THREE years ago, New Scientist warned that the US was developing a new kind of quasi-nuclear weapon, the hafnium bomb (16 August 2003, p 4). It relied not on fission or fusion, but on triggering the release of excess energy stored in the distorted nucleus of the isotope hafnium-178, specifically its isomer hafnium-178m2.
This nuclear isomer is radioactive, emitting its excess energy as a gamma ray, with a half-life of 31 years. The Pentagon was supposedly developing a way to trigger that decay in vast numbers of excited hafnium nuclei at once, producing an explosive burst of gamma rays…
