Emilio Segrè

Born in Tivoli in 1905, Segrè switched from engineering to physics in 1927 and joined the Via Panisperna boys in Rome, where he became assistant professor by 1932. In 1937, examining a molybdenum strip from Berkeley's cyclotron, he proved the anomalous radiation came from technetium — the first element made by human hands. A year later, Mussolini's antisemitic laws caught him mid-visit to California; Lawrence offered him an underpaid research post, and he stayed. At Berkeley and then Los Alamos, he helped discover astatine and plutonium-239, and in April 1944 he found that the Thin Man weapon…