ALPHA, BETA AND GAMMA RAYS

Alpha, Beta and Gamma rays

Alpha, Beta and Gamma rays

Radioactivity

Atoms are not all stable. The excess energy contained in an unstable atom is released in one of a few basic particles and energetic waves. The Greek alphabet is used to name the particles (in the order of their discovery).

ALPHA PARTICLES

The alpha particle is the heaviest. It is produced when the heaviest elements decay. Alpha and beta rays are not waves. They are high-energy particles that are expelled from unstable nuclei. In the case of alpha radiation, the energy The particles leave the nucleus . The alpha particle is an helium atom and contains two neutrons and two protons. It leaves the nucleus of an unstable atom at a speed of 16,000 kilometres per second, around a tenth the speed of light. The alpha particles is relatively large and heavy. As a result, alpha rays are not very penetrating and are easily absorbed. A sheet of paper or a 3-cm layer of air is sufficient to stop them. Its energy is transferred within a short distance to the surrounding media. However, its short flight knocks about 450,000 electrons out of the surrounding atoms. The alpha particle emitter will not penetrate the outer layer of our skin, but is dangerous if inhaled or swallowed. The delicate internal workings of the living cell forming the lining of the lungs or internal organs, most certainly will be changed (mutated) or killed outright by the energetic alpha particle. The number of lung cancer cases among uranium miners from inhaled and ingested alpha sources is much higher than those of the public at large. Radon, the gas produced by the decay of radium-226, also emits alpha particles, which poses a hazard to lungs and airways when inhaled. Homes built in areas with high ground radioactivity should be tested for radon buildup in enclosed basement spaces.

BETA PARTICLES

Beta rays are much lighter energy particles. The beta particle is an energetic electron given off by the nucleus of unstable isotopes to restore an energy balance. They leave the nucleus at a speed of 270,000 kilometres per second. They can be stopped, for instance, by an aluminium sheet a few millimetres thick or by 3 metres of air. The RS-500 can detect most energetic beta particles through the case. Weaker beta particles can be detected through the tube window. Although the beta particle is around 8000 times smaller than the alpha particle, it is capable of penetrating much deeper into living matter. Each encounter with a living cell, and there may be many before the beta energy is dissipated, is likely to dam age some of the chemical links between the living molecules of the cell or cause some permanent genetic change in the cell nucleus. If the damage occurs within the generative cells of the ovaries or testes, the damage may be passed to new generations. The normal background radiation level must contribute to the mutation of the gene ...