X-rays were discovered in 1895 by Wilhelm Conrad Rontgen at the University of Wurzburg, Bavaria.
He noticed that some crystals of barium platinocyanide, near a discharge tube completely enclosed in black pepper, became luminescent when the discharge occurred.
By examining the shadows cast by the rays, Rontgen traced the origin of the rays to the walls of the discharge tube.
In 1896, Campbell-Swinton introduced a definite target (platinum) for the cathode rays to hit; this target was called the anticathode.
For his work x-rays, Rontgen received the first Nobel prize in physics, in 1901. It was the first of six to be awarded in the field of x-rays by 1927.
The obvious similarities with the light led to the crucial tests of established wave optics: polarization, diffraction, reflection and refraction.
With limited experimental facilities, Rontgen and his contemporaries could find no evidence of any of these; hence, the designation “x” (unknown) of the rays, generated by the stoppage of anode targets of the cathode rays, identified by Thompson in 1897 as electrons.
The nature of x-rays was the subject of much controversy. In 1906, Barkla found evidence in scattering experiments that x-rays could be polarized and must therefore by waves, but W.H Bragg’s studies of the produced ionization indicated that they were corpuscular.
The essential wave nature of x-rays was established in 1912 by Laue, Friedrich, and Knipping, who showed that x-rays could be diffracted by a crystals (copper sulfate pentahydrate) that acted as a three dimensional diffraction grating.
W.H Bragg and W.L Bragg (father and son) found the law for the selective reflection of x-rays. In 1908, Barkla and Sadler deduced, by scattering experiments, that x-rays contained components characteristics of the material of the target; they called these component K and L radiations.
History of X-ray
