Emilio Segré (1905 - 1989)
Emilio Segré was born in Tivoli, Rome, on February 1, 1905. He enrolled at the University of Rome La Sapienza as an engeineering student, but switched to physics in 1927 and earned his doctorate in 1928, having studied under Enrico Fermi.
After a stint in the Italian Army in 1928 and 1929, Segre worked with Otto Stern in Hamburg and Pieter Zeeman in Amsterdam as a Rockefeller Foundation fellow in 1930. He was appointed assistant professor of physics at the University of Rome in 1932 and served until 1936. From 1936 to 1938, he was Director of the Physics Laboratory at the University of Palermo. After a visit to Ernest O. Lawrence's Berkeley Radiation Laboratory, he was sent a molybdenum strip from the lab's cyclotron deflector in 1937, which was emitting anomalous forms of radioactivity. After careful chemical and theoretical analysis, Segré was able to prove that some of the radiation was being produced by a previously unknown element, dubbed technetium, and was the first artificially synthesized chemical element that does not occur in nature.
While Segré was visiting California in 1938, Mussolini's Fascist government passed anti-Semitic laws barring Jews from university positions. As a Jew, Segré was now rendered an indefinite émigré. At the Berkeley Radiation Lab, Lawrence offered him a job as a research assistant. He also found work as a lecturer in the physics department at the University of California, Berkeley. While there, he, Kennedy, Seaborg and Wahl discovered the element astatine and the isotope plutonium-239, which was later used to make the atom bomb dropped on Nagasaki.
From 1943 to 1946, Segré worked at the Los Alamos National Laboratory as a group leader for the Manhattan Project. At Los Alamos, he was the leader of the Radioactivity Group. Their discovery of spontaneous fission of plutonium led to the reorganization of the Los Alamos Laboratory in the summer of 1944.
Also in 1944, Segré became a naturalized citizen of the U.S. Upon his return to Berkeley in 1946, he became a professor of physics, serving until 1972. In 1959, with Owen Chamberlain, he won the Nobel Prize in Physics for the discovery of the antiproton. In 1974, he returned to the University of Rome as a professor of nuclear physics.
An active photographer, Segré took many photos documenting events and people in the history of modern science. Segré died of a heart attack on April 22, 1989. The American Institute of Physics named its photographic archive of physics history in his honor.