Which type of radiation is most penetrating?

Gamma rays are the most penetrating type of radiation due to their nature as high-energy electromagnetic waves. Unlike alpha particles, which are heavy and positively charged, and beta particles, which are lighter and negatively charged, gamma rays are not composed of charged particles; instead, they are pure energy. This allows gamma rays to travel through matter with minimal interaction, allowing them to penetrate materials more effectively than other forms of radiation.

Gamma rays can pass through the human body and dense materials such as concrete or lead, but they do generally lose energy as they do so, albeit very slowly. This makes them difficult to shield against compared to alpha and beta radiation, which can be stopped by simple barriers (such as skin or a piece of paper for alpha, and plastic or aluminum for beta). Neutrons also have substantial penetrating ability, particularly when interacting with certain materials, but gamma rays still surpass them in terms of overall penetration capability due to their high energy and lack of charge.