Radiation comes in a variety of flavours.
For the sake of simplicity, let’s focus on three that come from radioactive decay: alpha particles, beta particles, and gamma rays.
Imagine our pellet of radioactive material. As we looked at in Part 1, the atoms making up this material will lose a small amount of their mass as a bullet of radiation that shoots into the wide world . The type of radiation the pellet emits depends on the unstable material making up the pellet.
If our pellet of material is undergoing alpha decay, then its atoms will be losing its mass in the form of alpha particles. These are the underachievers of the radiation family (though have an insidious dark side that we’ll see later; a bit like Scar from the Lion King.) You are easily shielded from them by a sheet of paper. Actually, even thick air or ever your skin is enough to stop these particle pushovers.
Beta decay creates beta particles, which have a higher energy and higher speed, and can happily pass through you like fermented prunes. That said, beta particles will be stopped by a material with a sufficiently high density, such are a sheet of aluminium.
A material undergoing gamma decay is really nasty. Its mass decays into gamma rays that easily penetrates skin, aluminium sheeting, concrete, One Nation supporters, and will only be stopped by a material that is sufficiently dense; say, a chunk of lead.
As the observers of this pellet of radioactive material, we are concerned about which type of radiation is being emitted. All three have the potential of doing damage to the cells in our body, but if it is weak like alpha particles, then the chances of it travelling the distance to us let alone penetrating our body’s cells is small. Beta particles have a higher risk, but the radiation to beware of is gamma rays, smashing through your body like a very small but high-speed bullet.
Carrying on with our accident at our hypothetical nuclear powerplant, the next questions we and any Walkley-winning journalist should ask:
o If the plant is leaking radioactive material, what sort of radiation is it emitting?
Knowing what sort of radiation is being emitted, then we can make an estimate of how dangerous it is to be exposed to it. And this is the subject of Part 3.