There he met J.J. Thomson (who would soon discover the electron), and Thomson encouraged him to study recently-discovered ... of radiation: positively and negatively charged, or alpha and beta.

Film badges worn by medical personnel dealing with radiation are checked regularly. Inside the chamber, ionising radiations like Alpha and Beta will be indicated by tracks in the vapour.

high energy electromagnetic radiation emitted from unstable nuclei. It is normally emitted alongside alpha or beta radiation. Gamma ray emission causes no change in the number of particles in the ...