Step 4: Be Safe: Use Shielding!
First let’s start with gamma rays. In certain radionuclides the atom’s nucleus is left in an excited state after beta or alpha decay. This energy is then released via a very high energy photon. By high energy I mean several MeV, and due to that gamma rays are very penetrative. It takes quite a lot of material to stop them, so lead is often the material of choice for gamma shielding. If for some reason you have a very active gamma source use plenty of lead to shield it. Something like 5cm or more of that grey metal should be sufficient.
The other type of electromagnetic radiation I have to discuss is x-rays. X-Rays are produced when electrons dump a large amount of energy into a single photon, thus creating a very high energy light particle. X-Rays are a lot like regular light: they travel in straight lines, can be reflected somewhat, and scatter in the air much like a green laser beam. When experimenting with x-rays, always make sure your lab is of light construction. While cinderblock walls are great for stopping x-rays from escaping your lab, they are also great for reflecting them back at you! It’s better to have them escape rather than to have them bounce around.
When possible, be sure to either point your x-ray beams down to the earth or up in the air: anywhere where it is unlikely to be intercepted by an animal or human. NEVER power up an x-ray tube in a shared residence or an apartment without full knowledge that the radiation will be contained, and NEVER intentionally expose yourself to x-radiation.
It is important to shield yourself from x-rays to prevent overexposure! The amount of shielding required is entirely dependent on the energy and quantity of x-rays being stopped. Lead is the ideal shield for x-rays because it is cheap, easily workable and has a high nuclear charge; something that lets it absorb electromagnetic radiation very well. For convenience I have prepared this chart of energy vs. attenuation vs. amount of lead needed using the standards set by the International Atomic Energy Agency. [Image 1]