Beta particles

The production of beta particles is termed beta decay. They are designated by the Greek letter beta (β). There are two forms of beta decay, β− and β+, which respectively give rise to the electron and the positron.

β− decay (electron emission)

Beta decay. A beta particle (in this case a negative electron) is shown being emitted by a nucleus. An antineutrino is always emitted along with electrons (not shown). Insert: in the decay of free neutron, a proton, an electron (negative beta ray), and electron antineutrino are produced An unstable atomic nucleus with an excess of neutrons may undergo β− decay, where a neutron is converted into a proton, an electron and an electron-type antineutrino (the antiparticle of the neutrino):

n → p + e− + νe

This process is mediated by the weak interaction. The neutron turns into a proton through the emission of a virtual W− boson. At the quark level, W− emission turns a down-type quark into an up-type quark, turning a neutron (one up quark and two down quarks) into a proton (two up quarks and one down quark). The virtual W− boson then decays into an electron and an antineutrino. Beta decay commonly occurs among the neutron-rich fission byproducts produced in nuclear reactors. Free neutrons also decay via this process. Both of these processes contribute to the copious numbers of beta rays and electron antineutrinos produced by fission reactor fuel rods.

β+ decay (positron emission)

Unstable atomic nuclei with an excess of protons may undergo β+ decay, also called positron decay, where a proton is converted into a neutron, a positron and an electron-type neutrino:

p → n + e+ + νe

Beta plus decay can only happen inside nuclei when the absolute value of the binding energy of the daughter nucleus is greater than that of the mother nucleus, i.e., the daughter nucleus is a lower-energy state.

Wikipedia: The free encyclopedia [online]. 2014 [cit. 2014-01-23]. Source: http://www.en.wikipedia.org/

Interesting educational videos:

Simply Explanation of beta radiation

Ionizing radiation: Beta radiation