Alpha (α), beta (β), and gamma (γ) radiation are three common types of ionizing radiation emitted during radioactive decay.
They differ in their properties, such as mass, charge, and penetrating power, which affects their interactions with matter and their applications.
1. Alpha (α) radiation:
Composition: Alpha particles consist of two protons and two neutrons, essentially a helium-4 nucleus.
Charge: +2 (due to the two protons)
Mass: Relatively high (approximately 6,644 MeV/c^2)
Penetrating power: Low; alpha particles have a short range in air (a few centimeters) and can be stopped by a sheet of paper or the outer layer of human skin.
Ionizing power: High; due to their large mass and charge, alpha particles can cause significant ionization as they interact with matter, resulting in substantial energy transfer.
Alpha radiation is typically associated with heavy elements, such as uranium and plutonium, undergoing radioactive decay. While alpha radiation poses little external hazard due to its low penetrating power, it can be harmful if ingested or inhaled, causing damage to internal tissues and increasing the risk of cancer.
Alpha decay:
In this process, an unstable nucleus emits an alpha particle, which consists of two protons and two neutrons.
Alpha particles have relatively high mass and carry a positive charge.
Due to their large size and charge, alpha particles have limited penetrating power and can be stopped by a sheet of paper or the outer layer of human skin.
However, they can be harmful if ingested or inhaled, as they can damage cells and cause mutations.
2. Beta (β) radiation:
Composition: Beta particles are either electrons (β-) or positrons (β+), which are the antiparticle of electrons.
Charge: -1 for electrons (β-) and +1 for positrons (β+)
Mass: Relatively low (approximately 0.511 MeV/c^2 for both electrons and positrons)
Penetrating power: Moderate; beta particles have a longer range in air than alpha particles (up to a few meters) and can be stopped by a sheet of plastic, glass, or aluminum, depending on their energy.
Ionizing power: Lower than alpha particles but higher than gamma rays; beta particles can ionize atoms or molecules as they pass through matter, although not as efficiently as alpha particles.
Beta radiation is associated with various radioactive isotopes, such as carbon-14 and strontium-90, undergoing decay. Beta radiation can penetrate the skin and cause harm to living tissues, so proper shielding and handling are necessary to minimize exposure.
Beta decay:
This type of decay involves the emission of a beta particle, which can be either an electron (beta minus) or a positron (beta plus).
Beta particles have a smaller mass and carry either a negative (electron) or positive (positron) charge.
They have greater penetrating power than alpha particles but can be stopped by a sheet of plastic, glass, or aluminium.
3. Gamma (γ) radiation:
Composition: Gamma rays are high-energy electromagnetic radiation, similar to X-rays but with higher energy.
Charge: Neutral (no charge)
Mass: No mass
Penetrating power: High; gamma rays can pass through most materials, including human tissue, and can be stopped only by dense materials such as lead or thick layers of concrete.
Ionizing power: Lower than both alpha and beta particles; gamma rays can still ionize atoms and molecules, but they do so less efficiently as they pass through matter.
Gamma radiation is often emitted during nuclear transitions, such as the decay of a radioactive nucleus from an excited state to a lower energy state, or as a secondary product during alpha or beta decay. Due to their high penetrating power, gamma rays pose a significant external hazard and require appropriate shielding and safety measures.
Gamma decay:
This decay process is characterized by the emission of high-energy electromagnetic radiation called gamma rays.
Gamma rays have no mass or charge and are the most penetrating of the three types of radiation.
They can pass through most materials, including human tissue, and can be stopped only by dense materials such as lead or thick layers of concrete.