Radiation Detectors for Safety

• Terrorism - spread of nuclear material by a "dirty bomb" or other means
• Nuclear accidents - Nuclear power plant releases, spills of transported nuclear material, etc.
• Naturally occuring radiation - radon, uranium, etc.

First, a brief discussion of the three types of ionizing radiation:

• Alpha Particles: Helium nuclei, generally emitted from heavy elements such as uranium and thorium. Alpha particles only travel a few inches in the air, and can be stopped by a piece of paper. Outside the body, they are mostly harmless, as outer layers of dead skin completely block them. But if ingested, they can cause massive cellular and DNA damage, due to the fact that they blast a very small area with very high levels of radiation.

• Beta Rays: Electrons moving at extremely high (often relativistic) speeds. They are more penatrating than alpha particles. They can pass through light elements, such as paper and aluminum (but only small thicknesses). Outside the body, they can cause damage to the eyes and skin. Inside, they can cause major damage, much like alpha particles.

• Gamma Rays: Electromagnetic waves, similar to light, but at a much higher energy. X-rays are identical to gamma rays. They are much more penetrating than alpha or beta radiations. High energy gamma rays can pass through several inches of metal. They can cause damage to all parts of the body, due to the ability to penetrate skin, tissues, bones, and organs.