The nuclear force

The nuclear force holds atomic nuclei together. When protons and neutrons are a femtometre apart, the nuclear force between them is powerfully attractive. If you could turn this powerfully attractive force off, an atomic nucleus would explode into a spray of protons and neutrons. That’s because there’s an electromagnetic force between the protons, and it’s powerfully repulsive. In stable nuclei, the forces are in balance. But as Rod Nave says on his most excellent hyperphysics website, when the balance is broken the resultant radioactivity yields particles…

Continue Reading

The neutron

There’s a nice potted history of the discovery of the neutron on the Nobel website. It mentions the great Ernie Rutherford who discovered the proton in 1917. He knew all about Prout's hypothesis wherein the atomic weights of various elements were integer multiples of the atomic weight of hydrogen. However Rutherford also knew that the atomic number, the number of protons, was circa half the atomic weight. So in 1920 he suggested that this disparity was due to neutral particles called neutrons. The evidence of beta…

Continue Reading

The nuclear disaster

The nuclear force is the force that keeps protons and neutrons together in atomic nuclei. It is often said to be due to a pion exchange proposed by Hideki Yukawa in 1935. His Nobel prize lecture Meson theory in its developments gives some background: “As pointed out by Wigner1, specific nuclear forces between two nucleons, each of which can be either in the neutron state or the proton state, must have a very short range of the order of 10-13 cm, in order to account for…

Continue Reading
Close Menu