Which type of ionizing radiation has the greatest mass?

The type of ionizing radiation that possesses the greatest mass is alpha radiation. Alpha particles are composed of two protons and two neutrons, which means they have a significant mass compared to other forms of radiation. This structure gives alpha particles a much larger mass than beta particles, which are electrons or positrons with negligible mass, and gamma rays, which are a form of electromagnetic radiation and thus have no mass at all.

Neutrons, while they have mass and can be considered as a separate type of ionizing radiation, are typically not categorized in the same context as alpha and beta particles in this scenario due to the focus on charged particles. In most discussions on ionizing radiation types, alpha particles are recognized for their greater mass compared to beta particles and gamma rays. Thus, when comparing these forms of radiation, alpha particles stand out as the type with the greatest mass.