ways, to improve the practicality, predictability, and safety of power production from this technology and thus improve public acceptance of this power source. These improvements are line the cavity with steel; replace the steam with molten salt; and reduce the explosive yield to about 2 kt. This concept is the only fusion power concept where the underlying technology is proven and in hand today. 9 refs., 3 figs., 1 tab.