Demystifying Radiation: The Science, Detection, and Applications

We understand the intricacies of radiation - a natural phenomenon ubiquitously present in our daily lives.

Most individuals associate radiation with a negative connotation. However, radiation is a natural phenomenon and not always detrimental. In simple terms, radiation is the energy emitted by an object. When a material is radioactive, it releases energy as particles or electromagnetic waves. These particles could be electrons or atoms, and the waves could fall anywhere in the electromagnetic spectrum. Hence, even everyday objects such as light bulbs and Wi-Fi access points emulating electromagnetic waves technically qualify as radiation sources.

Understanding Ionizing Radiation

However, the term "radiation" commonly refers to a specific type known as ionizing radiation. Ionizing radiation is energy emitted by an object that can free an electron from its atom when interacting with other materials. A free electron can then interact with other particles or drift into space. The phenomenon where the electron separates from its original fraction is known as ionization.

Ionizing radiation was discovered serendipitously in 1896 by French physicist Henri Becquerel. He found that uranium salts affected unexposed photographic film, similar to light, but unlike light, it could penetrate the paper wrapping. This was an ionizing radiation emitted by uranium - a naturally radioactive substance.

Applications of Ionizing Radiation

Ionizing radiation finds use in several everyday applications. For instance, smoke detectors use a radioactive source to ionize the air inside the sensor. The presence of smoke disrupts this ionization, triggering an alarm. Similarly, nuclear power plants supply 18% of the US's electrical power and produce ionizing radiation. Medical X-ray imaging, certain ceramic dishes, and even bananas (due to their high potassium content) are sources of ionizing radiation. Cosmic rays from outer space are another example.

The Perils of Ionizing Radiation

While ionizing radiation has its uses, it can also be harmful. Free electrons can interact with molecules in human body cells and tissues, potentially breaking chemical bonds and increasing cancer risk. This is the danger associated with radioactive substances in nuclear weapons and power plant meltdowns.

Types of Ionizing Radiation

Ionizing radiation can be classified into four types: alpha particles, beta particles, gamma rays, and neutron radiation. Each type interacts differently with matter and can be detected using different methods.

Alpha Particles

Unlike "alpha rays," alpha particles are not waves but electrically charged particles. They are composed of two protons and two neutrons, making them helium atoms without electrons. A sheet of paper can easily block Alpha particles, making them the least harmful of the radiation types.

Beta Particles

Beta particles are electrons. They are much lighter than alpha particles and can be emitted at high speeds, enabling them to penetrate objects, including the human body.

Gamma Rays

Gamma rays are a type of electromagnetic wave similar to visible light but with a much smaller wavelength. Their small wavelength and high frequency allow them to interact with matter at high energy levels and penetrate deep into most materials.

Neutron Radiation

Unlike alpha, beta, and gamma radiations, neutron radiation involves the ejection of a neutron from a radioactive nucleus. These neutrons can split an atom into two new atoms or be absorbed into the heart, creating an unstable isotope. This unstable nucleus undergoes radioactive decay, producing beta and gamma rays.

Radiation Detection

Different methods for detecting radiation include the Geiger counter and a scintillator. The Geiger counter utilizes a gas-filled tube to identify ionization caused by alpha, beta, or gamma rays. Meanwhile, a scintillator is a specially created material that releases a small amount of visible light when exposed to any of the four types of radiation. This light is then detected using a photomultiplier tube. Even smartphones can see gamma rays and x-rays due to their image sensors.