Since 1999, a collaboration led by Carl Collins (University of Texas at Dallas) has been reporting evidence for the x-ray induced release of energy stored in an unusually long-lived nuclear isomer of hafnium-178. Collins’s claims have aroused a public debate whose acrimony reflects issues that go far beyond the interesting but normally staid physics of nuclear isomers.
The Texas collaboration purports to have demonstrated that a 10-keV x-ray photon can precipitate a prompt 2.45-MeV gamma-ray cascade as the isomer 178Hfm2 relaxes to the stable nuclear ground state. Normally, the isomer’s halflife is 31 years. Such triggered release of nuclear energy, if it is indeed possible, raises the prospect of radically new weapons and energy-storage technologies.
But a number of prominent nuclear physicists publicly characterize Collins’s claims as quite implausible a priori and completely unproven. They look with dismay on the funds already committed, and on the much larger...
