Clear Science!

We talked about ionizing radiation, discussing alpha particles, beta particles, and gamma rays. Alpha and beta are both particles, with mass, but gamma rays are better thought of as waves. What can we say about that?

Gamma rays are electromagnetic radiation, which is another way of using the word “radiation.” You know a lot about electromagnetic radiation, because light is electromagnetic radiation. Gamma rays are the same stuff as light, but with extremely high frequency and low wavelength. Above, some waves are sketched, showing what frequency and wavelength mean.

Electromagnetic radiation with high frequency is dangerous, because it has high energy (because it’s “waving” so fast). This makes it ionizing radiation, i.e. a dangerous kind of radiation.

We talked about alpha particles, beta particles, and gamma rays, which are types of ionizing radiation. You often see pictures like the one up above, which show you what each of these types of radiation can go through.

Alpha particles are heavy and big, and won’t go through paper, clothes, or skin. Beta particles will go through those things, but are stopped by a relatively thin sheet of metal.

Gamma rays, however, are rays not particles. (Well, more properly they’re photons, like light. So they’re kind of particles.) They are only stopped by a massive thickness of heavy material, like the lead around a bank vault or several feet of dirt.

You might thus conclude that gamma radiation is the most dangerous and alpha radiation is the least?  Well …

If we ask: What is radiation?, we first have to figure out what we mean by that. Let’s say “radiation” refers to the bad stuff that comes from radioactive substances or devices. Examples of radioactive things are: radon gas, nuclear fallout, radioactive waste, etc.

This is properly called “ionizing radiation.” But most of the time people just call it “radiation.”

It occurs via waves or particles emitted from radioactive things. The most common examples have names. Alpha particles or alpha radiation are collections of 2 protons and 2 neutrons (a.k.a. helium nuclei). Beta radiation is a stream of electrons. Gamma radiation is an emission of gamma waves.