- #1
- 22,643
- 7,694
I was reading an old thread - Radiation Damage In metals from Gamma rays - https://www.physicsforums.com/threads/radiation-damage-in-metals-from-gamma-rays.826449/ The thread is long dormant and wasn't productive, but based on what I've learned over the last 5 years, I would change my response to indicate that gamma radiation shouldn't be ignored/dismissed, although apparently it has been somewhat. A colleague showed me some radiographs that could only be explained by the presence of gammas, which lead to some of the research I'm now doing.
A useful resource - https://www.oecd-nea.org/jcms/pl_19620 NEA/NSC/DOC(2015)9 - but it does not address gamma radiation.
Gammas are significant due to the interaction with electrons by the photoelectric effect (low energy), Compton Scattering (moderate energy), and pair production (E > 1.022 MeV). As neutron energy increases, pair production becomes more probable, particularly in the presence of high Z atoms, e.g., Zr, Nb, W, U, Pu. It is the Compton electrons and positron-electron pairs that are significant (I use a term 'Compton cascade'). One challenge in understanding the influence of gamma radiation in a reactor is the presence of neutrons, which cause a lot of damage through atomic displacements. For every fission event, there are two or three neutrons, and either 7 or 8 prompt gammas, not including decay gammas (from fission products) and gammas from radiative capture. Obtaining an approximate neutron energy spectrum (0.01eV to 10 MeV) for a given lattice is relatively simple compared to obtaining a gamma energy spectrum, which is considerable more complex.
Another good reference - Fundamentals of Radiation Materials Science
https://link.springer.com/book/10.1007/978-1-4939-3438-6 (but not much on gamma radiation effects).
Gary Was has taught a lot of folks now working on the subject.
A useful resource - https://www.oecd-nea.org/jcms/pl_19620 NEA/NSC/DOC(2015)9 - but it does not address gamma radiation.
Gammas are significant due to the interaction with electrons by the photoelectric effect (low energy), Compton Scattering (moderate energy), and pair production (E > 1.022 MeV). As neutron energy increases, pair production becomes more probable, particularly in the presence of high Z atoms, e.g., Zr, Nb, W, U, Pu. It is the Compton electrons and positron-electron pairs that are significant (I use a term 'Compton cascade'). One challenge in understanding the influence of gamma radiation in a reactor is the presence of neutrons, which cause a lot of damage through atomic displacements. For every fission event, there are two or three neutrons, and either 7 or 8 prompt gammas, not including decay gammas (from fission products) and gammas from radiative capture. Obtaining an approximate neutron energy spectrum (0.01eV to 10 MeV) for a given lattice is relatively simple compared to obtaining a gamma energy spectrum, which is considerable more complex.
Another good reference - Fundamentals of Radiation Materials Science
https://link.springer.com/book/10.1007/978-1-4939-3438-6 (but not much on gamma radiation effects).
Gary Was has taught a lot of folks now working on the subject.