出典:Wikipedia
出典:『Wikipedia』 (2011/07/16 17:53 UTC 版)
The nucleus is the very dense region consisting of nucleons (protons and neutrons) at the center of an atom. Almost all of the mass in an atom is made up from the protons and neutrons in the nucleus, with a very small contribution from the orbiting electrons. It was discovered in 1911, as a result of Ernest Rutherford's interpretation of the famous 1909 Rutherford experiment performed by Hans Geiger and Ernest Marsden, under the direction of Rutherford. The proton–neutron model of nucleus was proposed by Dmitry Ivanenko in 1932.