Published in Nature, Vol. 325, 754 (1986).
Sir - The first published account of success in immobilizing antiprotons in an electromagnetic trap has been the subject of a recent leading article News and Views editorial (Nature, Vol. 324, 299; 1986). Although this article gives a good overview of the scientific meaning of this historical achievement, it gives in our view a rather misleading perspective on its likely military significance.
It is true that for some applications of antimatter, such as antiballistic missile or spacecraft propulsion, relatively large amounts of antiprotons are required. For most other cases, the useful amounts are usually much smaller. For example, we have calculated that less than a microgram of antiprotons is sufficient to trigger a thermonuclear explosion or pump a powerful X-ray laser [1].
But antimatter is not only the most powerful of all high-explosives, it is also the only feasible portable source of muons. In every antiproton annihilation, on the average three muons are produced. These could be used to induce muon-catalysed fusion reactions in a deuterium-helium-3 mixture, an attractive solution for a low-weight neutron-free space nuclear reactor that could be operated in a continuous or pulsed mode.
Furthermore, by collecting and cooling the muons (a relatively easy task compared with that of cooling antiprotons) a very intense beam could be formed and sent into the atmosphere to guide, over a range of more than 10 km, a series of powerful electron or proton beam pulses towards a target. More simply, stopping the muons in a suitable material would generate an extraordinarily effective X-ray lasing medium, for the two microseconds lifetime of the muonic-atoms.
In outer space, a very low intensity burst of antiprotons would be most suitable for active warhead/decoy discrimination. In this and the two previous examples, the needed amount of antiprotons is of the order of nanograms per engagement. Conservative estimates of the technical problems involved in producing and manipulating microgram amounts of antimatter per day, show that known technology is only a couple of orders of magnitudes away from meeting the challenge [2,3].
We are very much concerned by the implications for nuclear weapons proliferation of the undisputable scientific feasibility of several antimatter weapon concepts. To develop such weapons would add considerable impetus to the current arms race. We call for an immediate ban on all antimatter related research, especially since this work is fundamental to many fourth-generation nuclear weapon systems.
Andre Gsponer and Jean-Pierre Hurni[1] Gsponer A. et Hurni J.-P.: Antimatter weapons, Bulletin of Peace Proposals Vol. 19 (Oslo,1988) 444--450. Gsponer A. and Hurni J.-P.: The physics of antimatter induced fusion and thermonuclear explosions, in G. Velarde and E. Minguez, eds., Proceedings of the 4th International Conference on Emerging Nuclear Energy Systems, Madrid, June 30/July 4, 1986 (World Scientific, Singapore, 1987) 166--169.
[2] Gsponer A. and Hurni J.-P.: Antimatter induced fusion and thermonuclear explosions, Atomkernenergie--Kerntechnik (Independent Journal on Energy Systems and Radiation) Vol. 49 (1987) 198--203.
[3] Augenstein B.W.: Concepts, problems and opportunities for use of annihilation energy," prepared for the United States Air Force, RAND Note N-2302-AF/RC (June 1985). Walgate R.: Defence lobby eyes antimatter, Nature, Vol. 322, 678 (1986).