Radiobiology > Physical Processes > Quanta > Gamma-Rays

Energetic Quanta: Gamma-Rays

Gamma rays…

  • Are emitted from the nucleus to trim excess energy.
  • Tend to carry higher energies than X-rays, but this does not have to be the case

For example, after a larger energy decay particle (e.g. a beta particle) is emitted, the nucleus may still be slightly unstable (i.e., the atom remains in an isomeric or excited state).  Emission of a gamma ray provides a means to lose a smaller amount of excess energy.

Important examples of gamma emitters: potassium-40, cobalt-60, cesium-137, and technetium-99m

Simplified electromagnetic spectrum with relative wavelength scale. 

Photons in the spectrum of visible light are energized at 2 to 3 eV. Contrast this with the energies carried by X-rays and gamma rays - ranging from thousands to millions of electron-volts.


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