Footnotes on particle-beam weapon history

I read with interest Silvan Schweber's article entitled "Defending Against Nuclear Weapons: A 1950s Proposal" in the April 2007 issue of PHYSICS TODAY (page 36).

Schweber outlines Robert R. Wilson's ambivalence in generating proposals to look at military applications of accelerators while at the same time exerting a considerable effort in putting the brakes on the spread and applications of nuclear weapons. Schweber cites Wilson's proposals to utilize high-energy electron or proton beams as particle-beam weapons for various applications, and he describes a meeting on 3 October 1952, which I attended, that was called by the Atomic Energy Commission in response to those proposals. Attendees discussed particle-beam weapons, but Schweber writes, "I do not know what the subsequent history of Wilson's machine was. The AEC and the US Department of Defense continued to show interest in the idea at a 1953 meeting and in a subsequent report, but there is no available unclassified documentation of the plan ever being implemented."

The AEC subsequently established a project called Hydra to take a look at particle-beam weapons. I made an analysis (which would be trivial today) calculating the multiple scattering of charged hadron beams in the atmosphere and concluded that such multiple scattering would make proton beams infeasible as weapons unless they had an energy of many GeV. Also, some serious beam-stability problems emerged.

Interest in particle-beam weapons was revived in 1958 by the Advanced Research Projects Agency (ARPA) as Project Seesaw. However, the laws of physics have prevented practical realization of a particle-beam weapon, and the ARPA project was cancelled after a decade and very substantial expenditure.

Schweber speculates that the generous postwar governmental support of accelerators was partly motivated by possible military applications. Although that may have been so in the minds of some officials, I suspect that few informed people harbored any illusions that the great machines would serve any purpose other than basic science or applications to medicine.