Which type of radiation produces the most ionisation?

Alpha radiation produces the most ionisation because it consists of heavy particles (helium nuclei) that carry a double positive charge. When alpha particles pass through matter, they have a strong interaction with the electrons in the atoms of the material due to their significant mass and charge. This interaction leads to a higher probability of ionisation, as alpha particles can effectively knock electrons out of atoms, creating ion pairs.

In contrast, beta radiation consists of lighter electrons or positrons, which, while still capable of causing ionisation, are less effective than alpha particles due to their lower mass and charge. Gamma radiation and X-ray radiation are forms of electromagnetic radiation, which are much more penetrating and interact less with matter, leading to less ionisation overall compared to alpha radiation. Thus, alpha radiation stands out as the most effective in producing ionisation among the types of radiation listed.