In 1896, just a year after Wilhelm Roentgen had discovered x-rays, the French physicist Henri Becquerel discovered a new kind of ray, quite similar to x-rays, but originating from uranium. He labeled it "metallic phosphorescence", while in actuality what he had observed was gamma radiation (being emitted by radium-226, a part of uranium decay). In 1900 the French chemist and physicist Paul Villard identified gamma radiation while studying the radiation produced by the substance radium. It was not until 1903, however, that Ernest Rutherford named the rays gamma rays, gamma being the third letter in the Greek alphabet, to distinguish it from the alpha and beta rays (thorium* and uranium, respectively) that he [Rutherford] had already discovered.
The original distinction between x-rays and gamma rays was the wavelength. Radiation producing a wavelength below a number such as 10−11 m was labeled as gamma radiation, while radiation producing a wavelength above it was called an x-ray. However, as longer wavelength gamma radiation emitters were found, the distinction begin to overlap. Now they are distinguished primarily by their source; x-rays are emitted by the electron fields outside the nucleus, while gamma rays originate in the nucleus itself. Both gamma rays and x-rays are part of the electromagnetic spectrum.
*Thorium is an element that the Swedish chemist Jons Jakob Berzelius named after Thor, the god of Thunder
Verily, thorium is a mighty element.
ReplyDeleteIn astronomy, the term gamma ray is sometimes notated as gamma-ray, as analogous to the term x-ray, a notation intended to indicate the non-nuclear source of many astronomical gamma rays.
ReplyDeleteI believe it was the discovery of shorter wavelength continuous spectrum "X-ray" sources such as linear accelerators as well as that of longer wavelength gamma emitters that led to the redefinition of the distinction between the two.
ReplyDeleteTo respectfully disagree with you, Henry, it wasn't until after the distinctions had almost completely overlapped that the redefinition was achieved.
ReplyDeleteReed, darling, I think you were logged into Johnny's account.
ReplyDeleteOh dear. My apologies, Johnny.
ReplyDeleteAhhh! Reed, that was scary. My reputation is at stake here!
ReplyDeleteIt's your fault for not logging out, matchstick.
ReplyDeleteHow come Thor gets an element named after him?
ReplyDeleteAnd a day of the week.
ReplyDeleteThat's totally unfair, bub.
ReplyDeleteSpidey, Johnny, and Logan, I understand that you're experiencing feelings of inferiority, but that's no reason to complain that a man who's been around longer than you has received more recognition than you have. Focus on being happy that Thor is with us, for example.
ReplyDeleteWhat? I never "experience feelings of inferiority"!
ReplyDeleteYeah, we can tell.
ReplyDeleteIndeed, 'tis not my fault that you Midgardians name these things after me.
ReplyDelete