Question

What are the different sizes and health hazards of the three nuclear particles/rays?

Answer 1

The three main types of radiation are alpha (`alpha`), beta (`beta`) and gamma (`gamma`) /X-rays. Health effects depend on energy and size.

Explanation:

Characteristics of alpha particles :

• contain 2 protons and 2 neutrons (nucleus of a helium atom)
• consisderable mass (in atomic terms)
• +2 charge

Because of the size of these particles, they have the least penetrating ability and can be stopped by a piece of paper or even by the top layer of your skin. This doesn't mean the particles have less energy, it only means they deposit their energy on a short distance. External `alpha`-radiation won't do much damage. When you ingest or inhale an `alpha`-particle it can do serious damage.

Characteristics of beta particles:

• the size of an electron
• small mass
• -1 charge

Because they are much smaller `beta`-particles have a better penetrating ability. However, because they do have a mass and a charge, they can be stopped by relatively ligh material. A few centimeters of perspex will usually stop the `beta`-particles completely. They deposit their energy over a larger area, but can still do considerable damge when ingested or inhaled. External radiation with `beta`-particle can damage sensitive tissues such as the eye (e.g. cataract).

Characteristics of gamma rays / X-rays:

• no mass, they are not particles but waves (fotons)
• no charge

Immediately you can see these are very different from the `alpha`- and `beta`-particles. In theory they can travel forever through material. For shielding of `gamma`-rays, lead is often used and/or thick layers of concrete. This reduces the transmission to an acceptable level. The fotons can easily penetrate the skin and it depends on their energy how much damage they do in the body.

Health effects are difficult to predict, genetic material (DNA) in your cells is the main target. In general there are three options:

• No damage to cells or damage that can be easily repaired
• Damage to DNA that causes the cell to stop functioning and/or causes it to die
• The damage in DNA is improperly repaired. The DNA-mutations can be inherited and it can lead to unlimited cell growth (cancer).