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The Question

(Submitted February 09, 1998)

I know that gamma rays were discovered shortly after alpha and beta particles, but who is given credit for the discovery?

The Answer

Paul Villard, a French physicist, is credited with discovering gamma rays. Most sources put this in 1900, although I've seen a few sources use 1898. Villard recognized them as different from X-rays (discovered in 1896 by Roentgen) because the gamma rays had a much greater penetrating depth. It wasn't until 1914 that Rutherford showed that they were a form of light with a much shorter wavelength than X-rays.

A good web site on the history of the discovery of radiation, written by Michael Fowler at University of Virginia, is:

Jim Lochner
for Ask an Astrophysicist

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