4.2.1 Radioactive Decay and Nuclear Radiation

In this lesson, we will explore the concept of radioactive decay, the measurement of activity, different types of nuclear radiation, and their properties. We will also discuss the uses of radiation and how to evaluate the best sources of radiation for specific situations.

Radioactive Decay

Some atomic nuclei are unstable and undergo spontaneous changes in order to become more stable.

Radioactive decay is the process by which an unstable nucleusA membrane-bound organelle in eukaryotic cells that contains DNA. emits radiation as it undergoes a transformation to a more stable state. It is a random process that occurs at the atomic level.

Activity and Measurement

Activity is the rate at which a source of unstable nuclei decays. It is measured in becquerels (Bq), which represents the number of radioactive decays per second.

The count-rate is the number of decays recorded per second by a detector, such as a Geiger-Muller tube.

Types of Nuclear Radiation

• Alpha Particles (α): Alpha particles consist of two neutrons and two protons, making them identical to a helium nucleus.
• Beta Particles (β): Beta particles are high-speed electrons that are ejected from the nucleus when a neutron transforms into a proton.
• Gamma Rays (γ): Gamma rays are electromagnetic radiation emitted from the nucleus.
• Neutrons (n): Neutrons are electrically neutral particles emitted by some radioactive nuclei.

Properties of Nuclear Radiation

• Penetration: Alpha particles have low penetration power and can be stopped by a few centimetres of air or a sheet of paper. Beta particles can penetrate further, while gamma rays have the highest penetration power and require thick shielding.
• Range in Air: Alpha particles have a short range in air, beta particles can travel further, and gamma rays have an unlimited range.
• Ionising Power: Alpha particles have high ionising power due to their large mass and charge. Beta particles have lower ionising power, and gamma rays have the least ionising power.

Uses of Radiation

• Medical Applications: Radiation is used in medical imaging, cancer treatment (radiotherapy), and sterilisationProcess through which any trace of life is removed. Essential in preparing fermentation vessels to avoid contamination. of medical equipment.
• Industrial Applications: Radiation is used in industrial processes such as quality control, material testing, and radiography.
• Energy Generation: Nuclear power plants use controlled nuclear reactions to generate electricity.

Evaluating Radiation Sources

When evaluating the best sources of radiation for a given situation, factors to consider include the specific properties of the radiation needed, safety measures, cost-effectiveness, and suitability for the intended application.

Conclusion

Radioactive decay is a natural process where unstable atomic nuclei undergo transformations to achieve stability, emitting various types of nuclear radiation in the form of alpha particles, beta particles, gamma rays, and neutrons. The activity of a radioactive source is measured in becquerels (Bq), representing the rate of decay per second. Each type of radiation possesses unique properties, including penetration power, range in air, and ionising power, which determine their uses in various fields such as medical imaging, cancer treatment, industrial processes, and energy generation. When choosing radiation sources, careful consideration of specific properties, safety measures, cost-effectiveness, and suitability for the intended application is essential.