Take the quarks as an example. In addition to the pair of quark types known as "up" and "down," which make up the core of atomic nuclei, there exist two additional quark pairs: "charm" and ...

The emission of beta radiation provides evidence that neutrons and protons are made up of quarks. Beta (\(\beta^-\)) decay is the release of an electron by the change of a neutron to a proton.

Here is the equation for the alpha decay of radon-219 into polonium. Beta decay involves the conversion of a down quark to an up quark. This changes a neutron into a proton plus an electron.