Alpha (α), beta (β), and gamma (γ) radiations are three common types of ionizing radiation emitted during radioactive decay.
They vary in their composition, charge, mass, penetrating power, and ionizing ability.
1. Alpha (α) radiation:
Composition: Alpha particles consist of two protons and two neutrons, resembling a helium-4 nucleus.
Charge: +2
Mass: Relatively high (~6,644 MeV/c²)
Penetrating Power: Low; can travel only a few centimeters in the air and are stopped by a sheet of paper or the outer layer of human skin.
Ionizing Power: High; due to their large mass and charge, they cause significant ionization in matter, leading to substantial energy transfer.
Alpha decay:
An unstable nucleus emits an alpha particle (two protons and two neutrons).
While alpha radiation poses little external hazard due to its low penetration, it is dangerous if ingested or inhaled, as it can damage internal tissues.
2. Beta (β) radiation:
Composition: Beta particles are either electrons (β⁻) or positrons (β⁺), the antiparticles of electrons.
Charge: -1 for electrons (β⁻), +1 for positrons (β⁺)
Mass: Relatively low (~0.511 MeV/c²)
Penetrating Power: Moderate; can travel a few meters in air and can be stopped by materials like plastic, glass, or aluminum.
Ionizing Power: Lower than alpha particles but higher than gamma rays; they can ionize atoms as they pass through matter.
Beta decay:
Involves the emission of a beta particle, which can be an electron (beta minus decay) or a positron (beta plus decay).
Beta particles have greater penetration than alpha particles but still require proper shielding, as they can penetrate the skin and damage living tissue.
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: None
Penetrating Power: High; can pass through most materials and human tissue, requiring dense materials like lead or thick concrete for shielding.
Ionizing Power: Lower than alpha and beta particles; although they ionize less efficiently, they can still cause ionization as they penetrate matter.
Gamma decay:
Occurs when a nucleus transitions from an excited state to a lower energy state, emitting gamma rays.
Gamma radiation poses a significant external hazard due to its high penetration, necessitating proper shielding and safety measures.