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The Spring 2011 issue of The Earth Scientist is focused on modernizing seismology education. Thanks to IRIS, you can download this issue for free as a pdf. Print copies are available in our online store.
Gamma rays are the highest energy form of electromagnetic radiation.
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Windows to the Universe

Gamma Ray Radiation

Gamma rays are an extremely high-energy form of electromagnetic (EM) radiation. Gamma ray radiation has a much, much shorter wavelength than visible light, so gamma ray photons have much, much higher energies than photons of light do.

Gamma rays lie at the extreme high-energy end of the electromagnetic spectrum. X-rays, which have slightly lower energies than gamma rays, are the neighbors of gamma rays along the EM spectrum. In fact, the spectral ranges of hard X-rays and gamma rays overlap. Gamma rays have wavelengths of about 100 picometers (100 x 10-12 meters) or shorter, or energies per photon of at least around 10 keV. This type of electromagnetic wave oscillates with a frequency of 3 exahertz (EHz or 1018 hertz) or higher.

There is no sharp distinction between the highest energy X-rays and the lowest energy gamma rays. The distinction between X-rays and gamma rays is actually based on the origin of the radiation, not on the frequency or wavelength of the electromagnetic waves. Gamma rays are produced by nuclear transitions, while X-rays are the result of accelerating electrons. Photons with energies between about 10 keV and a few hundred keV can be either hard X-rays or gamma rays.

Last modified July 13, 2005 by Randy Russell.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA