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The Wikipedia said that nuclear fission is triggered by neutron binding energy. For example, a neutron captured by U-235 releases about 7 MeV, which is enough for the nucleus to overcome the potential barrier of nuclear fission. Neutron capture by U-238 releases slightly less energy, which needs to be compensated by the kinetic energy of the neutron.

So I am curious what if the energy is not provided by neutrons. For example, if we bombard uranium with high energy gamma rays of 7 MeV, will it trigger nuclear fission in a similar manner?

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    $\begingroup$ As usual, the place to go is the Evaluated Nuclear Data File database. I use the mirror at Brookhaven (nndc.bnl.gov/endf). The Reaction examples are all for neutrons ("n"), but it holds gamma cross sections as well, using "g". So, selecting "U-235" for nucleus, "g,*" for reaction, and "sig" for cross sections will get you a list of reaction cross sections that you can plot. $\endgroup$ Commented yesterday
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    $\begingroup$ On a related note, photodisintegration is important in the stellar nucleosynthesis of heavier elements. See en.wikipedia.org/wiki/Neon-burning_process & astronomy.stackexchange.com/q/36719/16685 & links therein. $\endgroup$ Commented 23 hours ago
  • $\begingroup$ @PM2Ring photodisintegration is related, but different process where the photon suppliesall of the energy needed. $\endgroup$ Commented 22 hours ago

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Yes. This is known as photofission and was first reported for uranium in

Haxby et al., "Photo-Fission of Uranium and Thorium". Phys. Rev. 59, 57–62 (1941).

The authors irradiated a film of natural uranium with 6.3 MeV gamma rays (which were produced by bombarding fluorine with protons) and observed fission events induced by the gamma rays.

Note that the terminology of the paper is somewhat antiquated. In particular, "ionium" is what we now call thorium-230, "uranium II" is uranium-234, and "actino-uranium" is uranium-235.

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