Which of the following is NOT a type of ionizing radiation?

Delta radiation is not recognized as a distinct type of ionizing radiation in the scientific community. Ionizing radiation is categorized into several well-defined types, primarily alpha, beta, and gamma radiation.

Alpha radiation consists of heavy particles that are emitted from unstable atomic nuclei. These particles are made up of two protons and two neutrons, similar to a helium nucleus. Due to their substantial mass and charge, alpha particles have low penetration power and can be stopped by a sheet of paper or even the outer layer of human skin.

Beta radiation is composed of high-energy, high-speed electrons (beta-minus) or positrons (beta-plus) emitted during certain types of radioactive decay. Beta particles can penetrate materials more deeply than alpha particles, requiring materials like plastic or glass to attenuate their effects.

Gamma radiation, on the other hand, consists of electromagnetic waves of very short wavelength and high energy. This type of radiation can penetrate most materials, including human tissue, and requires dense materials such as lead or several centimeters of concrete to reduce its intensity effectively.

Since delta radiation is not classified in the same way as these established types of ionizing radiation, it is correct to identify it as not being a type of ionizing radiation.