Francis William Aston

Born Sept. 1, 1877, in Har-borne; died Nov. 20, 1945, in Cambridge. English physicist. Member of the London Royal Society (1921). Corresponding member of the Academy of Sciences of the USSR (1924). Graduated from Birmingham and Cambridge universities. Taught at Birmingham University beginning in 1909. Member of Trinity College beginning in 1920.

In 1913, J. J. Thomson and Aston obtained the first indications of the existence of stable isotopes in neon. Aston constructed the first mass spectrometer and, with its aid, discovered 213 stable isotopes of chemical elements and determined their relative abundance. In 1925 he built a mass spectrograph with greater resolving power than the spectrometer; with it he made precise measurements of masses and determined the mass defects of a number of isotopes. In 1927, on the basis of the data he had obtained, he plotted the first curve of packing coefficients, which characterized the binding energy of atomic nuclei. He was awarded the Nobel Prize in 1922.