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Thomson, Joseph John (1856–1940)

J. J. Thomson
English physicist who succeeded James Clerk Maxwell as professor of experimental physics (1883–1919) at Cambridge. J. J. Thomson's discovery of the electron is regarded as the birth of particle physics. Thomson established that cathode rays consisted of a stream of particles (see Crookes tube). He went on to prove that the electron was negatively charged and that its mass was about 2,000 times smaller than the smallest atom (hydrogen). He was awarded the 1906 Nobel Prize in Physics for his investigations into the electrical conductivity of gases.

Thomson and Francis Aston produced evidence of isotopes of neon. He transformed the Cavendish Laboratory into a major center for atomic research, attracting scientists of the caliber of Ernest Rutherford, who used Thomson's "currant-bun" model of the atom as a starting point for his own experimental investigations into the structure of the atom.

Thomson served as president (1915–20) of the Royal Society.

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