The four basic types of ionizing radiation are:

The correct answer identifies the four fundamental types of ionizing radiation: neutron, beta, gamma, and alpha. Each of these types plays a significant role in the field of radiation safety and health physics, as they encompass the primary forms of radiation that can ionize atoms, which is the key factor in terms of potential biological effects.

Alpha radiation consists of heavy particles that are emitted from the nuclei of certain unstable isotopes. Due to their substantial mass and positive charge, alpha particles have low penetration power, being stopped by just a few centimeters of air or a sheet of paper, but they can cause significant damage to biological cells if ingested or inhaled.

Beta radiation involves electrons or positrons and is more penetrating than alpha particles but still can be blocked by materials such as plastic or glass. Beta particles can penetrate the outer layer of skin and potentially cause more harmful effects when they interact with living tissue.

Gamma radiation is a form of electromagnetic radiation of high energy and is very penetrating. It requires dense materials, like lead or several centimeters of concrete, for effective shielding. Gamma rays are often emitted alongside alpha or beta particles during radioactive decay processes and pose serious external exposure risks.

Neutrons are neutral particles that can easily pass through materials, including human tissue