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Photofission is a process in which a nucleus, after absorbing a gamma ray, undergoes nuclear fission (splits into two or more fragments).

Very high energy gamma rays have been shown to induce fission in elements as light as tin.[citation needed] Gamma radiation of more modest energies, in the low tens of MeV, can induce fission in traditionally fissile elements such as the actinides uranium, plutonium, and neptunium.[1] Experiments have been conducted with much higher energy gamma rays, finding that the photofission cross section varies little within ranges in the low GeV range.[2]


Photodisintegration (also called phototransmutation) is a similar but different physical process, in which an extremely high energy gamma ray interacts with an atomic nucleus and causes it to enter an excited state, which immediately decays by emitting a subatomic particle.


  1. ^ Delayed neutron yields and spectra from photofission of actinides with bremsstrahlung photons below 20 MeV. D Doré et al 2006 J. Phys.: Conf. Ser. 41 241
  2. ^ Phys. Rev. Lett. 84, 5740–5743 (2000) Photofission of Heavy Nuclei at Energies up to 4 GeV