Beta radiation is one of three kinds of radioactive emission . Beta particles were first isolated in about 1900, when the British physicist, Ernest Rutherford, subjected radioactive emissions to an electric field. It was also found that Beta particles were nearly 100 times more penetrating than Alpha particles.

Beta particles can be seen as electrons, that is why they are sometimes called ‘Speedy electrons’. According to current theory, Beta emission is accomplished by the transformation of a Neutron into a Proton, thus resulting in an increase in nuclear charge (or atomic number) of one unit. The mass of the electron (± 0.00054 mass units) is negligible; thus the isotope which results from the original element has the same mass but a higher atomic number e.g.

Thorium-234 emits Beta particles, which are electrons. The Neutron changes to a Proton and an Electron. The Electron is emitted. The new substance, an isotope of Thorium, has the same mass number, 234, but the new atomic number is 91.

Beta particles can move several metres before being stopped by ± 5mm thick Aluminium. They do not ionise very strongly in air. The speed at which these particles move is just less than that of light, therefore just less than 3 X 10⁸ m/s. Beta particles can easily be deflected by a magnetic field.

For safety reasons, we have to remember that Beta particles are much more penetrating than Alpha particles. High energy Beta particles can penetrate to a depth of about a centimetre in your body’s tissue. Eye and skin damage is possible if the radiation source is strong; therefore Beta sources do present an external radiation hazard.

The energy of Beta radiation from the majority of nuclides lies in the range 0.5 MeV to 3.5 MeV but like all science there are some exceptions. Materials with high atomic numbers, such as Lead, are the most effective in stopping Beta particles.

did you know?


beta n.

the second letter of the Greek alphabet (B, b).

related links


read about the alpha particle
read about the gamma particle

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