Emilio Segre was a distinguished Italian-American physicist born on February 1, 1905, in Tivoli, Italy, who made seminal contributions to nuclear and particle physics throughout his illustrious career. Initially pursuing engineering at the University of Rome in 1922, he transitioned to physics under the mentorship of Enrico Fermi, earning his doctorate in 1928. His early career included serving as assistant professor at the University of Rome from 1932 and later as Director of the Physics Laboratory at the University of Palermo from 1936 to 1938, before emigrating to the United States in 1938 due to Mussolini's antisemitic policies. Following his naturalization as an American citizen in 1944, he joined the Manhattan Project and subsequently held professorships at the University of Chicago and the University of California, Berkeley, where he remained until 1972 before returning to the University of Rome as Professor of Nuclear Physics in 1974.
Segre's groundbreaking experimental work spanned atomic, nuclear, and particle physics, beginning with atomic spectroscopy until 1934 when he commenced pioneering neutron research with Fermi. He participated in the landmark discovery of slow neutrons in 1935, which proved crucial for nuclear reactor development, and co-discovered the first artificially synthesized element, technetium, in 1937 using materials from Berkeley's cyclotron. His collaborative discoveries extended to astatine with Corson and Mackenzie, and plutonium-239 with Kennedy, Seaborg, and Wahl, with his team's identification of plutonium's spontaneous fission properties proving critical to the Manhattan Project's bomb design. Most notably, in 1955, working with Chamberlain, Wiegand, and Ypsilantis at Berkeley's Radiation Laboratory, he achieved the first conclusive detection of the antiproton, confirming Paul Dirac's theoretical prediction and opening new frontiers in particle physics.
The profound impact of Segre's meticulous experimental approach extended across multiple scientific domains, with his discovery of slow neutrons fundamentally enabling nuclear fission research and the eventual development of nuclear energy. His work on radioactive isotopes and transuranic elements established foundational knowledge for modern nuclear chemistry and physics, while the antiproton discovery represented a watershed moment in subatomic particle research. Awarded the Nobel Prize in Physics in 1959 alongside Owen Chamberlain for identifying the antiproton, Segre's legacy endures through his transformative contributions to our understanding of matter's fundamental structure. His rigorous methodology and experimental precision continue to influence generations of physicists, cementing his status as one of the most significant experimental physicists of the twentieth century.
