Consists primarily of electrons emitted from radioactive nuclei, but the term also covers streams of positrons (positively charge electrons). The properties of a beam of beta particles seem not to be quite the same as those of a beam off electrons in cathode ray tube, for instance. This is because electrons in a cathode ray or fine beam tube are accelerated through a few thousand volts, whereas electrons expelled from nucleus during beta decay have about a thousand times as much energy. Beta particles are deflected by magnetic fields, but a much stronger field is needed to give even modest deflection with the lower speed electron beam. Beta particles penetrate a thin aluminium sheet where a low speed electron beam would do no more than warm its surface. The high penetrating power makes beta radiation severe health hazard to any animal exposed to even a modest dose. Deep body damage is possible.
Alpha particles emitted from any one radioactive nuclide all have much the same energy and consequently the same range in air. But the diagram shows how beta particles are emitted with a range of energies from zero (improbable) to a maximum value (also improbable). The reason is that in beta decay a second particle is emitted from the nucleus (the antineutrino) and the available energy is shared more or less randomly between the two particles.
Beta radiation can be detected and monitored efficiently with a GM tube attached to a scaler.
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