What was the source of the particles used by Rutherford in the experiment that showed the existence of the nucleus?
1 Answer
Sources I have read describe the source as a box of lead containing the radioactive source into which a small hole had been drilled to serve as a collimator, and release a precisely defined beam of alpha particles.
Explanation:
Ernest Rutherford was, in 1911, the world's leading authority on radioactivity, having been the one to recognize that alpha radiation was the release of a small, charged particle from within certain atoms.
Now, as he contemplated a way to investigate the structure of the atom, he knew he would require a particle that was very much smaller than an atom, and one that possessed a great amount of kinetic energy, in order to be able to pass through even the thinnest foil of gold. Such a particle would still encounter thousands of gold atoms during the passage, and the high kinetic energy would ensure that his "bullet" would make it through the target.
Most reports suggest that he used an alpha emitter such as the Curie's new-found radium as a source. He encased the radioactive sample in a box of lead, into which he then drilled a tiny hole. Alpha particles would spray in all directions from the source, but only those travelling along a line that enabled them to pass through the hole would emerge. Thus, he had a type of alpha-particle gun to aim at the foil.
