Beta radiation

Beta radiation occurs as  the result of beta decay (β-decay), a type of radioactive decay in which a proton is transformed into a neutron, or vice versa, inside an atomic nucleus. 


A diagram showing a nucleus emitting an electron. image: wikipedia

This process allows the atom to move closer to the optimal ratio of protons and neutrons. As a result of this transformation, the nucleus emits a detectable beta particle, which is an electron or positron. 

Beta decay is mediated by the weak force. There are two types of beta decay: 

  • beta minus and 
  • beta plus. 

Beta minus (β) decay

Beta minus (β) decay produces an electron and electron antineutrino, while beta plus (β+) decay produces a positron and electron neutrino; β+ decay is thus also known as positron emission. 

An example of electron emission (β− decay) is the decay of carbon-14 into nitrogen-14:

This produces high energy electrons and an anti neutrino (a symbol with a bar over the top indicates the antiparticle)

In this form of decay, the original element becomes a new chemical element in a process known as nuclear transmutation. This new element has an unchanged mass number A, but an atomic number Z that is increased by one. 

As in all nuclear decays, the decaying element (in this case C14) is known as the parent nuclide while the resulting element (in this case N14) is known as the daughter nuclide. The emitted electron or positron is known as a beta particle.

Beta plus (β+) decay

An example of positron emission (β+ decay) is the decay of magnesium-23 into sodium-23:

In contrast to β decay, β+ decay is accompanied by the emission of an electron neutrino. β+ decay also results in nuclear transmutation, with the resulting element having an atomic number that is decreased by one.

Source based on: Beta decay. (2015, June 16). In Wikipedia, The Free Encyclopedia. Retrieved 06:18, June 18, 2015, from