Radioactive particles

Radioactivity refers to the particles which are emitted from nuclei as a result of nuclear instability. Because the nucleus experiences the intense conflict between the two strongest forces in nature, it should not be surprising that there are many nuclear isotopes which are unstable and emit some kind of radiation. The most common types of radiation are called alpha, beta, and gamma radiation. Composed of two protons and two neutrons, the alpha particle is a nucleus of the element helium. Its range is less than a tenth of a millimeter but it has great destructive power within its short range.

In a cloud chamber, the path of a particle appears as a track of mist called a cloud track. By studying the track, or a photograph of it, a physicist can determine the energy and electric charge of the particle that produced it. Every kind of particle has a characteristic cloud track, which varies in shape, length, and width. Many elementary particles have been discovered through their characteristic cloud track.